JP2006301597A - Laser apparatus and method for assembling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure output and service life of a semiconductor laser at a high level and to fix, with high positional accuracy, optical components comprising an optical condensing system, in a laser apparatus in which a laser beam emitted from the semiconductor laser arranged inside the package is converged by the optical condensing system and made to couple with an optical fiber. <P>SOLUTION: The laser apparatus includes: a semiconductor laser LD7; an optical fiber 30; an optical condensing system (e.g., composed of a collimator lens array 18 and a condensing lens 20) which condenses a laser beam B7 emitted from the semiconductor laser LD7 to make an incident end of the optical fiber 30 irradiated with the laser beam; and a package 40. In this apparatus, the elements 18, 20 comprising the optical condensing system are fixed, with a thin layer of adhesive, to fixing members 10, 45 fixed to the package 40, while the semiconductor laser LD7 is fixed to the fixing member 10 with solder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser device, and more particularly to a laser device in which a laser beam emitted from a semiconductor laser housed in a package is coupled to an optical fiber.

  The present invention also relates to a method for assembling the laser device as described above.

  Conventionally, as shown in Patent Documents 1 and 2, for example, there is known a laser apparatus that obtains a high-power laser beam by inputting a plurality of laser beams into a single optical fiber and combining them. Yes. This laser apparatus basically includes one or more semiconductor lasers that emit a plurality of laser beams, one optical fiber, and a plurality of laser beams emitted from the semiconductor laser, and then the incidence of the optical fiber. It is comprised from the condensing optical system irradiated to an edge.

  For example, as disclosed in Patent Document 3, a laser beam emitted from one semiconductor laser is condensed by a condensing optical system without particularly combining a plurality of laser beams into one. Laser devices that are coupled to optical fibers are also known.

The semiconductor laser and the condensing optical system are often hermetically sealed in a package in order to prevent contamination due to dust, dust, and the like. In such a case, optical components such as a semiconductor laser and a condensing lens constituting a condensing optical system are generally fixed to a fixing member or a holder fixed on the package side using an adhesive or solder. It is. In addition, when such a package is used, the optical fiber is fixed to the package with its incident end facing the condensing optical system, and the above-mentioned adhesive and solder are also used for the fixing. There are many. Patent Document 2 shows an example of a structure for fixing an optical fiber to a package using an adhesive.
JP 2003-347647 A JP 2004-045667 A Japanese Patent Laid-Open No. 07-013047

  By the way, when a semiconductor laser or an optical component is fixed to the package as described above or a fixing member fixed to the package, if a solder or an adhesive is used for the fixing, the output or life of the semiconductor laser is reduced, or the optical fiber and the optical component are reduced. There is a problem that the positional accuracy of a condenser lens or the like that needs to be aligned with accuracy cannot be ensured to an originally required error of about 1 μm, and the error increases to about several μm.

  SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a laser device that can secure a high output and long life of a semiconductor laser, and can fix an optical component constituting a condensing optical system with high positional accuracy, and an assembling method thereof. The purpose is to do.

The laser device according to the present invention uses a solder or an adhesive for fixing a semiconductor laser or an optical component, but solves the problem by properly using them depending on the object to be fixed. As mentioned above,
A semiconductor laser,
With optical fiber,
A condensing optical system that condenses the laser beam emitted from the semiconductor laser and irradiates the incident end of the optical fiber;
In the laser apparatus comprising the condensing optical system and the semiconductor laser fixedly housed therein, and the optical fiber having a package in which the incident end is fixed to face the condensing optical system,
The optical component constituting the condensing optical system is fixed to the package or a fixing member fixed thereto by a thin layer adhesive (defined as an adhesive having a thickness of 2 μm or less after drying), The semiconductor laser is fixed by solder.

  The fixing member to which the semiconductor laser is fixed and the fixing member to which the optical component is fixed are preferably fixed to the package by soldering.

  In the laser apparatus of the present invention, it is preferable that a holder is fixed to the fixing member by a thin layer adhesive, and an optical component constituting the condensing optical system is fixed to the holder by the thin layer adhesive.

  In the laser apparatus of the present invention, not only the semiconductor laser but also a plurality of elements including the semiconductor laser may be fixed to the package or a fixing member fixed thereto by soldering. As the solder to be fixed, the same solder may be used, or solders having different melting points may be used.

  On the other hand, the laser device assembly method according to the present invention is a method of assembling the laser device according to the present invention as described above, and after fixing the element fixed by solder, the element fixed by the thin layer adhesive is fixed. It is characterized by doing.

  In the laser device assembling method according to the present invention, when a plurality of types of solders having different melting points are used, the fixing point using the first solder having a higher melting point is terminated and the melting point is lower. The fixing operation using the second solder is desirably performed by melting the second solder at a temperature lower than the melting point of the first solder.

  According to the research of the present inventor, it has been found that in the conventional laser device, the problem that the output and life of the semiconductor laser are reduced occurs when the semiconductor laser is fixed to the package side with an adhesive. That is, an organic adhesive such as an ultraviolet curable adhesive is generally used as this type of adhesive, but such an adhesive has a lower thermal conductivity than solder, and therefore, the semiconductor laser is exposed to the package side. As a result, the heat dissipation is impaired, and the semiconductor laser is driven at a high temperature, leading to a reduction in output and life.

  In many cases, the semiconductor laser is not directly fixed to the package, but is fixed to a fixing member made of copper or the like with high thermal conductivity fixed to the package. If an adhesive is used for fixing the laser, heat dissipation from the semiconductor laser to the fixing member is impaired in the adhesive layer.

  Based on the above knowledge, in the laser device of the present invention, the semiconductor laser is fixed to the package or the fixing member fixed thereto by solder, so that the heat generated by the semiconductor laser is higher than that of the adhesive. Heat is radiated to the package or the fixing member through the highly conductive solder. If so, the semiconductor laser is not driven at a high temperature due to poor heat dissipation, and its output and life are prevented from being reduced.

  On the other hand, according to the research of the present inventors, in the conventional laser apparatus, the problem that the positional accuracy of the optical components constituting the condensing optical system is lowered occurs when they are fixed to the package or the fixing member by solder. Turned out to be. That is, the fixing of the optical component by the solder is performed by placing the solder between the solder and the package or the fixing member, heating and melting the solder, and then solidifying the solder. The parts move slightly.

  Based on the above knowledge, in the laser device of the present invention, since the optical components constituting the condensing optical system are fixed to the package or the fixing member fixed thereto by the thin layer adhesive, the melting of the solder Therefore, the optical component does not move, and the positional accuracy is kept high.

  When the fixing member to which the semiconductor laser is fixed is fixed to the package with solder, the heat radiation from the fixing member to the package is also improved, so that the output and life of the semiconductor laser are prevented from being reduced. The effect becomes more remarkable.

  In addition, when the fixing member to which the optical component constituting the condensing optical system is fixed is fixed to the package by solder, the positional accuracy of the fixing member with respect to the package tends to be lower than that when an adhesive is used. It can be said that there is. However, even if the positional accuracy of the fixing member is low, when the optical component is fixed to the fixing member with an adhesive, it is only necessary to accurately align the optical component with the optical fiber. Low is not a problem.

  In the laser apparatus of the present invention, when the holder is fixed to the fixing member, and the optical component constituting the condensing optical system is fixed to the holder, the holder is moved along the fixing member for positioning, and the optical device Since the component can be moved and positioned following the holder, the optical component can be positioned easily. In that case, if both the fixing of the holder and the fixing of the optical component are performed by the thin layer adhesive, the positioning accuracy of the optical component becomes high.

  On the other hand, in the laser apparatus of the present invention, when a plurality of elements including a semiconductor laser are fixed to the package side with solder, if the same solder is used as each of the elements for fixing the elements, the procurement and management of the solder Is facilitated, and the cost of the laser device can be reduced.

  However, in this case, since the melting point of the solder used is naturally the same for all the solders, when the package is heated as a whole when the solder is melted, the solder fixing the existing elements melts, There is a risk of the element moving or peeling off. Therefore, in such a case, it is necessary to melt the solder locally for each fixed portion so that heat is not transmitted to the portion already fixed by the solder.

  On the other hand, when solders each having a different melting point are used as the solder for fixing each of the plurality of elements including the semiconductor laser, the heating operation can be simplified by applying the method of the present invention described later. it can.

  On the other hand, the assembly method of the laser device according to the present invention fixes the element fixed by the thin layer adhesive after fixing the element fixed by the solder, so that the positional accuracy of the element fixed by the solder is high. Even if it is lowered, if the fixing position accuracy is kept high when the optical component or the like is subsequently fixed by the thin layer adhesive, the positioning accuracy of the optical component or the like with respect to the optical fiber can be finally secured high.

  In the method of assembling a laser apparatus according to the present invention, as described above, the fixing operation using the first solder having a higher melting point is completed particularly when solders each having a different melting point are used as the solder for fixing each of the plurality of elements. Then, if the fixing operation using the second solder having a lower melting point is performed by melting the second solder at a temperature lower than the melting point of the first solder, the fixing operation using the second solder is performed. Even if the heat at this time is transferred to the portion already fixed by the first solder, the first solder will not be melted. Therefore, in this case, the package may be heated as a whole when the solder is melted, and the heating operation becomes easier.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1, 2, and 3 respectively show a planar shape, a side shape, and a partial front shape of an ultraviolet high-intensity combined laser device that is an embodiment of the present invention. As shown in the figure, this combined laser light source is arranged as an array and fixed on a heat block 10 having high thermal conductivity. As an example, seven chip-shaped lateral multimode GaN semiconductor lasers LD1, LD2, LD3, LD4, LD5, and LD6 are used. And LD7 and collimating lenses 11, 12, 13, 14, 15, 16, and 17 corresponding to the GaN semiconductor lasers LD1, LD2, LD3, LD4, LD5, LD6, and LD7, respectively, are integrally formed. The lens array 18, one condenser lens 20, and one multimode optical fiber 30 are provided.

  The GaN-based semiconductor lasers LD1 to LD7 have a common oscillation wavelength of, for example, 405 ± 5 nm, and the maximum output is also a common 50 to 300 mW. In this embodiment, single-mode GaN semiconductor lasers LD1 to LD7 are used, but multimode semiconductor lasers can also be applied.

  Laser beams B1, B2, B3, B4, B5, B6, and B7 emitted from these GaN-based semiconductor lasers LD1, LD2, LD3, LD4, LD5, LD6, and LD7 in a divergent light state are collimated in the collimating lens array 18, respectively. The lenses 11, 12, 13, 14, 15, 16, and 17 are collimated. FIG. 3 shows a state in which the collimating lens array 18 side is viewed from the position AA in FIG.

  The parallel laser beams B1 to B7 are condensed by the condenser lens 20 and converge on the incident end face of the core 30a of the multimode optical fiber 30. In this example, the collimating lenses 11 to 17 and the condensing lens 20 constitute a condensing optical system, and the multimode optical fiber 30 constitutes a multiplexing optical system. That is, the laser beams B1 to B7 condensed as described above by the condenser lens 20 enter the core 30a of the multimode optical fiber 30, propagate there, and are combined into one laser beam B to be multimode. The light is emitted from the optical fiber 30. As the multimode optical fiber 30, a step index type, a graded index type, and a composite type thereof can be applied.

  In this embodiment, the optical element constituting the multiplexing laser device is accommodated in a box-shaped package 40 having an upper opening, and the opening of the package 40 is closed by a package lid 41, whereby the package 40 and the package are packaged. The lid 41 is hermetically held in a closed space that defines the lid 41. Further, the end portion on the incident side of the multimode optical fiber 30 is held by the ferrule 31 and is fixed to the side wall portion of the package 40.

  A base plate 42 is fixed to the bottom surface of the package 40, the heat block 10 is attached to the upper surface of the base plate 42, and the GaN-based semiconductor lasers LD1 to LD7 are fixed to the upper surface 10a of the heat block 10, A collimating lens holder 44 that holds the collimating lens array 18 is fixed to the front surface 10b. Further, a lens fixing base 45 is fixed to the upper surface of the base plate 42, and a condensing lens holder 46 for holding the condensing lens 20 is fixed to a front surface 45a of the lens fixing base 45. In addition, wirings 47 for supplying a driving current to the GaN-based semiconductor lasers LD1 to LD7 are drawn out of the package through openings formed in the side walls of the package 40.

  As shown in FIG. 3, each of the collimating lenses 11 to 17 of the collimating lens array 18 is formed by cutting a region including the optical axis of the aspherical circular lens into an elongated shape. For example, it is formed by molding optical glass. The collimating lenses 11 to 17 have aperture diameters in the direction in which the light emitting points of the GaN-based semiconductor lasers LD1 to LD7 are arranged (left and right in FIG. 3) perpendicular to the direction (up and down in FIG. 3). It is formed small and closely arranged in the direction in which the light emitting points are arranged.

  On the other hand, the GaN-based semiconductor lasers LD1 to LD7 emit laser beams B1 to B7 having an emission width of 2 μm and divergence angles in a direction parallel to and perpendicular to the active layer, for example, 10 ° and 30 °, respectively. Things are used. These GaN-based semiconductor lasers LD1 to LD7 are arranged so that the light emitting points are arranged in a line in a direction parallel to the active layer.

  Therefore, the laser beams B1 to B7 emitted from the respective light emitting points correspond to the direction in which the divergence angle is maximum with respect to the elongated collimating lenses 11 to 17 as described above, and the direction in which the aperture diameter is large, Incident light enters in a state where the direction with the smallest divergence angle coincides with the direction with a small aperture diameter. That is, the elongated collimating lenses 11 to 17 are used with as few ineffective portions as possible corresponding to the elliptical cross-sectional shape of the incident laser beams B1 to B7. Specifically, in the present embodiment, the effective aperture diameters of the collimating lenses 11 to 17 are 1.1 mm and 3.6 mm in the horizontal direction and the vertical direction, respectively, and the horizontal and vertical beams of the laser beams B1 to 7 incident thereon. The diameters are 0.9 mm and 2.6 mm, respectively. The focal lengths f1 of the collimating lenses 11 to 17 are 3 mm, NA (numerical aperture) is 0.6, and the lens arrangement pitch is 1.2 mm.

  On the other hand, the condensing lens 20 is formed by cutting a region including the optical axis of the aspherical circular lens into a long and narrow shape that is long in the alignment direction of the collimating lenses 11 to 17, that is, in the horizontal direction, and short in the direction perpendicular thereto. The focal length f2 of the condenser lens 20 is 23.15 mm and the magnification is 7.7. The condensing lens 20 is also formed by molding optical glass, for example. The condensing lens 20 and the collimating lens array 18 can be made of synthetic resin in addition to glass.

  As the multimode optical fiber 30, a step index type optical fiber having a core diameter = 60 μm, NA = 0.23, end coat transmittance = 99.5%, and internal loss = 98.5% is used.

  In the configuration of the present embodiment, the coupling efficiency of the laser beams B1 to B7 to the multimode optical fiber 30 is 0.9. Therefore, when the outputs of the GaN-based semiconductor lasers LD1 to LD7 are 50 to 300 mW, a combined laser beam B having an output of 0.315 to 1.89 W (= 50 to 300 mW × 0.9 × 7) is obtained.

  Hereinafter, the fixing structure of the elements constituting the multiplexing laser device will be described in detail. Each element described below is fixed using either solder or an organic adhesive. In FIG. 2, the former adhesion portion is marked with a black circle, and the latter adhesion portion is a white circle. Is attached. In addition, all the fixing with the organic adhesive is performed in such a manner that an adhesive is spotted between the two surfaces in a state where the two surfaces to be bonded are in close contact as will be described later. If it does so, the adhesive after drying will become a film thickness of 2 micrometers or less, and will be thinned.

  First, the GaN-based semiconductor lasers LD1 to LD7 are fixed as follows. The GaN semiconductor lasers LD1 to LD7 are mounted on the upper surface 10a of the heat block 10 using Sn—Au solder having a melting point of 280 ° C. The heat block 10 is formed in a rectangular parallelepiped shape from AlN (aluminum nitride) excellent in thermal conductivity and polishing processability. In this mounting, first, the GaN-based semiconductor lasers LD1 to LD7 are temporarily fixed to the upper surface 10a of the heat block 10 one by one with Sn—Au solder set at a first temperature lower than the melting point. After all the GaN-based semiconductor lasers LD1 to LD7 are temporarily fixed, the Sn-Au solder is melted by raising the temperature to a second temperature exceeding the melting point in a reflow furnace, and the GaN-based semiconductor lasers LD1 to LD7 are fixed. The As an example, the first temperature and the second temperature are set to 150 ° C. and 330 ° C., respectively.

  By doing so, the Sn-Au solder in the unmounted portion does not exceed the melting point until all the chip-like GaN-based semiconductor lasers LD1 to 7 are completely mounted, so that the solder is prevented from being oxidized. Mounting with stable high accuracy (for example, a dimensional error of about ± 0.1 μm) is possible.

  The chip-like GaN-based semiconductor lasers LD1 to LD7 may be directly fixed to the heat block 10 as they are, or each semiconductor laser is fixed to an individual submount using solder, and the submount is It may be fixed to the heat block 10 as described above.

On the other hand, the ferrule 31 holding the multimode optical fiber 30 on the incident side is fixed to the side wall of the package 40 using, for example, Sn-3.5Ag-0.5Cu solder having a melting point of 220.degree. . This fixing is performed by using a C-type ring solder made of Sn-3.5Ag-0.5Cu (2 annular solders) between the inner periphery of the ferrule insertion circular hole formed in the side wall portion of the package 40 and the outer periphery of the ferrule 31. And the C-shaped ring solder is melt-sealed by local heating. At this time, the multi-mode optical fiber 30 is fixed in a state where the core axis thereof is perpendicular to the front surface 10b of the heat block 10 with high accuracy. In order to prevent oxidation of the C-type ring solder due to heating, a low oxygen atmosphere may be created by blowing N ₂ assist gas and heated.

  Next, the heat block 10 on which the GaN-based semiconductor lasers LD 1 to 7 are mounted is fixed on the base plate 42. The lower surface of the heat block 10 is metallized by gold vapor deposition, and the lower surface is fixed on the Au-plated base plate 42 using, for example, Sn48-In52 solder having a melting point of 117 ° C. The base plate 42 is formed of, for example, CuW, CuMo, Kovar, or the like, and is fixed to the bottom surface of the package 40.

  The rectangular parallelepiped heat block 10 is fixed so that the front surface 10b of the cuboid heat block 10 is perpendicular to the base plate 42 with high accuracy. The front surface 10b is mirror-finished to serve as a mounting surface to which the collimating lens holder 44 is fixed and a reference surface to be described later.

  As described above, when the heat block 10 is fixed on the base plate 42, the Sn48-In52 solder has a melting point of slightly higher than 117 ° C, Sn-Au solder melting point 280 ° C, and Sn-3.5Ag-0.5Cu solder. It is melted by heating to a temperature lower than 220 ° C., for example, 150 ° C. By doing so, the Sn—Au solder that fixes the GaN-based semiconductor lasers LD1 to LD7 is not melted, or the Sn-3.5Ag-0.5Cu solder that fixes the ferrule 31 is not melted. The fixation of the GaN-based semiconductor lasers LD1 to LD7 and the ferrule 31 is reliably maintained.

  Next, the fixing structure of the collimating lens array 18 and the collimating lens holder 44 will be described. In this combined laser apparatus, the collimating lens array 18 and the condensing lens 20 have the optical axis as the core axis of the multimode optical fiber 30 in order to ensure high coupling efficiency of the laser beams B1 to B7 to the multimode optical fiber 30. (The core axis at the entrance end; the same shall apply hereinafter) and must be fixed in parallel with each other. This will be described below.

  Prior to the adhesion and fixing of the collimating lens holder 44, a mounting surface and a reference surface of the heat block 10 using a laser autocollimator 50 and a mirror 51 placed on the base plate 42 as shown in FIG. The angle of the front surface 10b with respect to the reference direction is measured. In the present embodiment, the laser beam Br emitted from the laser autocollimator 50 is reflected by the mirror 51 so that the traveling direction is changed by 90 ° and is incident perpendicularly on the front surface 10b of the heat block. The traveling direction z of the laser beam Br is the reference direction.

  The laser autocollimator 50 receives the laser beam Br reflected by the heat block front surface 10b and re-reflected by the mirror 51, and measures the angle of the heat block front surface 10b with respect to the reference direction z. This angle is defined by inclination angles θx and θy about the x-axis and y-axis that are perpendicular to the reference direction z and perpendicular to each other. That is, for example, when the heat block front surface 10b is completely perpendicular to the reference direction z, the inclination angle θx = θy = 0 °. The y-axis direction is the same as the traveling direction of the laser beam Br emitted from the laser autocollimator 50 and traveling downward. The measured inclination angles θx and θy are recorded on a recording sheet or the like, or stored in a storage unit.

  Next, as shown in FIG. 5, for example, using a mechanical hand 52 having a gripping portion 52a for gripping the collimating lens holder 44, the rear surface 44a, which is an adhesive surface, is in a state of lightly contacting the heat block front surface 10b. 44 is retained. As the mechanical hand 52, for example, a six-axis one that can move the gripping portion 52a in parallel in the three-axis direction and rotate around the three axes is used. The force for bringing the collimating lens holder rear surface 44a into contact with the heat block front surface 10b can be maintained at a predetermined value by using a load cell or the like incorporated in the mechanical hand 52, for example.

  Further, when holding the collimating lens holder 44 as described above, the angle of the front surface 44b as a reference surface with respect to the reference direction z is continuously measured. This angle measurement is performed in the same manner as the angle measurement of the heat block front surface 10b, and the measurement angle is similarly defined by the aforementioned inclination angles θx and θy.

  At this time, in the mechanical hand 52, the continuously measured inclination angles θx and θy coincide with the inclination angles θx and θy measured for the heat block front surface 10b, respectively, and the collimating lens holder 44 is moved to x, y. The mechanical hand 52 is stopped when it is operated so as to be arranged at a predetermined position in the direction and the state is reached. Next, an adhesive is spotted between the front surface 10b of the heat block and the rear surface 44a of the collimating lens holder 44 that is lightly in contact therewith, and by curing it, the collimating lens holder 44 adheres to the heat block front surface 10b. Fixed.

  In order to place the collimating lens holder 44 at a predetermined position in the x and y directions as described above, the rear surface 44a may be slid on the heat block front surface 10a, so that the operation is facilitated. obtain.

  Here, the collimating lens holder 44 is formed such that the rear surface 44a and the front surface 44b are parallel to each other with high accuracy (error ± 15 ″). If so, the collimating lens holder 44 is formed as described above. That the inclination angles θx and θy measured for the front surface 44b of each of the front and rear surfaces 44b coincide with the inclination angles θx and θy measured for the heat block front surface 10b, respectively. Therefore, if the collimating lens holder 44 is adhered and fixed to the heat block front surface 10b while maintaining this state, the collimating lens holder is in a state where the rear surface 44a is parallel to the heat block front surface 10b with high accuracy. 44 is fixed.

  At this time, the operation of the mechanical hand 52 is controlled based on the external dimensions of the collimating lens holder 44 that have been precisely measured in advance, and the angular position around the z-axis of the collimating lens holder 44 is set to a predetermined position. Thus, the collimating lens holder 44 is fixed in a state where its upper surface 44c is parallel to the base plate 42 with high accuracy.

  The parallelism between the rear surface 44a and the front surface 44b of the collimating lens holder 44 whose numerical values are given above can be easily realized by polishing the surfaces.

  In addition, as an example of the adhesive, an ultraviolet curable organic adhesive is used. As described above, the collimating lens holder 44 is formed of an ultraviolet transmissive glass. And the adhesive is sufficiently irradiated.

  Thereafter, the mechanical hand 52 is operated so as to retract the grip portion 52 a out of the package 40. Next, as shown in FIG. 6, the angle with respect to the reference direction of the upper surface 44c of the fixed collimating lens holder 44 is measured using the laser autocollimator 50 again. The reference direction in this case is the traveling direction of the laser beam Br emitted from the laser autocollimator 50 and traveling downward (this is the same as in FIGS. 4 and 5). That is, here, the angle of the collimating lens holder upper surface 44c with respect to the reference direction y is defined by the inclination angles φx and φz around the x-axis and the z-axis. That is, for example, when the collimating lens holder upper surface 44c is completely perpendicular to the reference direction y, the inclination angle φx = φz = 0 °. The measured inclination angles φx and φz are recorded on a recording sheet or the like or stored in a storage unit.

  Next, as shown in FIG. 7, the collimating lens array 18 is held again using the mechanical hand 52 so that the lower surface (adhesion surface) 18 a of the collimating lens holder 44 is in light contact with the upper surface 44 c of the collimating lens holder 44. When the collimating lens array 18 is held in this way, the angle of the upper surface 18b with respect to the reference direction y is continuously measured. This angle measurement is performed in the same manner as the angle measurement of the collimating lens holder upper surface 44c, and the measurement angle is similarly defined by the aforementioned inclination angles φx and φz.

  At this time, in the mechanical hand 52, the continuously measured tilt angles φx and φz coincide with the tilt angles φx and φz measured on the collimating lens holder upper surface 44c, respectively, and the collimating lens array 18 is moved in the x and z directions. The mechanical hand 52 is stopped when it is operated so as to be disposed at a predetermined position and when the state is reached. Next, an adhesive is spotted between the collimating lens holder upper surface 44c and the lower surface 18a of the collimating lens array 18 that is lightly in contact with the collimating lens holder, and the collimating lens array 18 is cured by curing it. Adhered and fixed to.

  In order to place the collimating lens array 18 at a predetermined position in the x and z directions as described above, the lower surface 18a may be slid on the upper surface 44c of the collimating lens holder, so that the operation is facilitated. obtain.

  Here, the collimating lens array 18 is formed such that its lower surface 18a and upper surface 18b are parallel to each other with high accuracy. If so, the tilt angles φx and φz measured for the upper surface 18b of the collimating lens array 18 as described above are respectively coincident with the tilt angles φx and φz measured for the collimating lens holder upper surface 44c. Means that the lower surface 18a is parallel to the upper surface 44c of the collimating lens holder. Therefore, if the collimating lens array 18 is bonded and fixed to the upper surface 44c of the collimating lens holder while maintaining this state, the collimating lens array 18 is fixed with the lower surface 18a parallel to the upper surface 44c of the collimating lens holder with high accuracy.

  At this time, for example, the operation of the mechanical hand 52 is controlled based on the outer dimensions of the collimating lens array 18, and the angular position around the y-axis of the collimating lens array 18 is set to a predetermined position. The array 18 is fixed in a state where the optical axes of the collimating lenses 11 to 17 are parallel to the core axis of the multimode optical fiber 30.

  Even if the angular position around the y axis of the collimating lens array 18 and the angular position around the z axis of the collimating lens holder 44 are set to predetermined positions by controlling the operation of the mechanical hand 52 as described above, It is difficult to perform surface matching of each member with high accuracy, and in view of this point, in this embodiment, surface matching using a reference surface is employed.

  Note that the parallelism between the lower surface 18a and the upper surface 18b can be made highly accurate with an error of about ± 15 ″ by molding the collimating lens array 18 with high accuracy. Accordingly, the angle with the upper surface 18b as the reference surface. By measurement, the lower surface 18a can be aligned parallel to the collimating lens holder upper surface 44c with a maximum error of 30 ″. Note that the parallelism of the lower surface 18a and the upper surface 18b of the collimating lens array 18 with respect to the lens arrangement direction can be made as high as an accuracy of about ± 15 ″.

  In addition, as an example of the adhesive, an ultraviolet curable organic adhesive is used. As described above, the collimating lens holder 44 is formed of ultraviolet transmissive glass, and the collimating lens array 18 is the same. The ultraviolet rays pass through the collimating lens holder 44 and the collimating lens array 18 so that the adhesive is sufficiently irradiated.

  As described above, when the collimating lens holder 44 is bonded and fixed to the heat block 10 and the collimating lens array 18 is bonded and fixed to the collimating lens holder 44, the collimating lens array 18 has multiple optical axes of the collimating lenses 11 to 17. The mode optical fiber 30 is fixed in a state of being parallel to the core axis with high accuracy.

  In the structure described above, the heat block 10 and the collimating lens holder 44 correspond to the fixing member in the present invention.

  Next, returning to FIG. 2, the fixing structure of the condenser lens 20 and the condenser lens holder 46 will be described. The lens fixing base 45 for fixing the condenser lens holder 46 is formed in a rectangular parallelepiped shape using AlN similarly to the heat block 10, the lower surface is metallized by gold vapor deposition, and the lower surface is a base plate 42 with Au plating. For example, it is fixed using Sn48-In52 solder having a melting point of 117 ° C. At this time, the lens fixing base 45 is fixed so that the front surface 45a thereof is parallel to the front surface 10b of the heat block 10. For that purpose, it is also possible to apply a technique in which the front surface 44b of the collimating lens holder 44 is parallel to the heat block front surface 10b using the laser autocollimator 50 and the mechanical hand 52 shown in FIG.

  The condenser lens holder 46 is first bonded and fixed to the lens fixing base 45 fixed as described above, and then the condenser lens 20 is bonded and fixed to the upper surface 46c. The condensing lens holder 46 is formed in a rectangular parallelepiped shape from, for example, an ultraviolet ray transmissive glass. When the adhesive lens holder 46 is bonded and fixed to the front surface 45 a of the lens fixing base 45, the collimating lens holder 44 is attached to the heat block 10. The technique when adhered and fixed to the front surface 10b can be similarly applied. That is, in this case, the front surface 46b of the condensing lens holder 46 is used as a reference surface, and the condensing lens holder 46 is bonded and fixed so that the rear surface 46a serving as the bonding surface is parallel to the lens fixing base front surface 45a with high accuracy. Is done.

  The parallelism between the rear surface 46a and the front surface 46b of the condenser lens holder 46 can be an error of about ± 15 ″. Such high-precision parallelism polishes the rear surface 46a and the front surface 46b. This is possible.

  Next, the condenser lens 20 is adhesively fixed to the upper surface 46c of the condenser lens holder 46 which is adhesively fixed. As described above, the condensing lens 20 has a shape that is long in the horizontal direction. However, the lower surface 20a that serves as an adhesive surface to the condensing lens holder 46 and the upper surface 20b that serves as a reference surface are mutually highly accurate. It is formed to be parallel. In adhering the condenser lens 20 to the condenser lens holder upper surface 46c, the above-described technique when the collimating lens array 18 is adhered and fixed to the upper surface 44c of the collimating lens holder 44 can be similarly applied. That is, in this case, the upper surface 20b of the condensing lens 20 is used as a reference surface, and the condensing lens 20 is bonded so that the lower surface 20a, which is an adhesive surface, is parallel to the upper surface 46c of the condensing lens holder 46 with high accuracy. Fixed.

  The parallelism between the lower surface 20a and the upper surface 20b of the condensing lens 20 can be an error of about ± 15 ″. Such highly accurate parallelism is realized by polishing the lower surface 20a and the upper surface 20b. In addition, the parallelism between the optical surface and the upper surface 20b of the condensing lens 20 that is used as a reference surface can be about ± 15 ″.

  In the structure described above, the lens fixing base 45 and the condenser lens holder 46 correspond to the fixing member in the present invention.

  As described above, the condensing lens 20 is fixed to the condensing lens holder 46 in a state where the optical axis thereof coincides with the core axis of the multimode optical fiber 30 with high accuracy. In addition, the collimating lens array 18 is also fixed with the optical axes of the collimating lenses 11 to 17 parallel to the core axis of the multimode optical fiber 30 with high accuracy as described above. The coupling efficiency to the multimode optical fiber 30 of B1-7 is ensured high.

  Moreover, in the multiplexing laser apparatus of this embodiment, since the GaN-based semiconductor lasers LD1 to LD7 are fixed to the heat block 10 by Sn—Au solder, the heat generated by the GaN-based semiconductor lasers LD1 to LD7 is Heat is radiated to the heat block 10 through the Sn—Au solder having high thermal conductivity. If so, the GaN-based semiconductor lasers LD1 to LD7 are not driven at a high temperature due to poor heat dissipation, and their output and lifetime are prevented from being reduced. Furthermore, in the present embodiment, since the heat block 10 is fixed to the base plate 42 by Sn48-In52 solder, the heat radiation from the heat block 10 to the base plate 42 is also improved. The effect of preventing the decrease in output and life becomes more remarkable.

  Further, in the multiplexing laser device of the present embodiment, the collimator lens array 18 and the condensing lens 20 constituting the condensing optical system are made of a thin layer adhesive with respect to the collimating lens holder 44 and the condensing lens holder 46, respectively. Since it is fixed, unlike the case of fixing with solder, the collimator lens array 18 and the condenser lens 20 do not move due to melting of the solder, and the positional accuracy is kept high. This is also true for the collimating lens holder 44 and the condensing lens holder 46 that are fixed to the heat block 10 and the lens fixing base 45 by the thin layer adhesive, respectively.

  It can be said that the positional accuracy of the heat block 10 and the lens fixing base 45 fixed to the base plate 42 of the package 40 with Sn48-In52 solder tends to be lower than when the adhesive is used. However, even if the positional accuracy of the heat block 10 and the lens fixing base 45 is low, the collimating lens holder 44 and the condenser lens holder 46 are accurately aligned and fixed to each other, and the collimating is performed. If the collimator lens array 18 and the condensing lens 20 are bonded and fixed to the lens holder 44 and the condensing lens holder 46 accurately, the multimode optical fiber 30 of the collimator lens array 18 and the condensing lens 20 can be obtained. High positional accuracy with respect to can be ensured.

  In this embodiment, the melting point (280 ° C.) of the Sn—Au solder for fixing the GaN-based semiconductor lasers LD 1 to 7 and the ferrule 31 are fixed as the solder for fixing the heat block 10 and the lens fixing base 45 to the base plate 42. Sn48-In52 solder having a melting point (117 ° C.) lower than that of Sn-3.5Ag-0.5Cu solder (220 ° C.) is used and heated to a temperature lower than 280 ° C. and 220 ° C. Therefore, even if heat is transmitted to the Sn-Au solder or Sn-3.5Ag-0.5Cu solder at the time of melting, the GaN-based semiconductor lasers LD1 to LD7 and the ferrule 31 move because they are melted. There is no. As described above, when the heat block 10 and the lens fixing base 45 are fixed to the base plate 42, there is no problem even if heat for melting the Sn48-In52 solder is transmitted to the entire package 40. Is easy.

  However, in the present invention, the same solder may be used as the solders used at different times. However, in this case, it is necessary to melt the solder locally for each fixed portion as described above so that heat is not transmitted to the portion already fixed with the solder. In that case, the effect of facilitating solder procurement and management can be obtained.

  Further, in the present embodiment, a heat block 10 having a front surface 10b as a guide surface extending in a direction perpendicular to the core axis of the multimode optical fiber 30 and an upper surface 44c as a guide surface extending in the core axis direction of the optical fiber 30 are provided. Since the collimating lens holder 44 constitutes a fixing member for the collimating lens array 18, when the collimating lens array 18 is fixed, the collimating lens holder 44 is moved along the heat block front surface 10b in a direction perpendicular to the core axis. Further, by moving the collimating lens array 18 along the collimating lens holder upper surface 44c in the core axis direction, the collimating lens array 18 can be easily positioned with respect to the core axis.

  In this embodiment, the lens fixing base 45 having a front surface 45a as a guide surface extending along a direction perpendicular to the core axis of the multimode optical fiber 30, and the upper surface as a guide surface extending in the core axis direction of the optical fiber 30 are used. Since the condensing lens holder 46 provided with 46c constitutes a fixing member for the condensing lens 20, when the condensing lens 20 is fixed, the condensing lens holder 46 is connected to the core shaft along the lens fixing base front surface 45a. The condenser lens 20 can be easily positioned with respect to the core axis by moving in a direction perpendicular to the central axis and moving the condenser lens 20 along the condenser lens holder upper surface 46c in the core axis direction. it can.

  As described above, the collimating lens array 18 and the condensing lens 20 constituting the condensing optical system can be positioned at the optimum position with respect to the core axis of the multimode optical fiber 30, so the multimode optical fiber 30 is As described above, it may be simply fixed to the side wall portion of the package 40 through the ferrule 31. Thus, since there is no need to provide a mechanism for aligning the multimode optical fiber 30 in the package 40, the combined laser device of this embodiment can be formed in a small size.

  The multimode optical fiber 30 may be directly fixed to the side wall portion of the package 40 without using the ferrule 31.

In addition to assembling the multiplexing laser device as described above, the inclination of the collimating lens array 18 and the condensing lens 20 is measured in order to determine whether the assembled laser device has been assembled. In this case, it is also possible to measure the inclination of the collimating lens array 18, the condensing lens 20, etc. using each reference surface. Furthermore, when disassembling and reassembling the combined laser device after assembly is complete, it is also possible to measure the tilt of the collimating lens array 18, the condensing lens 20 and the like using each reference surface. The front surface 10b of the heat block 10 serving as a reference surface for measuring the angle with respect to the reference direction, the front surface 44b and the upper surface 44c of the collimating lens holder 44, the upper surface 18b of the collimating lens array 18, the front surface 45a of the lens fixing base 45, and the condenser lens The front surface 46b and the upper surface 46c of the holder 46 and the upper surface 20b of the condenser lens 20 have a surface roughness Ra of 0.08 μm in order to reflect the laser beam Br emitted from the laser autocollimator 50 without scattering. It is desirable to finish with less than a mirror surface. When the reference surface has such a surface roughness Ra, the angle with respect to the reference direction can be measured with an accuracy of generally about ± 5 ″.

  On the other hand, an adhesive surface to be bonded to the reference surface as described above, specifically, the rear surface 44a of the collimating lens holder 44, the lower surface 18a of the collimating lens array 18, the rear surface 46a of the condensing lens holder 46, and the condensing lens. The lower surface 20a of 20 is preferably formed to be rougher than the reference surface in order to allow the adhesive to permeate well with the reference surface. For example, when the surface roughness Ra of the reference surface is less than 0.08 μm as described above, the surface roughness Ra of the bonding surface is preferably in the range of 0.15 μm to 0.35 μm. The surface roughness Ra can be measured by, for example, a stylus roughness measuring instrument.

  In this embodiment, the mounting surface of the fixing means and the reference surface are set parallel to each other. However, the present invention is not limited to this, and the reference surface is set to form a predetermined angle, for example, 90 ° with respect to the mounting surface. It does not matter. The same applies to the adhesive surface and the reference surface of the adhesive component.

  Further, the glass used for the collimating lens holder 44 is made of AlN which is a material of the heat block 10 in order to reduce the thermal stress generated in the bonded portion with the heat block 10 due to a temperature change received during use or storage of the apparatus. It is desirable to use a material having a similar linear expansion coefficient. Similarly, it is desirable that the glass used for the collimating lens array 18 has a linear expansion coefficient close to that of the material of the collimating lens holder 44. This is also true between the lens fixing base 45, the condenser lens holder 46, and the condenser lens 20.

  In the embodiment described above, AlN is used as the material of the heat block 10 and the lens fixing base 45, but Cu or Cu alloy can also be suitably used as this material. Further, the heat block 10 and the lens fixing base 45 may be integrally formed.

  In the embodiment described above, the collimating lens array 18 and the condensing lens 20 are employed. For example, as shown in Patent Document 1, one condensing lens having both functions is employed. There has also been proposed a combined laser device, and the present invention is similarly applicable to a laser device using such a condensing lens.

  Further, in the embodiment described above, the heat block 10 and the lens fixing base 45 are attached to the upper surface of the base plate 42 fixed to the bottom surface of the package 40. However, as in the embodiment shown in FIGS. The plate 42 may be omitted, and the heat block 10 and the lens fixing base 45 may be fixed directly on the bottom surface of the package 40.

  Further, the embodiment configured as a combined laser light source has been described above. However, the present invention is not limited thereto, and one laser beam emitted from one semiconductor laser is condensed and coupled to an optical fiber. The present invention can be similarly applied to the configured laser apparatus.

The partially broken top view of the combining laser apparatus by one Embodiment of this invention Partially broken side view of the above combined laser device Partial front view of the above combined laser device The figure explaining the assembly method of the said combining laser apparatus The figure explaining the assembly method of the said combining laser apparatus The figure explaining the assembly method of the said combining laser apparatus The figure explaining the assembly method of the said combining laser apparatus The partially broken top view of the combining laser apparatus by another embodiment of this invention FIG. 8 is a partially broken side view of the multiplexing laser device of FIG.

Explanation of symbols

10 Heat block
11-17 Collimating lens
18 Collimating lens array
20 Condensing lens
30 Multimode optical fiber
40 packages
41 Package lid
42 Base plate
44 Collimating lens holder
45 Lens mount
46 Condenser lens holder
50 Laser autocollimator
52 Mechanical Hand LD1-7 GaN Semiconductor Laser B1-7 Laser Beam B Combined Laser Beam

Claims (7)

A semiconductor laser,
With optical fiber,
A condensing optical system that condenses the laser beam emitted from the semiconductor laser and irradiates the incident end of the optical fiber;
In the laser apparatus comprising the condensing optical system and the semiconductor laser fixedly housed therein, and the optical fiber having a package in which the incident end is fixed to face the condensing optical system,
A laser apparatus, wherein an optical component constituting the condensing optical system is fixed to the package or a fixing member fixed thereto by a thin layer adhesive, and the semiconductor laser is fixed by solder.   2. The laser device according to claim 1, wherein the fixing member to which the semiconductor laser is fixed and the fixing member to which the optical component is fixed are both fixed to the package by soldering.   The holder is fixed to the fixing member by a thin layer adhesive, and an optical component constituting the condensing optical system is fixed to the holder by a thin layer adhesive. Laser device. A plurality of elements including the semiconductor laser are fixed to a package or a fixing member fixed thereto by solder,
4. The laser device according to claim 1, wherein the same solder is used as each of the solders for fixing the elements. A plurality of elements including the semiconductor laser are fixed to a package or a fixing member fixed thereto by solder,
4. The laser device according to claim 1, wherein solders for fixing these elements are used having different melting points.   6. A method of assembling a laser apparatus according to claim 1, wherein the element fixed by the thin layer adhesive is fixed after the element fixed by the solder is fixed. Assembly method.   When a plurality of types of solder having different melting points are used as the solder, the fixing operation using the second solder having the lower melting point is performed after the fixing operation using the first solder having the higher melting point is completed. 7. The method for assembling a laser device according to claim 6, wherein the second solder is melted at a temperature lower than the melting point of the solder.

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