CN212462338U - Coupling output structure of terahertz quantum cascade laser - Google Patents

Abstract

The utility model relates to a coupling output structure of terahertz quantum cascade laser instrument now, including terahertz quantum cascade laser instrument now, first off-axis parabolic mirror, second off-axis parabolic mirror, the focus of first off-axis parabolic mirror is located in the front end face of terahertz quantum cascade laser instrument now, is used for collecting and the collimation the laser that terahertz quantum cascade laser instrument sent now to form first quasi parallel light beam; the second off-axis parabolic reflector is located in the rear end face of the terahertz quantum cascade laser and used for collecting and collimating laser light emitted by the terahertz quantum cascade laser and forming a second quasi-parallel light beam. The utility model discloses can realize the high-efficient coupling output of laser of two terminal surfaces.

Description

Coupling output structure of terahertz quantum cascade laser

Technical Field

The utility model relates to a terahertz laser technical field especially relates to a terahertz quantum cascades coupling output structure of laser instrument now.

Background

Terahertz (THz) Quantum Cascade Laser (QCL) is a very important compact laser source in the THz frequency band, and has the characteristics of small volume, stable performance, high energy conversion efficiency, long service life and the like. Among THz QCLs of various shapes, ridge stripe devices are the most common one. Because the size of the laser ridge in the thickness direction is smaller than the laser wavelength, the laser emitted by the THz QCL end surface presents certain divergence, in order to improve the output beam of the laser, the ridge structure or the laser output end surface can be subjected to process improvement, and the quality of the output laser beam is improved by preparing a structural grating or an end surface microstructure, but the method increases the process preparation difficulty of the device, and meanwhile, the final output optical power of the device suffers certain loss due to the change of the ridge structure; another method is to add a micro optical structure such as a high-resistance silicon lens on the end face of the ridge stripe laser to improve the beam quality, but because the high-resistance silicon lens also has a certain absorption to the THz laser, there is a certain loss in the optical power finally output by the improved device compared with the optical power output by the improved front end face. Therefore, there is a need to find better methods of coupling out that reduce losses.

In addition, when the ridge stripe laser works, the front end face and the rear end face of the ridge stripe laser have symmetry and the same property, and the frequency and the power of output laser are basically consistent. However, in the practical application process, only one end face of the laser is usually coupled, and the adopted coupling output method needs to operate and move the position of the coupling optical element under vacuum, so that the implementation mode is complex, the low-temperature dewar air leakage condition is easy to occur, and the laser output by the other end face is wasted; although there is a method of increasing the total power of the light-emitting end face by evaporating the medium/metal high-reflection film on the other end face, due to the low quality of the preparation process of the high-reflection film and the reflection loss of the laser output end face, the improvement can only obtain the laser power of about 1.4 times of single-side output, and still 0.6 times of single-side output power is wasted. The structure of simultaneous coupling-out of two end faces of the laser is not reported at present. Therefore, in order to realize effective coupling of the output power of the other end surface, so that the total output power of the laser reaches 2 times of the single-surface output power, the problems of efficient coupling and simultaneous output of the laser light output by the two end surfaces of the ridge stripe laser are urgently needed to be solved.

SUMMERY OF THE UTILITY MODEL

The utility model provides a terahertz quantum cascades coupling output structure of laser instrument now can realize the high-efficient coupling output of laser of two terminal surfaces.

The utility model provides a technical scheme that its technical problem adopted is: the coupling output structure of the terahertz quantum cascade laser comprises the terahertz quantum cascade laser, a first off-axis parabolic reflector and a second off-axis parabolic reflector, wherein the focus of the first off-axis parabolic reflector is located in the front end face of the terahertz quantum cascade laser and is used for collecting and collimating laser light emitted by the terahertz quantum cascade laser and forming a first quasi-parallel light beam; the second off-axis parabolic reflector is located in the rear end face of the terahertz quantum cascade laser and used for collecting and collimating laser light emitted by the terahertz quantum cascade laser and forming a second quasi-parallel light beam.

The focus of the first off-axis parabolic reflector is coincided with the center of the front end face of the terahertz quantum cascade laser; the focus of the second off-axis parabolic reflector coincides with the center of the rear end face of the terahertz quantum cascade laser.

The terahertz quantum cascade laser is packaged on a heat sink, and the heat sink, the first off-axis parabolic reflector and the second off-axis parabolic reflector are mounted on a heat conducting sample frame.

The terahertz quantum cascade laser is of a single-sided metal waveguide structure or a semi-insulating surface plasma structure.

The working frequency range of the terahertz quantum cascade laser covers 1.2-5.2 THz.

The diameter focal length ratio of the first off-axis parabolic reflector and the diameter focal length ratio of the second off-axis parabolic reflector are both 0.5-1.

The reflecting angles of the first off-axis parabolic reflector and the second off-axis parabolic reflector are both 90 degrees, and the reflecting surfaces are both gold-plated reflecting surfaces.

The heat sink is made of gold-plated pure copper material.

The heat conduction sample rack is made of gold-plated pure copper material.

Advantageous effects

Since the technical scheme is used, compared with the prior art, the utility model, have following advantage and positive effect:

(1) the coupling output structure of the terahertz quantum cascade laser adopts the gold-plated reflecting surface, so that the terahertz laser has small reflection loss and high coupling efficiency;

(2) the coupling output structure of the terahertz quantum cascade laser adopts a double-reflector coupling structure, can couple and output the output lasers of the front end surface and the rear end surface of the laser simultaneously, and greatly improves the effective output power of the laser compared with the existing external coupling output structure;

(3) the utility model discloses a terahertz quantum cascade laser's coupling output structure can export simultaneously two bundles of accurate parallel terahertz laser that have the same property, does not need the beam splitting, just can act on target system simultaneously, has reduced the optical element of system, has improved laser utilization efficiency, is convenient for simultaneously effectively contrast the system that two bundles of laser acted on respectively.

(4) The utility model discloses a terahertz quantum cascade laser's coupling output structure now has compact structure, and is reliable and stable, and no vacuum removes the part and calibrates, greatly reduced the risk of vacuum gas leakage in the laser instrument use.

Drawings

Fig. 1 is a schematic structural diagram of a coupling output structure of a terahertz quantum cascade laser according to the present invention;

fig. 2 is a graph of the effective pulse peak output power of the terahertz quantum cascade laser of the preferred embodiment of the present invention at a temperature of 6K, in which a solid line corresponds to the total output power of two end faces, and a dot-dash line corresponds to the output power of a front end face.

Detailed Description

The present invention will be further described with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes and modifications of the present invention may be made by those skilled in the art after reading the teachings of the present invention, and these equivalents also fall within the scope of the appended claims.

The utility model discloses an embodiment relates to a terahertz quantum cascade laser's coupling output structure now, and it can realize the high-efficient coupling output of laser of two terminal surfaces.

Fig. 1 shows an implementation apparatus of a terahertz quantum cascade laser coupled output structure according to a preferred embodiment of the present invention, including: terahertz quantum cascade laser 1, heat sink 2, first off-axis parabolic reflector 3, second off-axis parabolic reflector 4 and heat conducting sample holder 5

As shown in fig. 1, a focus of the first off-axis parabolic mirror 3 coincides with a center of a front end surface 11 of the terahertz quantum cascade laser 1, a first quasi-parallel light beam 6 is formed after laser coupling is output to the front end surface 11, a focus of the second off-axis parabolic mirror 4 coincides with a center of a rear end surface 12 of the terahertz quantum cascade laser 1, and a second quasi-parallel light beam 7 is formed after laser coupling is output to the rear end surface 12.

In the present embodiment, the ratio of the focal length of the diameter of the first off-axis parabolic mirror 3 to the focal length of the diameter of the second off-axis parabolic mirror 4 is preferably 0.5 to 1, and the ratio of the focal length of the diameter is preferably 0.52.

Further, the reflecting surfaces of the first off-axis parabolic reflector 3 and the second off-axis parabolic reflector 4 are 90-degree off-axis gold-plated reflecting surfaces.

In the present embodiment, the terahertz quantum cascade laser 1 is a single-sided metal waveguide structure or a semi-insulating surface plasmon structure.

Further, the length of the terahertz quantum cascade laser 1 is 4mm, the width is 300 μm, and the thickness is 200 μm.

Further, the lasing frequency of the terahertz quantum cascade laser 1 is 4.3 THz.

In a preferred embodiment, as shown in fig. 2, the total pulse peak output power of the two end faces of the terahertz quantum cascade laser 1 is 1.05mW, the pulse peak output power of the front end face is 0.53mW, the power meter used for measuring the power is TK 100, the diameter of the sensitive area of the power meter is 30mm, and the laser driving current density corresponding to the pulse peak output power is 1230A-cm^-2Thus, the total output power of the two end faces is close to 2 times of the single-face output power.

In the present embodiment, the heat sink 2 is a surface gold-plated pure copper material, and has dimensions of 4mm in width, 26mm in length, and 4mm in thickness. The heat conducting sample holder 5 is made of gold-plated pure copper material.

The specification also provides a packaging method of the terahertz quantum cascade laser coupling output structure, which is used for manufacturing the laser coupling output.

The method specifically comprises the following steps:

s01: the terahertz quantum cascade laser 1 is packaged at the right center of the heat sink 2 through a high-purity indium material with the purity of 99.99%, and the front end face 11 and the rear end face 12 of the packaged terahertz quantum cascade laser are aligned with the length edge of the heat sink 2;

s02: installing the heat sink 2 on the heat conduction sample frame 5 according to the designed position, wherein the central point of the heat sink 2 is positioned in the right center of the heat conduction sample frame 5 after installation;

s03: designing the diameter of a first off-axis parabolic reflector 3 and a second off-axis parabolic reflector 4 to be 10mm, the focal length to be 5.2mm, and the height of the focal point to the bottom surface of a reflector body to be 4mm, respectively packaging the first off-axis parabolic reflector 3 and the second off-axis parabolic reflector 4 on a heat conduction sample rack 5 by adopting a low-temperature adhesive, wherein the thickness of the adhered low-temperature adhesive is 0.1mm, and at the moment, the focal point height of the first off-axis parabolic reflector 3 is 4.1mm, so that the height of the center of a front end surface 11 of a terahertz quantum cascade laser 1 is half of the thickness of a device and is 100 mu m, and the thickness of a heat sink is 4.1mm, and the height of the focal point of the first off-axis parabolic reflector 3 is the same as that of the center of a rear end surface 12 of the terahertz quantum cascade laser 1 is the same as that of the focal point of the second off-axis parabolic reflector;

s05: before the low-temperature adhesive material is solidified, the center of the front end surface 11 and the center of the rear end surface 12 of the terahertz quantum cascade laser 1 are respectively aligned with the optical axis center line of the first off-axis parabolic reflector 3 and the optical axis center line of the second off-axis parabolic reflector 4 by adopting a microscope marking alignment method, so that the center of the front end surface 11 is ensured to be coincided with the focus of the first off-axis parabolic reflector 3, the center of the rear end surface 12 is coincided with the focus of the second off-axis parabolic reflector 4, the alignment process is kept until the low-temperature adhesive material is solidified and formed, and the keeping time is 30 minutes.

The utility model provides a coupling output structure of terahertz quantum cascade laser, which adopts a gold-plated reflecting surface, has small reflection loss to terahertz laser and high coupling efficiency; the double-reflector coupling structure is adopted, the output lasers of the front end surface and the rear end surface of the laser can be coupled and output at the same time, and compared with the existing external coupling output structure, the effective output power of the laser is greatly improved; the structure can simultaneously output two beams of quasi-parallel terahertz lasers with the same property, can simultaneously act on a target system without beam splitting, reduces optical elements of the system, improves the utilization efficiency of the lasers, and is convenient for effective comparison of systems respectively acted by the two beams of lasers; the structure has the advantages of compact structure, stability, reliability, no vacuum moving part for calibration, and greatly reduced risk of vacuum air leakage in the use process of the laser.

Claims (9)

1. A coupling output structure of a terahertz quantum cascade laser comprises a terahertz quantum cascade laser (1), a first off-axis parabolic reflector (3) and a second off-axis parabolic reflector (4), and is characterized in that the focus of the first off-axis parabolic reflector (3) is located in the front end face (11) of the terahertz quantum cascade laser (1) and used for collecting and collimating laser light emitted by the terahertz quantum cascade laser (1) and forming a first quasi-parallel light beam (6); the second off-axis parabolic reflector (4) is located in the rear end face (12) of the terahertz quantum cascade laser and used for collecting and collimating laser light emitted by the terahertz quantum cascade laser (1) and forming a second quasi-parallel light beam (7).

2. The coupling-out structure of the terahertz quantum cascade laser according to claim 1, wherein the focus of the first off-axis parabolic mirror (3) coincides with the center of the front end face (11) of the terahertz quantum cascade laser (1); the focus of the second off-axis parabolic reflector (4) is coincided with the center of the rear end face (12) of the terahertz quantum cascade laser (1).

3. The coupling-out structure of the terahertz quantum cascade laser according to claim 1, wherein the terahertz quantum cascade laser (1) is packaged on a heat sink (2), and the heat sink (2), the first off-axis parabolic mirror (3) and the second off-axis parabolic mirror (4) are mounted on a heat-conducting sample holder (5).

4. The coupling-out structure of the terahertz quantum cascade laser according to claim 1, wherein the terahertz quantum cascade laser (1) is a single-sided metal waveguide structure or a semi-insulating surface plasmon structure.

5. The coupling-out structure of the terahertz quantum cascade laser device as claimed in claim 1, wherein the working frequency range of the terahertz quantum cascade laser device (1) covers 1.2-5.2 THz.

6. The coupling-out structure of the terahertz quantum cascade laser as claimed in claim 1, wherein the diameter focal length ratio of the first off-axis parabolic mirror (3) and the diameter focal length ratio of the second off-axis parabolic mirror (4) are both between 0.5 and 1.

7. The coupling-out structure of the terahertz quantum cascade laser according to claim 1, wherein the reflection angles of the first off-axis parabolic mirror (3) and the second off-axis parabolic mirror (4) are both 90 degrees, and the reflection surfaces are both gold-plated reflection surfaces.

8. The coupling-out structure of the terahertz quantum cascade laser as claimed in claim 3, wherein the heat sink (2) is a surface gold-plated pure copper material.

9. The coupling-out structure of the terahertz quantum cascade laser as claimed in claim 3, wherein the heat conducting sample holder (5) is a pure copper material with gold-plated surface.

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