TWI706577B - Method for manufacturing long-period fiber grating - Google Patents

Abstract

The present invention discloses a method for manufacturing a long-period fiber grating. The method includes: arranging a shielding member with a long-period structure on an optical fiber; irradiating a laser to the optical fiber through the shielding member so that the optical fiber corresponds to the long-period structure The surface of the part is melted, but not the surface of the part corresponding to the long-period structure; and the fiber is wet-etched.

Description

Method for manufacturing long-period fiber grating

The invention relates to a method for manufacturing a fiber grating, and particularly relates to a method for manufacturing a long-period fiber grating.

Please refer to the Republic of China Invention Patent Publication No. I394993, which discloses a method for fabricating a variable-length-period fiber grating which includes: removing the fiber coating layer of the fiber in advance, and etching to reduce the thickness of the coating layer of the fiber; forming on the surface of the substrate Metal layer; coating a photoresist layer on the surface of the metal layer and soft-baking; heat the photoresist layer again after exposing the photoresist layer; remove the unexposed photoresist layer through a developer to form a lower geometric structure on the surface of the metal layer; The optical fiber is fixed on the lower geometric structure; another photoresist layer is coated on the optical fiber and the lower geometric structure again, and the photoresist layer is exposed and developed to form an upper geometric structure stacked on the lower geometric structure, whereby the upper geometric structure and The lower geometric structure is formed on the outer surface of the optical fiber to form a photoresist layer with a zigzag geometric structure; the optical fiber and the photoresist layer on the outer surface are heated; and the photoresist layer on the outer surface of the optical fiber is separated from the metal layer by a separating liquid to achieve adjustable The finished long-period fiber grating.

Please also refer to the Republic of China Invention Patent Publication No. I484232, which discloses a method for fabricating a variable-length-period fiber grating. This method can improve the process efficiency and includes: removing the fiber coating layer of the fiber in advance, and etching to reduce the thickness of the coating layer of the fiber Up to 10 to 125μm; the sacrificial layer is formed by physical vapor deposition, chemical vapor deposition, or bonding on the surface of the substrate; the first geometric structure is printed on the sacrificial layer by a screen printing machine, and the first geometric structure is Continuously arranged bumps; fix the optical fiber on the first geometric structure; use the screen printing machine to print the second geometric structure on the first geometric structure, and the second geometric structure and the first geometric structure cover the optical fiber together The outer surface; and the use of etching solution to remove the sacrificial layer.

Please refer to the Republic of China Invention Patent Announcement No. I406022, which discloses a method for fabricating a tunable variable-length-period fiber grating. The method includes: removing the fiber coating layer of the fiber in advance, and etching to reduce the thickness of the coating layer of the fiber to 10 to 125 μm; The metal layer is formed by physical or chemical vapor deposition on the surface of the substrate; the photoresist material is coated on the surface of the metal layer to form the photoresist layer; the photoresist layer is heated to above the glass transition temperature to volatilize the remaining in the photoresist layer Solvent and harden the photoresist layer; partially expose the photoresist layer, and after the exposure is completed, heat the photoresist layer to above the glass transition temperature; remove the unexposed photoresist layer through a developer solution to develop the photoresist layer; Fix the optical fiber on the photoresist layer; coat another photoresist layer on the optical fiber and the photoresist layer so that the two photoresist layers together form a zigzag structure covering the outer surface of the fiber; heat the fiber and the photoresist on the outer surface of the fiber Layer, volatilize the solvent in the light-emitting resist layer, and let the photoresist flow to fill the gap; form several metal modulation layers on the outer surface of the optical fiber, and each metal modulation layer is respectively filled into the gap formed by the zigzag structure; The liquid makes the photoresist layer and the metal modulating layer on the outer surface of the optical fiber separate from the metal layer; and removes the photoresist layer on the outer surface of the optical fiber.

Please refer to the Republic of China Invention Patent Publication No. I418865 again, which discloses a method for fabricating fiber gratings. This method includes: removing the fiber coating layer of the optical fiber in advance, and etching to reduce the thickness of the coating layer of the optical fiber to 10 to 125 μm; using physical or chemical gas Phase deposition is deposited on the surface of the substrate to form a metal layer; a photoresist material is coated on the surface of the metal layer to form a photoresist layer; the photoresist layer is heated to above the glass transition temperature to volatilize the solvent remaining in the photoresist layer and light The resist layer is hardened; the resist layer is partially exposed and then heated again to above the glass transition temperature; the unexposed resist layer is removed by a developer to develop and shape the resist layer; the optical fiber is fixed on the resist layer; The optical fiber and the photoresist layer are coated with another photoresist layer so that these photoresist layers together form a zigzag structure covering the outer surface of the optical fiber; the optical fiber and the photoresist layer located on the outer surface of the optical fiber are heated to volatilize the Solvent and let the photoresist flow to fill the gap; use the separating liquid to separate the photoresist layer and the metal layer on the outer surface of the optical fiber; and cover the outer surface of the optical fiber with polymer polymer and fill the zigzag structure formed by Gap to form a protective layer.

It can be seen from the above that the conventional method uses an etching method to reduce the thickness of the optical fiber. However, due to the insufficient etching depth, the transmission loss of the optical fiber cannot be increased, resulting in poor optical fiber sensitivity. On the other hand, the conventional method requires multiple cumbersome manufacturing processes, resulting in overall time-consuming and lengthy. Therefore, it is indeed necessary to propose improvements to the above problems.

One purpose of the present invention is to solve the problem of poor optical fiber transmission loss obtained by the conventional method.

Another object of the present invention is to solve the problem of poor sensitivity of the optical fiber obtained by the conventional method.

Another purpose of the present invention is to solve the problem that the conventional method is too cumbersome.

Therefore, the present invention discloses a method for manufacturing a long-period fiber grating. The method includes: arranging a shielding member with a long-period structure on an optical fiber; irradiating a laser to the optical fiber through the shielding member to make the optical fiber correspond to the long-period The surface of the part of the structure is melted, but the surface of the part corresponding to the long-period structure is not melted; and the fiber is wet-etched.

Preferably, the laser is an excimer laser.

Preferably, the laser is Ar ₂ *, Kr ₂ *, F ₂ *, Xe ₂ *, ArF, KrF, XeBr, XeCl, XeF, or KrCl.

Preferably, the laser energy is 10 to 15 mJ and the frequency is 50 to 150 Hz.

Preferably, the laser travel speed is 0.05 to 0.3 mm/s.

Preferably, the optical fiber is wet-etched in advance before the mask is set.

Preferably, before setting the shielding member, a coat layer outside the optical fiber is removed.

Preferably, the thickness of the part of the optical fiber corresponding to the long-period structure after wet etching is 15 to 25 μm, and the thickness of the part not corresponding to the long-period structure after wet etching is 40 to 45 μm.

According to the present invention, the combination of laser irradiation and wet etching can enhance the etching depth (that is, reduce the thickness of the optical fiber) to improve the transmission loss of the optical fiber, thereby increasing its sensitivity. In addition, the proposed method can be completed by laser irradiation and wet etching, without the need for a photoresist development process, which can improve operation convenience and shorten the process time.

(S1 to S5)‧‧‧Step

(1)‧‧‧Optical fiber

(11, 12)‧‧‧Location

(2)‧‧‧Outer layer

(3, 4)‧‧‧Mask

(31, 41)‧‧‧Long period structure

(D1 to D3)‧‧‧Thickness

(R)‧‧‧Laser

(S)‧‧‧Movement direction

FIG. 1 is a flowchart illustrating a method of manufacturing a long period fiber grating according to an embodiment of the present invention.

Figures 2A to 2E are a series of cross-sectional views showing the above method.

Figure 3 is a three-dimensional schematic diagram showing the mask used in the above method.

Figure 4 is an optical microscope photo showing that the surface of the optical fiber is in a molten state after being irradiated by a laser.

Figure 5 is an optical microscope photograph showing the structure of the optical fiber after wet etching.

In order to make the above and/or other objectives, effects, and features of the present invention more obvious and understandable, the preferred embodiments are specifically described below in detail: An embodiment of the present invention provides a method for manufacturing a long-period fiber grating. The method can strengthen the etching depth and improve the transmission loss and sensitivity of the optical fiber.

First, as shown in Fig. 1 and Fig. 2A, a coat layer (2) outside an optical fiber (1) is removed. Step (S1) allows the optical fiber (1) covered by the outer layer (2) to be exposed, which facilitates subsequent processing of the optical fiber (1). The removal of the outer layer (2) can be achieved by peeling or grinding; specifically, the peeling can be accomplished by clamping the outer layer (2) with pliers and sliding along one end of the optical fiber (1), and grinding can be done by rubbing the outer layer with sandpaper back and forth. The clothing layer (2) is completed.

Next, as shown in Fig. 1 and Fig. 2B, the optical fiber (1) is wet-etched in advance. The step (S2) can reduce the thickness (D1) of the optical fiber (1), which can save the time required for subsequent steps; preferably, the thickness (D1) is reduced to 55 to 70 μm. In addition, during pre-wet etching, the optical fiber (1) can be immersed in an etching solution, and the etching solution can be a hydrofluoric acid solution but is not limited thereto. In fact, for example, BOE (buffered oxide etch), preferably BOE 6:1 ( 49% HF aqueous solution and 40% NH ₄ F aqueous solution are mixed in a volume ratio of 1:6).

Next, as shown in Figs. 1 and 2C, a mask (3) with a long period structure (31) is set on the optical fiber (1). The term "long-period structure" used in the text refers to a structure composed of a plurality of periodically arranged light-transmitting regions (Figure 3); the width of each light-transmitting region can be determined by the period of the subsequently formed grating, preferably 1 to 5mm. Furthermore, in order to stabilize the position of the optical fiber (1), another shielding member (3) as described above can be arranged so that the optical fiber (1) is arranged between these shielding members (3, 4).

Then, as shown in Figure 1 and Figure 2D, irradiate a laser (R) to the optical fiber (1) through the shielding member (3), and the laser (R) irradiation can make the optical fiber (1) correspond to the long-period structure (31) The surface of the part (11) is melted, but not the surface of the part (12) corresponding to the long period structure (31). Please refer to Figure 4 to show the sintered surface of the optical fiber (1) with an optical microscope. Step (S4) can cause the laser (R) to generate thermal effect on the surface of the optical fiber (1) to melt it, so that after the subsequent wet etching step (S5), the melted part (11) and the unsmelted part (12) ) A difference in etching depth is formed. In order to distribute the depth difference along the axis of the optical fiber (1), the optical fiber (1) can be rotated in situ when the laser (R) is irradiated, or the laser (R) can be rotated along the circumference of the optical fiber (1). In addition, the laser (R) can be an excimer laser, but is not limited thereto. In fact, for example, Ar ₂ *, Kr ₂ *, F ₂ *, Xe ₂ *, ArF, KrF, XeBr, XeCl, XeF or KrCl. Furthermore, the parameters of the laser (R) can be determined by the subsequent etching depth; preferably, the energy of the laser (R) is 10 to 15 mJ, such as 12 mJ, and the frequency is 50 to 150 Hz, such as 100 Hz. Since the laser (R) presents a beam of light, in order to form multiple melting parts (11) on the optical fiber (1), the laser (R) can move in one direction (S) relative to the optical fiber (1), and the moving speed (or The "travel speed") is preferably 0.05 to 0.3 mm/s, for example 0.2 mm/s.

Finally, as shown in Figure 1 and Figure 2E, wet etch the optical fiber (1). This step (S5) can further reduce the thickness (D2, D3) of the optical fiber (1); preferably, reduce the thickness (D2) of the part (11) corresponding to the long-period structure (31) to 15 to 25 μm, reducing the non-corresponding The thickness (D3) of the part (12) of the long-period structure (31) is 40 to 45 μm. Please refer to Figure 5 to show the structure of the optical fiber (1) after wet etching with an optical microscope. In addition, during wet etching, the optical fiber (1) can also be immersed in an etching solution, and the etching solution can be a hydrofluoric acid solution but is not limited thereto. In fact, for example, BOE, preferably BOE 6:1.

According to the above-mentioned embodiment, long periodicity can be fabricated in the optical fiber, so that the optical fiber has a good periodic structure and resonance wavelength. In addition, the combination of laser irradiation and wet etching can enhance the etching depth, thereby improving the transmission loss of the optical fiber and increasing the sensitivity. Moreover, the proposed method can be completed by simply using laser irradiation and wet etching, and does not require complicated processes (such as photoresist development process). In this way, the convenience of producing long-period gratings can be improved and the production time can be shortened.

However, the above are only preferred embodiments of the present invention, but cannot be used to limit the scope of implementation of the present invention; therefore, all simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the description of the invention, All are still within the scope of the invention patent.

(1)‧‧‧Optical fiber

(11, 12)‧‧‧Location

(D2, D3)‧‧‧Thickness

Claims (9)

A method for manufacturing a long-period fiber grating includes: arranging a shielding member with a long-period structure on an optical fiber; irradiating a laser through the shielding member to the optical fiber, and the laser generates a thermal effect on the surface of the optical fiber to make The surface of the optical fiber corresponding to the long-period structure is melted while the surface of the optical fiber does not correspond to the long-period structure. The laser energy is 10 to 15 mJ and the frequency is 50 to 150 Hz; and wet etching For the optical fiber, the sintered part and the unsintered part on the surface of the optical fiber have a difference in etching depth. The manufacturing method according to claim 1, wherein the laser is an excimer laser. The manufacturing method according to claim 1, wherein the laser is selected from Ar ₂ *, Kr ₂ *, F ₂ *, Xe ₂ *, ArF, KrF, XeBr, XeCl, XeF, and KrCl Group. The manufacturing method according to claim 1, wherein the laser traveling speed is 0.05 to 0.3 mm/s. According to the manufacturing method described in claim 1, before the step of setting the mask member, it further comprises: pre-wetting the optical fiber. According to the manufacturing method described in claim 1, before the step of setting the shielding member, it further includes: removing a coat layer outside the optical fiber. According to the manufacturing method described in claim 1, before the step of setting the shielding member, it further includes: removing a coating layer outside the optical fiber; and pre-wet etching the optical fiber. The manufacturing method according to claim 1, wherein the thickness of the part of the optical fiber corresponding to the long-period structure after the wet etching is 15 to 25 μm, and the thickness of the part that is not corresponding to the long-period structure after the wet etching is 40 to 45μm. The manufacturing method according to claim 1, wherein the laser energy is 12 mJ, the frequency is 50 to 100 Hz, and the traveling speed is 0.2 mm/s.

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