KR20040070094A - Laser module - Google Patents

Abstract

PURPOSE: A laser module having a light collection optical system is provided to enhance the reliability by preventing the inside of the laser module due to particles adhered on a coating layer of the optical fiber. CONSTITUTION: A laser module includes a light collection optical system(12), an optical fiber(13), a fixing unit, a first package, and an incident section protection unit. The fixing unit fixes a semiconductor laser element(LD), the light collection optical system, and the optical fiber to a relative position coupled to an incident section of the optical fiber. The first package(P1) is used for sealing up the semiconductor laser element. The incident section protection unit is used for protecting the incident section of the optical fiber from the atmosphere.

Description

LASER MODULE {LASER MODULE}

TECHNICAL FIELD The present invention relates to a laser module, and more particularly, to a laser module having a semiconductor laser element, an optical fiber, and a condensing optical system for coupling a laser beam emitted from the semiconductor laser element to one end surface of the optical fiber.

Conventionally, a semiconductor laser element housed in a package, an optical fiber fixed to the package with one end (light incidence end face) facing the inside of the package, and a laser beam emitted from the semiconductor laser element emit light BACKGROUND OF THE INVENTION A laser module comprising a light converging optical system coupled to a surface is generally known as an optical communication component as a so-called pigtail type laser module.

In the laser module, in order to stably maintain the optically coupled state of the semiconductor laser and the light incidence end surface of the optical fiber in a micrometer order, the optical fiber and the condensing optical system or the like are usually used for bonding means such as solder, welding or adhesive. It is fixed using.

Moreover, in the communication laser module, in order to prevent the laser deterioration due to moisture of the outside air, the sealing of the package is generally carried out in a structure represented by a so-called CAN package, which is a sealing structure that protects the semiconductor laser element and the laser end surface. As representative. In this laser module, there is a problem that contaminants remaining in the hermetically sealed package adhere to optical components such as the emission end face of the semiconductor laser element, the condensing optical system, and the optical fiber, thereby degrading the laser characteristics. In particular, the effect (dust collecting effect) which a substance adheres in the part with high light density is remarkable. In addition, in a laser module having a semiconductor laser device that emits a laser beam having a wavelength of 350 to 500 nm (400 nm band) such as a GaN-based semiconductor laser device, the photon energy is high and a photochemical reaction with the substance is more likely to occur. Since it becomes easier, the dust collection effect is more remarkable.

As one of the contaminants, hydrocarbon compounds mixed in the atmosphere of the manufacturing process may be cited, and it is known that the hydrocarbon is polymerized or decomposed by laser light, and the decomposition product adheres to hinder the improvement of the output.

In addition, it is disclosed that the low molecular siloxane floating in the air reacts with oxygen in a photochemical reaction by ultraviolet rays, and deposits and adheres to the optical glass parts in the form of SiOx. Therefore, the periodicity of the "window" member in contact with the atmosphere is disclosed. Phosphorus exchange is recommended (for example, refer patent document 1).

Thus, various proposals have been made to prevent this dust collection effect. For example, it is proposed to mix oxygen for the purpose of decomposing a hydrocarbon compound or the like into a sealing gas of 100 ppm or more (see Patent Document 2, for example).

Moreover, in the optical system which irradiates an optical component with the ultraviolet-ray below 400 nm, it is proposed to make the atmosphere of an optical component into 99.9% or more nitrogen (for example, refer patent document 3).

It is also known that degassing the inside of the package immediately before sealing the package is effective in preventing the dust collection effect.

[Patent Document 1] Japanese Patent Application Laid-Open No. 11-54852

[Patent Document 2] US Patent 5392305

[Patent Document 3] Japanese Patent Application Laid-Open No. 11-167132

However, in the case of a laser module having an optical fiber in which a primary coating made of UV curable resin and a second coating made of a polymer is applied, and the optical fiber is fixed to the package, a degassing treatment is performed with the optical fiber fixed to the package. As a result, the fiber coating is present in the degassing apparatus, and degassing components are generated from the coating during the degassing treatment, and the inside of the module is contaminated by this gas.

In order to prevent this contamination, it is considered to remove all the coating of the optical fiber in advance, but since the optical fiber without the coating is easily broken, it is difficult to handle and its practicality is low.

In view of the above circumstances, an object of the present invention is to provide a laser module and a method of manufacturing the same, which can obtain high reliability by suppressing adhesion of contaminants.

1 is a side sectional view of a laser module of a first embodiment;

2 is another example of a glass block seal;

3 is another example of a glass block seal;

4 is a schematic diagram of a sealing form (part 1) of a laser module according to a second embodiment;

5 is a schematic view of the sealing form of the laser module according to the second embodiment (No. 2);

6 is a side cross-sectional view of the laser module of the embodiment of the pattern (1),

7 is an enlarged view of a part of the laser module shown in FIG. 6;

8 is a side cross-sectional view of the laser module of the embodiment of the pattern 5;

9 is a plan view of the laser module of the embodiment of the pattern 7,

10 is a side cross-sectional view of the laser module shown in FIG. 9;

11 is a side cross-sectional view of the laser module of the embodiment of the pattern 3;

12 is a side cross-sectional view of the laser module of the embodiment of the pattern (3),

13 is a side cross-sectional view of the laser module of the embodiment of the pattern (3),

14 is a method of manufacturing a substrate of a semiconductor laser device;

15 is a cross-sectional view for illustrating a layer structure of a semiconductor laser device;

<Description of Symbols for Major Parts of Drawings>

10: CAN package 12: condenser lens

13 optical fiber 19 collimator lens

B, B1-B8: laser beam LD, LD1-LD8: semiconductor laser element

P1: First Package P2: Second Package

The laser module of the present invention has a relative position for coupling one or a plurality of semiconductor laser elements, a condensing optical system, an optical fiber, and a laser beam emitted from the semiconductor laser element to an incident end surface of the optical fiber by the condensing optical system. Fixing means for fixing the semiconductor laser element, the condensing optical system, and the optical fiber, a first package containing the semiconductor laser element and hermetically sealed, and an incidence end protecting the incident end surface of the optical fiber from the atmosphere It is characterized in that the surface protection means is formed.

It is preferable that the said 1st package uses the adhesive which does not contain a flux free solder or Si type organic substance, or is hermetically sealed by fusion or welding.

The first package is preferably filled with an inert gas, and more preferably contains oxygen, a halogen group gas, and / or a halogen compound gas at a concentration of 1 ppm or more. Namely, as the internal atmosphere of the first package, (1) a mixed gas of inert gas and oxygen having a concentration of 1 ppm or more, (2) a mixed gas of at least one of a halogen group gas and a halogen compound gas, (3) It is more preferable that it is any one of a mixed gas of an inert gas, oxygen of 1 ppm or more, and at least one of a halogen group gas and a halogen compound gas.

As the protecting means, a transparent body having at least the other surface opposite to the surface to be fixed to the incident end surface can be used.

As the protection means, a second package different from the first package can be used, which is hermetically sealed by including the incident end face of the optical fiber. At this time, it is preferable that the second package is hermetically sealed by fusion or welding using an adhesive containing no flux-free solder or Si-based organic substance. Alternatively, at least one of the first or second packages may be crimped and hermetically sealed using a resin containing no Si-based organic material.

In addition, it is preferable that the second package is filled with an inert gas in the same manner as the inside of the first package, and oxygen, a halogen group gas, and / or a halogen compound gas in a concentration of 1 ppm or more is mixed in the inert gas. It is more preferable.

When the protection means is a second package, the first package may be contained in the second package, and conversely, the second package may be contained in the first package.

In addition, it is preferable to further include a third package which is hermetically sealed by including the first package, the incident end face of the optical fiber and the incident end face protecting means.

Moreover, this invention is preferable to the laser module whose oscillation wavelength of the said semiconductor laser element is 350 nm-500 nm. Examples of such a semiconductor laser device include those made of GaN-based semiconductors.

The semiconductor laser device includes a plurality of single cavity semiconductor laser devices arranged in an array, one multi cavity semiconductor laser device, a plurality of multi cavity semiconductor laser devices arranged in an array, and a single cavity semiconductor laser device and a multi cavity semiconductor. It is preferable that it is either combination of a laser element.

Here, the first package, the second package, and the third package are not limited to one member each, but may be composed of a plurality of members constituting the airtight sealing space. The first package and the second package may be configured to share one member in part.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail using drawing.

First, the laser module according to the first embodiment of the present invention will be described. 1 is a side view showing a schematic configuration thereof.

The laser module of this embodiment includes a semiconductor laser element LD therein and is hermetically sealed in a CAN package 10, a condenser lens 12, an optical fiber 13, and the optical fiber 13. It is composed of a glass block 15 of a rectangular parallelepiped fused to the incident end surface 14. In the present embodiment, the CAN package 10 is the first package P1, and the glass block 15 fused to the incident end face 14 of the fiber 13 is the incident end face protecting member.

The glass block 15 having the CAN package 10, the condenser lens 12, and the optical fiber 13 is attached to each of the fixing members 5a, 5b, and 5c on the common base plate 5 by the semiconductor laser element LD. Is fixed so as to converge the incident end surface 14 of the optical fiber 13 by the condensing lens 12. In each fixing, an adhesive 7 containing no flux-free solder or Si-based organic substance is used. It may also be fixed by fusion or welding.

The laser beam B emitted from the semiconductor laser device LD is emitted from the glass window of the CAN package 10 to the outside of the CAN package 10, is collected by the condenser lens 12, and the optical fiber through the glass block 15. It enters the core of 13), propagates in the fiber, and exits from the incidence end surface of the optical fiber 13 (not shown).

The CAN package 10 is hermetically sealed after degassing to remove volatile components therein. The incidence end face 14 of the optical fiber 13 is pressed against the glass block 15 and fused. The semiconductor laser element LD is provided in the CAN package 10 degassed and hermetically sealed, and at the time of the degassing process of the CAN package 10, the optical fiber 13 is not disposed in the degassing apparatus. It is not influenced by degassing from the resin film of the optical fiber 13. Therefore, contaminants in the CAN package 10 can be sufficiently reduced, and adhesion of the contaminants to the end face of the semiconductor laser element can be suppressed. In addition, since the incidence end face 14 of the optical fiber 13 is fused to the glass block 15, it is protected from the atmosphere, thereby effectively preventing contaminants from adhering to the incidence end face 14 of the optical fiber 13. Can be.

The condenser lens 12 may be exposed to the outside because the light density does not become very high. However, in order to further improve the reliability of the module, it is preferable to include a hermetically sealed package (third package) P3 covering each member disposed on the base substrate indicated by the dotted line in the figure.

Moreover, in the said embodiment, although the glass block was used as an incident end surface protection member, what is necessary is just a transparent body, and you may use plastic.

In the above embodiment, the glass block 15 is fixed to the incidence end face 14 of the optical fiber 13 by fusion, but as shown in FIG. 2, the periphery near the incidence end face of the optical fiber 13 is shown. Metallization to form the metal layer 16, and furthermore, metallization of the bonding surface of the optical fiber 13 of the glass block 15 to form the metal layer 17, and the solder 18 to the optical fiber 13 and glass The block 15 may be fixed. In addition, in order to increase the beam transmittance, it is preferable to apply an end surface coat having no reflection to the oscillation wavelength of the laser beam in order to increase the beam transmittance.

As shown in Fig. 3, the resin film 13b on the incident end side of the optical fiber 13 is peeled off, a glass ferrule 33 is mounted, and this is pressed onto the glass block 15 so that the optical fiber 13 The entire core of the element wire 13a may be kept in contact with the glass block 15. The tip of the ferrule 33 is preferably polished in a spherical shape. As shown in Fig. 3, the receptacle 30, which is a holding member for fitting with the ferrule 33 and holding the ferrule 33, is fixed to the glass block 15 by solder 18, and What is necessary is just to provide the connector 31 provided with the spring 32 which fits into the receptacle 30, and presses the ferrule 22 to a glass surface. In this case, since the optical fiber 13 can be separated and handled, the handleability of the laser module is improved.

In either case, the module of the optical fiber 13 is mounted after the incident end of the optical fiber 13 is protected.

The first embodiment uses a transparent body fixed to the incidence end face 14 as a protective member for protecting the incidence end face 14 of the optical fiber 13. Hereinafter, the incidence end face ( An embodiment provided with a second package P2 containing 14) will be described.

The semiconductor laser module of the second embodiment of the present invention basically includes a semiconductor laser element LD, a condensing optical system, an optical fiber 13, a fixing member for holding and fixing them in a predetermined positional relationship, and a semiconductor laser element. A first package P1 containing LD and hermetically sealed, and a second package P2 hermetically sealed by containing the incident end surface 14 of the optical fiber 13 are provided. The present embodiment largely depends on what the first package P1 and the second package P2 contain other than the incidence end surface of the semiconductor laser element LD and the optical fiber, and what does not contain. It can be classified into eight patterns. The schematic diagram is shown and demonstrated in each pattern (1)-(8) in FIG.

In FIG. 4, LD represents a semiconductor laser element, F represents an optical fiber, and L represents an optical component including a condensing optical system. In addition, although each package is equipped with the light incidence window or the light emission window member (sealing window member) which is not shown in figure, an optical component may also serve as a window member. An optical component consists of one or more elements. It is common that the first package P1 contains the semiconductor laser element LD, and the second package P2 contains the incident end surface 14 of the optical fiber 13 and is hermetically sealed, respectively. Only features and differences will be described with respect to the pattern of.

In the pattern 1, the first package P1 and the second package P2 are completely sealed independently, and the optical component L is not contained in either package.

In the pattern (2), the second package P2 contains at least a part of the optical component (L).

In the pattern 3, the second package P2 contains at least a part of the first package P1 and the optical component L. As shown in FIG.

In the pattern 4, the first package P1 contains at least a part of the optical component L. As shown in FIG.

In the pattern 5, the 1st package P1 and the 2nd package P2 contain a part of optical component L, respectively.

In the pattern 6, the first package P1 contains at least a part of the optical component L, and the second package P2 contains at least a part of the first package P1 and the optical component L. will be.

In the pattern 7, the first package P1 contains at least a part of the optical component L and the second package P2.

In the pattern 8, the second package P2 contains at least a part of the optical component L, and the first package P1 contains at least a part of the second package P2 and the optical component L. will be.

In addition, as in the patterns (3), (6), (7), and (8), the fact that one package includes at least a part of the other package may include a part of the other package and be sealed. For example, the pattern (3) includes the same thing as (a)-(c) shown by the schematic diagram in FIG. That is, as shown in FIG. 5A, not only the second package P2 includes all of the first packages P1, but also the second package P2 as shown in FIG. 5B. A part of the first package P1 is sealed by the first package P1, and as shown in FIG. 5C, the second package P2 is a sealing window of the first package P1. It also includes the state sealed by the glass part (W).

In any of the patterns (1) to (8), the third package P3 further containing the first package P1 and the second package P2 may be provided. By providing the 3rd package P3, the dust collection effect to the part with high optical density can be suppressed further, and the reliability of a laser module can be improved.

6 is a side cross-sectional view of an embodiment of a specific laser module of the above-described pattern (1). 7 is a partially enlarged cross-sectional view of the second package of this laser module. The laser module collimates to parallelize the CAN package 10, which is the first package P1, which is hermetically sealed by containing the semiconductor laser element LD, and the laser beam B emitted from the CAN package 10. Each of the housings 38 includes a lens 19, a condenser lens 12, an optical fiber 13, and a second package P2 that is hermetically sealed by containing the incident end surface 14 of the optical fiber 13. It is made by being fixed to the fixing member. Further, the laser beam B emitted from the semiconductor laser element LD is carefully arranged and fixed so as to converge on the incident end surface 14 of the optical fiber 13 by the condensing lens 12. In addition, the adhesive 7 which does not contain a flux-free solder or Si type organic substance is used for each fixation. It may also be fixed by fusion or welding.

The laser beam B emitted from the semiconductor laser device LD is emitted from the glass window of the CAN package 10 to the outside of the CAN package 10, is collected by the condenser lens 12, and enters the core of the optical fiber 13. It propagates inside the fiber 13 and exits from the exit end face of the optical fiber 13 (not shown).

The CAN package 10 is hermetically sealed after degassing to remove volatile components therein. The semiconductor laser element LD is provided in the CAN package 10 which is degassed and hermetically sealed, and at the time of the degassing process of the CAN package 10, the optical fiber 13 is not disposed in the degassing apparatus. It is not influenced by the degassing from the resin film 13b of the optical fiber 13. Therefore, contaminants in the CAN package can be sufficiently reduced to suppress adhesion of contaminants to the end face of the semiconductor laser device.

The second package P2 is composed of a ferrule holding part 37 having a cylindrical ferrule holding part, and a glass plate 35 provided on the side facing the ferrule 33 of the glass ferrule 33 and the ferrule holding part 37. It is.

Sealing of the 2nd package P2 is performed as follows. After removing the resin film in the vicinity of the incidence end face 14 of the optical fiber 13, the resin film is passed through a thin hole in the center of the ferrule 33, and fused and sealed to the ferrule 33. The so-called metallization is performed around the ferrule 33 by vapor deposition or plating, and the end face of the ferrule 33 that has passed through the fiber strand 13a is polished and processed into a spherical surface or a plane, and then the deposition is performed. AR coating is performed. In addition, during AR coating, a jig for cooling the fiber coating is used so that the high temperature state of the fiber end surface during deposition is not transmitted to the coating. The ferrule holding part 37 is plated on its entire surface and subjected to degassing treatment. The ferrule 33 is hermetically fixed to the holding part 37 by the flux-free solder 39. In addition, the glass plate 35 which performed AR coating on both surfaces is similarly sealed and fixed with flux-free solder. The inside of the seal is preferably clean air. In addition, nitrogen and an inert gas may be sufficient. As a result, the incidence end face 14 of the optical fiber 13 is protected from the atmosphere, and adhesion of contaminants to the incidence end face 14 of the optical fiber 13 can be effectively prevented.

In the present embodiment, the second package P2 covers the CAN package 10, the collimator lens 19, and the condenser lens 12, and has an opening on the wall, so that the second package P2 has its ferrule holding part ( Solder is fixed at the part 37). The housing 38 does not necessarily have to be hermetically sealed, but by hermetically sealing the dust collecting effect is more effectively suppressed.

Next, the laser module which is embodiment of the pattern 5 is demonstrated. 8 is a side sectional view showing a schematic configuration of this laser module.

In this laser module, the semiconductor laser element LD and the collimator lens are accommodated in the CAN package 10, and the CAN package 10, the condenser lens 12, and the incident end surface 14 of the optical fiber 13 are It is contained in one package 60. The fixing part 66 holding the condensing lens 12 is formed in the shape of a cylindrical portion accommodating the condensing lens 12, and the condensing lens 12 contains flux-free solder or Si-based organic material. It is fixed by the adhesive agent 7 which does not.

The condenser lens 12 has a function of separating the inside of the package 60 into two spaces. That is, the package 60 is composed of the first package portion P1 containing the CAN package 10 and the second package portion P2 containing the incident end surface 14 of the optical fiber 13 integrally. Can be considered. The optical fiber 13 is inserted into a hole formed in the wall surface of the second package portion P2 of the package 60 and sealed by flux-free solder 39. In this laser module, even if the semiconductor laser element LD and the collimator lens 19 are not contained in the CAN package 10, they are contained in the first package portion P1, so that the effect of preventing dust collection can be sufficiently obtained. However, by providing the CAN package 10, dust collection prevention is more effective.

Next, the laser module which is embodiment of the pattern 7 is demonstrated. 9 and 10 are a plan view and a side view showing a schematic configuration of this laser module.

As shown in Figs. 9 and 10, the laser module according to the present embodiment is an example in which eight GaN semiconductor laser elements LD1 to 8 are arranged and fixed on a heat block (heat dissipation block) 50 made of copper or copper alloy. LD8), collimator lens array 46, and condenser lens 12 are housed in package 40, which is the first package P1 having light exit aperture 36, to cover light exit aperture 36. Then, the second package P2, which is hermetically sealed by containing the optical fiber 13, is fixed to the first package 40.

6 and 7, the second package P2 has a configuration as shown in Figs. 6 and 7, and has a ferrule holding part 37 having a cylindrical ferrule holding part, and a ferrule 33 of a glass ferrule 33 and a ferrule holding part 37. It is comprised by the glass plate 35 provided in the side opposite to). The 2nd package P2 is fixed to the 1st package 40 so that the light output opening 36 may be sealed by the glass plate 35 of this 2nd package P2. That is, the glass plate 35 is not only a light incident window member of the second package P2, but also a light exit member of the first package P1.

9 and 10 show a basic configuration of the laser module of this embodiment, and the shapes of the collimator lens array 11 and the condenser lens 12 are schematically shown. In addition, in order to avoid the trouble of drawing, the code | symbol is attached only to the elements LD1 and LD8 arrange | positioned at both ends of a GaN type semiconductor laser element, and only the code | symbol is attached only to B1 and B8 among the laser beams B1-B8. The GaN semiconductor laser elements LD1 to LD8 may be attached to a heat block, for example, fixed on a submount made of AlN.

The laser beams B1 to B8 emitted in the divergent light state from the GaN semiconductor laser elements LD1 to LD8 are parallelized by the lens array 46, respectively. The laser beams B1 to B8 made of parallel light are collected by the condensing lens 12 and converged at the incident end surface 14 of the optical fiber 13.

In this example, the condensing optical system is constituted by the lens array 11 and the condenser lens 12, and the combined optical system is constituted by the optical fiber 13 and it. That is, the laser beams B1 to B8 condensed as described above by the condenser lens 12 are incident on the core of the optical fiber 13 to propagate in the optical fiber 13, and to one laser beam B. It is combined and emitted from the exit end face of the optical fiber 13 (not shown).

The base plate 42 is fixed to the bottom surface of the package 40, and a heat block 10 is attached to the top surface of the base plate 42, and the lens array 11 is held on the heat block 10. The collimator lens holder 44 is fixed. The condenser lens holder 45 holding the condenser lens 12 is fixed to the upper surface of the base plate 42. The wirings 47 for supplying a driving current to the GaN semiconductor laser elements LD1 to LD8 pass through an opening formed in a horizontal wall surface facing the wall surface on which the light exit window 16 of the package 40 is formed. It is drawn out.

In the laser module of the present embodiment, since the laser beams B1 to B8 emitted from the plurality of semiconductor laser elements LD1 to LD8 converge on the incident end surface of the optical fiber 13, the incident end of the optical fiber 13 Surface light density becomes very high. As in the present embodiment, since the incident end surface 14 of the optical fiber 13 is hermetically sealed in the second package to be protected from the atmosphere, the effect of suppressing dust collection to the incident end surface 14 is large.

In this embodiment, eight semiconductor laser devices LD1 to LD8 of a single cavity are provided, but for example, a chip having a multi cavity such as four semiconductor laser devices of two cavities may be provided. In addition, you may provide the semiconductor laser bar 1 element which has an 8 cavity. In addition, it is not limited to a GaN type semiconductor laser element.

11 is a side cross-sectional view of an embodiment of a specific laser module of the pattern (3). The laser module includes the CAN package 10 containing the semiconductor laser element LD which is the first package P1, the incident end surface 14 of the optical fiber 13, and the condenser lens 12 and A second package P2 for accommodating the CAN package 10 is provided. Both the CAN package 10 and the second package are hermetically sealed, and therefore, the semiconductor laser element LD is in a double sealed state. Since the end face of the semiconductor laser element is particularly high in light density and high in dust collection effect, such double sealing is more effective in suppressing the dust collection effect. In the case of the pattern 6, the second package P2 has the same effect as if the second package P2 completely contains the first package P1.

In addition, in the case of the pattern 7 and the pattern 8, the structure in which the 2nd package P2 which contains the optical fiber incidence end surface is completely contained in the 1st package is equipped with especially a some semiconductor laser element, It is effective to apply the light emitted from the plurality of semiconductor laser elements to a laser module of a combined wave type that combines one optical fiber. The incidence end face of the optical fiber to which the laser beams emitted from the plurality of semiconductor laser elements is combined may increase the optical density beyond the end face of each semiconductor laser element, and also increase the dust collection effect. Therefore, in the combined wave type laser module, a structure for double sealing the incident end surface of the optical fiber is suitable.

12 and 13 show embodiments of another laser module of the pattern (3). Each laser module includes a CAN package 10, a condenser lens 12, and an optical fiber 13, and a CAN package 10 and a condenser lens 12 in which the second package P2 is the first package. ) And the incident end face 14 of the optical fiber 13 are hermetically sealed.

In FIG. 12, the second package P2 has a cylindrical body 21 accommodating the CAN package 10 and the condenser lens 12, and is screwed on the cylindrical body 21 via an O-ring 23. It consists of the cover body 22 which comprises the crimp sealing structure which used the O-ring 23 by this. The optical fiber 13 is inserted into a hole formed in the cover body 22 and sealed. Meanwhile, in FIG. 13, the second package P2 has a sealing structure by the metal sleeve 25, and at the same time holds the metal sleeve 25 and the CAN package 10 having the screw grooves on the inner circumference thereof. It consists of the holding body 26 which has a flange with the surface 26a which contacts the part 25a of the sleeve 25, and the cylindrical body 27 which accommodates the condensing lens 12, The metal sleeve 25 By contacting a portion 25a of the flange to the contact surface 26a of the flange and screwing the cylindrical body 27, the cylindrical body 27 is press-fitted to the holding body 26 side, and at both slope portions 27b and 26b. The space is sealed. In addition, the optical fiber 13 is inserted into the hole formed in the bottom of the cylindrical body 27, and it is sealed and fixed.

12 and 13, when the second package P2 has a screw structure using an O-ring and a metal sleeve, a decrease in transmittance due to failure of the semiconductor laser element LD, contamination of the optical fiber 13, or the like can be obtained. Even if it exists, there is an advantage that it can be replaced easily. However, compared with the sealing structure by welding, solder, adhesive, etc., there exists a disadvantage that the sealing reliability is inferior and the fiber part deteriorates quickly by contamination. In addition, it is preferable to use what does not contain Si type organic substance as an O ring, and it is especially preferable to use a fluororesin.

In each of the embodiments, the gas to be filled in the first package, the second package, and the third package is preferably composed of an inert gas. Nitrogen, a rare gas, etc. are mentioned as an inert gas. Moreover, the mixed gas of an inert gas and at least 1 type of oxygen, halogen group gas, and halogen compound gas of 1 ppm or more concentration may be sufficient, For example, using clean air which is nitrogen and oxygen mixed gas of the same ratio as air | atmosphere, Also good.

When oxygen of 1 ppm or more is contained in a sealing atmosphere, deterioration of a laser module can be suppressed more effectively. This deterioration suppression effect can be improved because oxygen contained in the sealing atmosphere oxidatively decomposes a solid produced by photolysis of the hydrocarbon component.

Halogenated gas is halogen gas such as chlorine gas (Cl ₂ ) or fluorine gas (F ₂ ), and halogen compound gas is chlorine atom (Cl), bromine atom (Br), iodine atom (I), fluorine atom (F) It is a gaseous compound containing halogen atoms, such as).

As the halogen compound gas, CF ₃ Cl, CF ₂ Cl ₂ , CFCl ₃ , CF ₃ Br, CCl ₄ , CCl ₄ -O ₂ , C ₂ F ₄ Cl ₂ , Cl-H ₂ , CF ₃ Br, PCl ₃ , CF ₄ , SF ₆ , NF ₃ , XeF ₂ , C ₃ F ₈ , CHF ₃ and the like, but compounds of fluorine or chlorine with carbon (C), nitrogen (N), sulfur (S), and xenon (Xe) are preferred. It is particularly preferable to contain fluorine atoms.

The halogen-based gas exhibits a deterioration suppression effect even in a small amount, but in order to obtain a significant deterioration suppression effect, it is preferable to make the content of halogen-based gas be 1 ppm or more. This deterioration suppression effect is obtained because the halogen gas contained in the sealing atmosphere decomposes the deposits generated by photolysis of the organosilicon compound gas.

Moreover, although the form of fixing of a semiconductor laser element, a condensing optical system, and an optical fiber in an inside of a package, and sealing of a package was given, the example which used the flux-free solder or the adhesive which does not contain Si-type organic substance was mentioned, It is preferable to perform sealing by the adhesive which does not contain a flux-free solder or Si organic substance, or fusion | melting or welding.

As an adhesive which does not contain Si-type organic substance, it is an adhesive composition containing the alicyclic epoxy compound of Unexamined-Japanese-Patent No. 2001-177166, the compound which has an oxetanyl group, and a catalytic amount of onium salt photoreaction initiator, for example. And those made of an adhesive composition containing no silane coupling agent.

Moreover, as flux-free solder, Sn-Pb, Sn-In, Sn-Pb-In, Au-Sn, Ag-Sn, Sn-Ag-In etc. are mentioned, for example. Flux contained in a conventional solder material causes contamination, but there is no fear of generating pollutants when using flux-free solder. In addition, it is preferable to use lead-free solder in consideration of the environment.

Welding can be performed using a commercially available seam welder, for example, a seam welder manufactured by Nippon Avionics. Specifically, the package can be welded and sealed by placing a cover on the package and applying a high voltage to the boundary between the cover of the package and the housing by a seam welder. In addition, fusion | melting can be performed using a commercially available fusion machine, for example, FITEL S-2000.

Next, the manufacturing method of a GaN type semiconductor laser element is demonstrated as an example of the semiconductor laser element used in the said embodiment. 14 is a cross-sectional view showing a step of manufacturing a GaN semiconductor laser device.

As shown in Fig. 14A, trimethylgallium (TMG) and ammonia are used as growth materials by organometallic vapor phase growth, silane gas is used as the n-type dopant gas, and cyclopenta is used as the p-type dopant. Using dienyl magnesium (Cp ₂ Mg), a GaN buffer layer 122 is formed on the (0001) C surface sapphire substrate 121 at a temperature of 500 ° C. with a film thickness of about 20 nm. Subsequently, the GaN layer 123 is grown to about 2 mu m at a temperature of 1050 占 폚. Thereafter, the SiO ₂ film 124 is formed, the resist 125 is applied, and then using conventional lithography,

By removing the SiO ₂ film 124 having a width of 3 μm in the direction and forming the line portion of the SiO ₂ film 124 having a width of about 7 μm, a line and space pattern having a cycle of about 10 μm is formed.

Next, as shown in Fig. 14B, the resist layer 125 and the SiO ₂ film 124 are used as masks, and the buffer layer 122 and the GaN layer 123 are subjected to dry etching using a chlorine-based gas. After removing the sapphire substrate 121 to the upper surface, the resist 125 and the SiO ₂ film 124 are removed. At this time, the sapphire substrate 121 may be slightly etched.

Next, as shown in Fig. 14C, the GaN layer 126 is selectively grown by about 20 mu m. At this time, the stripe finally merges by the growth in the lateral direction, and the surface is flattened. At this point, the through potential is generated in the upper portion of the line portion of the layer composed of the buffer layer 122 and the GaN layer 123, but the through potential is not generated in the GaN layer 126 between the line portions.

Subsequently, a SiO ₂ film 127 is formed on the GaN layer 126, and as shown in FIG. 14 (d), the space portion between the line portion formed by the buffer layer 122 and the GaN layer 123 remains. The SiO ₂ film 127 located at the center is removed by about 3 m.

Next, as shown in Fig. 14E, the GaN layer 128 is selectively grown by about 20 mu m at a growth temperature of 1050 占 폚. At this time, the stripe is finally merged by the growth in the lateral direction, and the surface is flattened.

Then, a, SiO ₂ film 129, which is located in the center of the remaining SiO ₂ film 127 as shown in (f) of the SiO ₂ film 129 in the formation, and 14 on the GaN layer 128 width 3 micrometers is removed and the GaN layer 130 is selectively grown by 20 micrometers on the growth temperature of 1050 degreeC.

Finally, as shown in Fig. 14G, the n-GaN layer 131 is grown to about 100 to 200 mu m on the GaN substrate fabricated as described above, and then the sapphire substrate to the GaN layer 130 is grown. Is removed to make the n-GaN layer 131 an n-type GaN substrate 141 shown in FIG. 15 is a partial cross-sectional view of the wafer before cleavage for explaining the layer structure of the semiconductor laser device.

Next, as shown in FIG. 15, on the n-type GaN substrate 141 prepared as described above, the n-GaN buffer layer 142 and 150 pairs of n-Al _0.14 Ga _0.86 N (2.5 nm) / GaN (2.5 nm) superlattice cladding layer 143, n-GaN optical waveguide layer 144, n-In _0.02 Ga _0.98 N (10.5 nm) / n-In _0.15 Ga _0.85 N (3.5 nm) triple quantum well active layer (145) ), p-Al _0.2 Ga _0.8 N carrier block layer 146, p-GaN optical waveguide layer 147, 150 pairs of p-Al _0.14 Ga _0.86 N (2.5 nm) / GaN (2.5 nm) superlattice cladding layer ( 148, p-GaN contact layer 149 is laminated. Here, Mg is used as a p-type impurity. In order to activate the Mg, either a heat treatment may be performed in a nitrogen atmosphere after growth, or growth may be performed in a nitrogen rich atmosphere.

Next, when fabricating a lateral single mode semiconductor laser, the SiO ₂ mask 150 having a stripe-shaped opening having a width of 1 to 3 µm is formed to have a pitch of 100 to 500 µm in order to form a stripe region in which the lateral mode becomes single. In the case of producing a lateral multimode blob semiconductor laser, a SiO ₂ mask 150 having a stripe-shaped opening having a width in the range of 50 µm to 50 µm is formed at a pitch of 100 to 500 µm. An output of about several hundreds to 2000 microseconds is obtained from a lateral multimode blob semiconductor laser having a stripe region of several to 50 mu m in width.

Next, the stripe-shaped p-electrode 151 made of Ni / Au is formed so as to cover the stripe-shaped opening. Subsequently, the substrate 141 is polished to form an n-electrode 152 made of Ti / Au, and a high reflection coat and a low reflection coat are applied to the resonator surface formed by cleaving. The semiconductor laser element LD having a cavity and a resonator length is completed.

In the case of a multi-cavity semiconductor laser element, the resonator length is 100 to 1500 µm, preferably 400 µm, and is cleaved so that the length of the light emitting point array direction is 1 cm, for example, and high reflection and low reflection on the cavity surface are achieved. Coating is performed, for example, and the bar-shaped element which has 20 cavities is completed. In the case of forming a multi-cavity, the device is formed by cleaving the element width in the light emitting point array direction in accordance with the required number of cavities.

When forming a single cavity semiconductor laser element, it cleaves at 100-500 micrometer pitch equivalent to the formation pitch of stripe area | region, and is set as the element of 400 micrometers resonator length which has a single cavity.

Since the laser beam having a wavelength of 500 nm or less output from such a GaN semiconductor laser is high energy, the optical density is very high at the laser end face or the incident end face of the optical fiber, and hence the dust collection effect is also high. Therefore, in the laser module provided with the semiconductor laser element for generating such a high energy laser beam, as in the present invention, it is possible to effectively suppress dust collection by having a structure in which the semiconductor laser element and the incident end face are respectively protected from the atmosphere. It is preferable to be able.

In the laser module according to the present invention, the semiconductor laser device accommodated in the package includes a single-cavity semiconductor laser device (LD bar) in which the discrete single cavity chips shown in the above embodiments are arranged in an array. Or a plurality of multi cavity semiconductor laser elements arranged in an array, or a combination of a single cavity semiconductor laser element and a multi cavity semiconductor laser element.

The laser module of the present invention includes a first package formed by hermetically sealing a semiconductor laser element and an incident end surface protection means for protecting the incident end surface of the optical fiber from the atmosphere. Since the optical fiber is not attached at the time of the degassing treatment and hermetic sealing of the first package, no contamination by degassing from the resin film of the optical fiber occurs in the first package. Therefore, dust collection to the end surface of the semiconductor laser element with high light density and high dust collection effect can be suppressed. In addition, since the incident end surface protection means is formed on the incident end surface of the optical fiber having a high optical density, dust collection can be prevented and a highly reliable laser module can be provided.

The first package for protecting the semiconductor laser element and the incidence end protection means for protecting the incidence end face of the optical fiber are separately formed on the end face, the end face of the optical fiber, or both of them, where the optical density is particularly high. The influence of the adhesive used for fixing the optical member or the volatile contaminants mixed in the module manufacturing process can be made smaller, and the reliability of the entire module can be improved. In addition, if the countermeasure against contamination of the site where the light density becomes high is carried out in advance, the reliability improvement measures such as degassing treatment etc. can be omitted for the site where the light density is low, and the manufacturing process of the entire module can be simplified.

As described above, the contamination effect (dust collecting effect) is more likely to occur as the light density is higher. In the pigtail type module, in general, the semiconductor laser device output end has the highest optical density, and then the optical fiber incidence end becomes high. The light emitted from the semiconductor laser device has a large spreading characteristic. Therefore, in a semiconductor laser device, as shown by a so-called CAN package, a semiconductor laser device is constructed in which a high clean density is maintained and a semiconductor laser device end surface having high optical density is protected between a predetermined distance from the semiconductor laser device end surface. The contamination effect is unlikely to occur because the laser light is emitted from the CAN package window surface from which the laser beam is emitted from the outside. Incident light to the fiber is also focused and radiated light. Therefore, similarly, if a high cleanliness is maintained within the predetermined distance from the end surface and protected from the atmosphere, the light density of the boundary surface radiated from the protection portion is suppressed to be low and the pollution effect is lowered.

As a protective means for protecting the incidence end face of the optical fiber, when a transparent body having at least the other face opposite to the incidence face which is fixed to the incidence end face is used, the incidence end face of the optical fiber can be effectively removed from the atmosphere. I can protect it.

In addition, when a second package different from the first package, which is formed by sealing the incidence end face of the optical fiber and is hermetically sealed by including the incidence end face of the optical fiber, the incidence end face of the optical fiber is used. Effective protection from the atmosphere.

If the first package, the second package, or both packages are sealed using a flux-free solder or an adhesive containing no Si-based organic matter, or hermetically sealed by fusion or welding, it is possible to suppress the generation of volatile components that cause contamination. It can suppress the adhesion of contaminants.

Further, if the first package, the third package formed by hermetically sealed by including the incident end surface and the incident end surface protection means of the optical fiber, further contaminants adhere to the incident end surface of the semiconductor laser element and the optical fiber. It can reduce and is effective.

Moreover, especially when a semiconductor laser element emits the wavelength of 350 nm-500 nm, since energy becomes high and dust collection effect becomes large, applying this invention is effective in preventing adhesion of a contaminant. In addition, in the laser module which combines a plurality of laser beams from a plurality of semiconductor laser elements or a multi-cavity semiconductor laser element into one fiber, the light intensity on the fiber end surface becomes very high, so that the effect of applying the present invention is very high. high.

Claims (15)

One or a plurality of semiconductor laser elements; Condensing optical system; Optical fiber; Fixing means for fixing the semiconductor laser element, the condensing optical system, and the optical fiber at a relative position to couple the laser beam emitted from the semiconductor laser element to the incident end surface of the optical fiber by the condensing optical system; A first package containing the semiconductor laser element and hermetically sealed; And And an incident end surface protection means for protecting the incident end surface of the optical fiber from the atmosphere. The laser module according to claim 1, wherein the first package is hermetically sealed by fusion or welding by using an adhesive containing no flux-free solder or Si-based organic matter. The laser module according to claim 1 or 2, wherein the first package is filled with an inert gas. The laser module according to claim 3, wherein oxygen, a halogen group gas, and / or a halogen compound gas at a concentration of 1 ppm or more is mixed in the inert gas. The laser module according to any one of claims 1 to 4, wherein the protection means is a transparent body having a surface opposite to at least the surface to be fixed, which is fixed to the incident end surface. The laser according to any one of claims 1 to 4, wherein the protective means is a second package different from the first package, which is formed by sealing an incidence end face of the optical fiber and hermetically sealed. module. The laser module according to claim 6, wherein the second package is hermetically sealed by fusion or welding using an adhesive containing no flux-free solder or Si-based organic matter. 7. The laser module according to claim 6, wherein at least one of the first and second packages is crimped and hermetically sealed using a resin containing no Si-based organic material. The laser module according to any one of claims 6 to 8, wherein the second package is filled with an inert gas. 10. The laser module according to claim 9, wherein oxygen, a halogen group gas, and / or a halogen compound gas at a concentration of 1 ppm or more is mixed in the inert gas. The laser module according to any one of claims 6 to 10, wherein the first package is contained in the second package. The laser module according to any one of claims 6 to 10, wherein the second package is contained in the first package. 13. The package according to any one of claims 1 to 12, further comprising a third package which is hermetically sealed by including the first package, the incident end surface of the optical fiber, and the incident end surface protection means. Laser module. The laser module according to any one of claims 1 to 13, wherein the oscillation wavelength of the semiconductor laser device is 350 nm to 500 nm. The semiconductor laser device according to any one of claims 1 to 14, wherein the semiconductor laser device includes a plurality of single cavity semiconductor laser devices arranged in an array, one multi cavity semiconductor laser device, and a plurality of multi cavities arranged in an array. And a combination of a single cavity semiconductor laser element and a multi cavity semiconductor laser element.