JP2004252425A - Laser module and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high output and high reliability at a low cost in a laser module comprising semiconductor laser elements, optical fibers, and a converging optical system for converging laser beams emitted from the semiconductor laser elements and coupling the beams to the incident end of an optical fiber. <P>SOLUTION: Eight pieces of GaN semiconductor laser elements LD1 to LD8 fixedly aligned on a heat block (heat-sink block) 10, collimator lenses 11, and a condenser lens 12 are fixedly arranged in a package 40 having a light exiting window 16 covered with a light transmission member 15 on the wall surface. In the state that the laser elements LD1 to LD8, collimator lens 11, and the condenser lens 12 are arranged and fixed so that the laser beams emitted from the laser elements LD1 to LD8 are converged on the outside surface 15a of the light transmission member 15, the inside of the package 40 is degassed and hermetically sealed, and thereafter, the incident end of the optical fiber 13 is pressed into close contact with the light exiting window 15 for fixing. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a laser module and a manufacturing method thereof, and in particular, a laser module including 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 face of the optical fiber, and It relates to the manufacturing method.

  Conventionally, a semiconductor laser element housed in a package, an optical fiber fixed to the package with one end (light incident end) facing the inside of the package, and a laser beam emitted from the semiconductor laser element A laser module including a condensing optical system coupled to a light incident end of an optical fiber is generally known as an optical communication component as a so-called pigtail laser module.

  Inside the laser module, in order to stably maintain the optically coupled state of the semiconductor laser and the light incident end of the optical fiber on the order of micrometers, the optical fiber and the focusing optical system are usually soldered. It is fixed using an adhesive means such as welding or an adhesive.

  In addition, in a communication laser module, in order to prevent laser deterioration due to moisture in the outside air, the structure typically represented by a so-called CAN package, in which the package is hermetically sealed, includes a semiconductor laser element, and It is representative as a sealing structure for protecting the laser end face. 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 of adhering substances (dust collection effect) in a portion having a high light density is remarkable. Furthermore, in a laser module including a semiconductor laser element that emits a laser beam having a wavelength of 350 to 500 nm (400 nm band), such as a GaN-based semiconductor laser element, the photon energy is high and a photochemical reaction with a substance is more likely to occur. Therefore, the dust collection effect appears more prominently.

  As one of the pollutants, hydrocarbon compounds mixed in from the atmosphere of the manufacturing process can be cited, and this hydrocarbon is polymerized or decomposed by laser light, and decomposed substances adhere to it, preventing improvement in output. Are known.

  In addition, it is disclosed that low molecular weight siloxane floating in the air reacts with oxygen by photochemical reaction by ultraviolet rays, and deposits and adheres to optical glass window parts in the form of SiOx. It is recommended to replace the member regularly (see, for example, Patent Document 1).

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

  In an optical system that irradiates an optical component with ultraviolet rays of 400 nm or less, it has been proposed that the atmosphere of the optical component is 99.9% or more of nitrogen (see, for example, Patent Document 3).

Furthermore, it is also known that performing deaeration inside the package immediately before sealing the package is effective in preventing the dust collection effect.
Japanese Patent Laid-Open No. 11-54852 US Patent 5392305 Japanese Patent Laid-Open No. 11-167132

  However, in the case of a laser module in which an optical fiber is fixed to a package, which is provided with an optical fiber having a primary coating made of UV curable resin and a secondary coating made of a polymer that are generally commercially available, the optical fiber is fixed to the package. Since the degassing process is performed in the wet state, a fiber coating is present in the degassing device, and a degassing component is generated from the coating during the degassing process. become.

  In order to prevent this contamination, it is conceivable to remove all the coating of the optical fiber in advance. However, since the optical fiber without the coating is easily broken, it is difficult to handle and is not practical.

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

The laser module of the present invention includes a hermetically sealed package including a light transmitting member in a light exit window,
One or more semiconductor laser elements disposed inside the package;
An optical fiber disposed outside the package;
A condensing optical system disposed inside the package for condensing a laser beam emitted from the semiconductor laser element on an outer surface of the light transmitting member;
The incident end of the optical fiber is fixed in close contact with a position on the outer surface of the light transmitting member where the laser beam is condensed.

  In addition, it is desirable that a marker for determining a position for condensing the laser beam is attached to the light transmitting member. The light transmitting member may be any member that can transmit the laser beam, and may have any shape such as a circular flat plate, a parallel flat plate, a lens, and a wedge shape.

  Here, the term “closely fixed” includes a state in which it is closely attached and adhered and fixed, and a state in which it is detachably adhered and held and fixed.

  The present invention is suitable for a laser module in which the oscillation wavelength of the semiconductor laser element is 350 nm to 500 nm. Specifically, those composed of GaN-based semiconductors can be mentioned.

  The incident end of the optical fiber may be inserted into a ferrule, and the package may include a mounting device that fits the ferrule.

  The package is preferably filled with an inert gas, and the inert gas contains oxygen, a halogen group gas, and / or a halogen compound gas at a concentration of 1 ppm or more. Is more desirable. That is, the internal atmosphere of the first package includes (1) a mixed gas of an inert gas and oxygen having a concentration of 1 ppm or more, and (2) at least one of an inert gas, a halogen group gas, and a halogen compound gas. (3) A mixed gas of an inert gas, oxygen gas with a concentration of 1 ppm or more, and at least one of a halogen group gas and a halogen compound gas is more preferable.

  The package is preferably hermetically sealed using flux-free solder or an adhesive that does not contain Si-based organic materials, or by fusion or welding.

  The semiconductor laser elements include a plurality of single cavity semiconductor laser elements arranged in an array, a multicavity semiconductor laser element, a plurality of multicavity semiconductor laser elements arranged in an array, and a single cavity semiconductor laser element and a multicavity. It is desirable to be one of the combinations with the cavity semiconductor laser element.

The method for manufacturing a laser module of the present invention includes one or a plurality of semiconductor laser elements, an optical fiber, and a condensing optical system that condenses a laser beam emitted from the semiconductor laser element and couples it to the incident end of the optical fiber. In a method for manufacturing a laser module comprising a system,
The semiconductor laser element and the condensing optical system are disposed in a hermetically sealable package having a light exit window provided with a light transmitting member through which the laser beam is transmitted on one wall surface, and the laser beam transmits the light. Place it so that it is focused on the outer surface of the member,
Degassing the inside of the package;
After the deaeration treatment, the package is hermetically sealed,
Then, the incident end of the optical fiber is fixed in close contact with the outer surface of the light transmitting member so that the laser beam is optically coupled to the incident end of the optical fiber.

  According to the laser module of the present invention, the semiconductor laser element and the condensing optical system are provided and sealed in one package, and the optical fiber is fixed to the outside of the package. This can be done prior to installation and does not cause contamination in the package due to degassing from the optical fiber coating. Further, since the optical fiber and the window are brought into close contact with each other, the light incident end face of the optical fiber does not come into contact with the atmosphere, and contamination can be prevented from adhering to the incident end face of the optical fiber. Further, since the laser beam is focused on the outer surface of the light transmissive member, the light density on the inner surface of the light transmissive member can be suppressed, and even when contaminants remain in the package of the member. Since the ability to decompose organic substances in the vicinity of the inner surface of the light transmitting member can be suppressed, it is possible to suppress the adhesion of contaminants to the inner surface. That is, according to the laser module of the present invention, the adhesion of contaminants, that is, the dust collection effect can be suppressed, so that the light output can be improved and high reliability can be obtained.

  If the light transmitting member is provided with a marker for determining the position to focus the laser beam, the laser beam can be aligned using the marker as a reference while observing the marker with a CCD camera, etc., making alignment easy become. Also, automatic alignment is possible.

  In particular, when the semiconductor laser element emits a wavelength of 350 nm to 500 nm, the energy is increased and the dust collection effect is increased. Therefore, the application of the present invention is to prevent adhesion of contaminants. It is effective. In addition, in a laser module that combines a plurality of laser beams from a plurality of semiconductor laser elements or multi-cavity semiconductor laser elements into a single fiber, the light intensity on the fiber end face becomes very high, so that contaminants The effect of preventing adhesion is remarkable.

  If the incident end of the optical fiber is inserted into the ferrule and the package includes a mounting device that fits with the ferrule, the optical fiber can be easily mounted and the handling property is improved.

  In the method for manufacturing a laser module according to the present invention, the deaeration inside the package is performed before the optical fiber is fixed to the package, so that no contamination from the gas from the coating of the optical fiber occurs. Further, since the optical fiber is finally fixed to the outside of the package, it is not necessary to handle the optical fiber in the process up to the sealing of the package, so that the module can be easily manufactured.

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

  A laser module according to the first embodiment of the present invention will be described. 1 and 2 are a plan view and a side sectional view showing a schematic shape of the laser module. FIGS. 3A and 3B are a partially enlarged side sectional view and a front view of the light exit window 16 and the light transmitting member 15 of the package.

  As shown in FIGS. 1 and 2, the laser module according to the present embodiment includes eight GaN-based semiconductor lasers LD1 to LD8 as an example arranged and fixed on a heat block (heat radiation block) 10 made of copper or a copper alloy. The collimator lens array 11 and the condenser lens 12 are housed in a package 40 having a light exit window 16 provided with a light transmitting member 15, and one optical fiber 13 is disposed outside the package 40. The incident end is pressed against 15 and is fixed in close contact.

  FIGS. 1 and 2 show the basic configuration of the laser module of the present embodiment, and the shapes of the collimator lens array 11 and the condenser lens 12 are schematically shown. In order to avoid complication of the figure, only the elements LD1 and LD8 disposed at both ends of the GaN-based semiconductor laser elements are denoted by reference numerals, and only the B1 and B8 elements of the laser beams B1 to B8 are denoted by reference numerals. It is. The GaN semiconductor lasers LD1 to LD8 may be attached to the heat block 10 by being fixed on a submount made of AlN, for example.

  Laser beams B1 to B8 emitted in a divergent light state from these GaN-based semiconductor laser elements LD1 to LD8 are collimated by the lens array 11, respectively.

  The parallel laser beams B1 to B8 are collected by the condensing lens 12 and aligned so as to converge on the outer surface 15a of the light transmitting member 15 as shown in FIG. The optical fiber 13 has its light incident end inserted into the ferrule 20 and the light transmitting member together with the ferrule 20 so that the light incident end of the optical fiber 13 coincides with the laser beam convergence position on the outer surface 15a of the light transmitting member 15. Adhered to 15. In this example, the lens array 11 and the condensing lens 12 constitute a condensing optical system, and the optical fiber 13 constitutes a multiplexing optical system. That is, the laser beams B1 to B8 collected as described above by the condenser lens 12 enter the core of the optical fiber 13 and propagate through the optical fiber 13, and are combined into one laser beam B. The light is emitted from an output end face (not shown) of the optical fiber 13. The optical fiber 13 is formed by coating an optical fiber strand 13a with a resin layer 13b except for a portion inserted into the ferrule 20.

  As the optical fiber 13, a step index type, a graded index type, and a composite type thereof are all applicable.

  A base plate 42 is fixed to the bottom surface of the package 40, the heat block 10 is attached to the top surface of the base plate 42, and a collimator lens holder 44 for holding the lens array 11 is fixed to the heat block 10. Further, a condenser lens holder 45 that holds the condenser lens 12 is fixed to the upper surface of the base plate 42. Wirings 47 for supplying a drive current to the GaN-based semiconductor laser elements LD1 to LD8 are led out of the package through openings formed in the lateral wall surface of the package 40 facing the wall surface where the light exit window 16 is provided. .

  The light exit window 16 provided in the package 40 is, for example, a φ6 mm round hole, and the light transmitting member 15 provided in the light exit window 16 is a disk-shaped member made of quartz glass or sapphire of φ10 mm. It is attached so as to cover the window 16. The entire surface of the package 40 is gold-plated, and an AR coating is applied to the inner or inner and outer surfaces of the light transmitting member 15. Further, the 1 mm peripheral portion of the light transmitting member 15 is metallized and attached to the package 40 with solder 18. The light transmitting member 15 is not limited to the disk-shaped member, and may have any shape such as a parallel plate, a lens, or a wedge shape.

  FIG. 3B is a front view of the wall surface of the package before fixing the optical fiber 13 as seen from the direction of arrow P in FIG. As shown in FIG. 3B, the light transmission member 15 is provided with a marker 19. The marker 19 is formed on the outer surface 15a of the light transmitting member 15 by etching. The above-mentioned alignment of the laser beam can be performed by using a CCD camera with the marker 19 as a reference.

  Next, a method for manufacturing the laser module of this embodiment will be described.

  With the upper surface of the package 40 open, the light transmitting member 15 is fixed to the wall surface of the package 40 with the solder 18 so as to cover the window 16, and the window 16 is sealed.

  The semiconductor laser elements LD1 to LD8, the collimator lens array 11 and the condenser lens 12 are installed inside the package. At this time, the lens array 11 and the condensing lens 12 are configured to condense the laser beams B1 to B8 emitted from the plurality of semiconductor laser elements LD1 to LD at a predetermined position O on the outer surface 15a of the light transmitting member 15. Then, the CCD camera is used for adjustment with the marker 19 on the outer surface 15a of the light transmitting member 15 as a reference, and is fixed by using flux-free solder or an adhesive that does not contain Si organic materials, or by fusion or welding. The marker 19 may be an aperture whose diameter is equal to or slightly larger than the core diameter of the fiber.

  Note that the lens array 11 and the condenser lens 12 may be aligned before the light transmitting member 15 is attached, and then the light transmitting member 15 may be aligned and fixed to the package 40.

  Thereafter, in order to remove volatile components inside the package, which cause a reduction in long-term reliability of the laser, the package 40 is put into a degassing apparatus and heated to 90 ° C. in a nitrogen atmosphere to perform a degassing process. . The atmosphere gas may be other than nitrogen, for example, oxygen, inert gas, or a mixed gas thereof, or may be decompressed. After the deaeration treatment, a lid 41 is provided on the upper surface of the package 40, and sealing is performed by using flux-free solder or an adhesive that does not contain Si organic materials, or by fusion or welding.

  Thereafter, the incident end of the optical fiber 13 is pressed against and closely adhered to the light transmitting member 15, thereby removing outside air and preventing the incident end of the optical fiber 13 from being contaminated. In this state, fixing is performed by mechanical holding, adhesion, solder fixing, or the like. In order to obtain long-term reliability, fixing is performed by using flux-free solder or an adhesive that does not contain Si organic materials, or by fusion or welding. After aligning the fiber 13 close to a position where the fiber tip does not touch the light transmitting member 15 of the package so that the laser beam B from the inside of the package can efficiently enter the fiber core, The outer surface 15a of the transmission member 15 is pressed against and fixed.

  As described above, according to the method for manufacturing a laser module of the present invention, since the deaeration process in the package can be performed before the optical fiber is attached to the package, the resin film of the optical fiber is used in the deaeration process in the package. There is no possibility that the inside of the package is contaminated by degassing from the container.

  As shown in FIG. 4 which is a partially enlarged side sectional view of another embodiment of the laser module, it is attached to fit the ferrule 20 so as to cover the light transmitting member 15 attached to the window 16 of the package 40. A vessel (receptacle) 25 may be attached. The receptacle 25 may be provided in the package 40 in advance, or may be attached after the package 40 is sealed. Attachment is performed using solder 18 so as to seal the inside of the package. By providing the receptacle 25, the mounting of the optical fiber 13 to the package 40 can be made simpler. As shown in FIG. 4, the ferrule 20 is fitted into the receptacle 40 and the tip of the optical fiber 13 is brought into close contact with the outer surface 15 a of the light transmitting member 15, and then the ferrule 20 and the receptacle 40 are fixed with solder 42. The ferrule 20 may be made of zirconia ceramic, metal, glass or the like.

  As shown in a partially enlarged side sectional view of still another embodiment in FIG. 5, spherical polishing is performed so that the end surface 20a of the ferrule 20 does not include air when pressed against the surface 15a ′ of the light transmitting member 15 ′. It is desirable to use In this way, the front end of the optical fiber is pressed against and closely adhered to the outer surface 15a 'of the light transmitting member 15', thereby removing outside air and preventing the incident end from being contaminated. Further, if glass having a convex surface as shown in FIG. 5 is used as the light transmitting member 15 ′, and the tip of the optical fiber 13 is pressed against the convex surface 15a ′ in the Y direction, air can be more effectively brought into close contact. It can be adhered while eliminating.

  Further, FIG. 6 shows a partially enlarged side sectional view of still another embodiment. In the laser module of the embodiment shown in FIG. 6, the package 40 includes the receptacle 25 as in FIG. 4, and the ferrule 20 further includes a connector 45 that fits into the receptacle 25. Instead of fixing the receptacle 25 and the ferrule 20 using solder, the connector 45 is fitted to the receptacle 25 and the ferrule 20 is fitted to the receptacle 25. The connector 45 includes a spring 46 and presses the ferrule 20 toward the light transmission member 15 from the rear end side of the ferrule 20. Since no solder is used, the attachment and removal of the optical fiber 13 is very simple.

  Note that the gas filling the package 40 is preferably mainly composed of an inert gas. Examples of the inert gas include nitrogen and rare gases. Further, it may be a mixed gas composed of an inert gas and at least one kind of oxygen of 1 ppm or more, a halogen group gas, and a halogen compound gas. For example, a clean gas that is a mixed gas of nitrogen and oxygen at the same ratio as the atmosphere. Air may be used.

  When oxygen having a concentration of 1 ppm or more is contained in the sealing atmosphere, deterioration of the laser module can be more effectively suppressed. The reason why such an effect of suppressing deterioration is obtained is that oxygen contained in the sealing atmosphere oxidizes and decomposes solid matter generated by photodecomposition of hydrocarbon components.

The halogen group gas is a halogen gas such as chlorine gas (Cl ₂ ), fluorine gas (F ₂ ), and the halogen compound gas is a chlorine atom (Cl), bromine atom (Br), iodine atom (I), A gaseous compound containing a halogen atom such as a fluorine atom (F).

Examples of the halogen compound gas include 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 can be mentioned, but fluorine or chlorine and carbon (C), nitrogen (N), sulfur (S), xenon (Xe) Compounds are preferred, and those containing fluorine atoms are particularly preferred.

  Although the halogen-based gas exhibits a deterioration suppressing effect even in a small amount, in order to obtain a remarkable deterioration suppressing effect, it is preferable that the content concentration of the halogen-based gas is 1 ppm or more. Such a deterioration suppressing effect is obtained because the halogen-based gas contained in the sealing atmosphere decomposes the deposit generated by the photodecomposition of the organosilicon compound gas.

  In addition, as described above, the lens array 11 and the condenser lens 12 are fixed inside the package, and the package is sealed, as described above, using flux-free solder or an adhesive that does not contain Si-based organic substances, or by fusion or welding. By fixing or sealing, dust collection can be further prevented.

  Examples of the adhesive containing no Si-based organic material include an adhesive composition containing an alicyclic epoxy compound described in JP-A-2001-177166, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoreaction initiator. It is a thing and consists of an adhesive composition which does not contain a silane coupling agent.

  Examples of the flux-free solder include Sn—Pb, Sn—In, Sn—Pb—In, Au—Sn, Ag—Sn, and Sn—Ag—In. Flux contained in normal solder material causes contamination, but there is no possibility of generating contaminants if flux-free solder is used. In consideration of the environment, it is desirable to use lead-free solder.

  Welding can be performed using a commercially available seam welder, for example, a seam welder manufactured by Nippon Avionics. Specifically, the package can be sealed by welding by placing a lid on the package and applying a high voltage to the boundary between the package lid and the housing with a seam welder. The fusion can be performed using a commercially available fusion machine, for example, FITEL S-2000.

  Next, a method for manufacturing a GaN-based semiconductor laser element will be described as an example of the semiconductor laser element used in the above embodiment. FIG. 7 is a cross-sectional view showing the manufacturing process of the GaN-based semiconductor laser device.

As shown in FIG. 7 (a), trimethylgallium (TMG) and ammonia are used as growth raw materials, silane gas is used as an n-type dopant gas, and cyclopentadienylmagnesium is used as a p-type dopant. Using (Cp2Mg), a GaN buffer layer 122 is formed on a (0001) C-plane sapphire substrate 121 at a temperature of 500 ° C. to a thickness of about 20 nm. Subsequently, the temperature is set to 1050 ° C., and the GaN layer 133 is grown to about 2 μm. On top of that, a SiO ₂ film 124 is formed, and after applying a resist 125, using ordinary lithography,

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

Next, as shown in FIG. 7B, after the resist layer 125 and the SiO ₂ film 124 are used as a mask, the buffer layer 122 and the GaN layer 123 are removed to the upper surface of the sapphire substrate 121 by dry etching using a chlorine-based gas. Then, 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. 7C, the GaN layer 126 is selectively grown by about 20 μm. At this time, due to the growth in the horizontal direction, the stripes are finally combined and the surface is flattened. At this time, threading dislocations are generated in the upper part of the line portion of the buffer layer 122 and the GaN layer 123, but threading dislocations are not generated in the GaN layer 126 between the line portions.

Next, an SiO ₂ film 127 is formed on the GaN layer 126. As shown in FIG. 7D, the SiO ₂ film 127 located at the center of the space portion between the line portions formed by the buffer layer 122 and the GaN layer 123 remaining is formed. ₂ Remove about 127 μm of film 127.

  Next, as shown in FIG. 7E, the growth temperature is set to 1050 ° C., and the GaN layer 128 is selectively grown to about 20 μm. At this time, due to the growth in the lateral direction, the stripes are finally combined and the surface is flattened.

Next, an SiO ₂ film 129 is formed on the GaN layer 128, and as shown in FIG. 7 (f), the SiO ₂ film 129 located at the center of the remaining SiO ₂ film 127 is removed by about 3 μm in width, and on that, Then, the growth temperature is set to 1050 ° C., and the GaN layer 130 is selectively grown to about 20 μm.

  Finally, as shown in FIG. 7G, after the n-GaN layer 131 is grown on the GaN substrate prepared as described above by about 100 to 200 μm, the sapphire substrate to the GaN layer 130 are removed, The n-GaN layer 131 is an n-type GaN substrate 141 shown in FIG. FIG. 8 is a cross-sectional view of a part of the wafer before cleaving for explaining the layer structure of the semiconductor laser element.

Next, as shown in FIG. 8, the n-GaN buffer layer 142 and 150 pairs of n-Al _0.14 Ga _0.86 N (2.5 nm) / GaN (on the n-type GaN substrate 141 manufactured as described above). 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 Laminate. Here, Mg is used as the p-type impurity. For the activation of Mg, either a heat treatment in a nitrogen atmosphere after growth or a growth in a nitrogen-rich atmosphere may be used.

Next, when fabricating a lateral single mode semiconductor laser, in order to form a stripe region in which the transverse mode is single, a SiO ₂ mask 150 having a stripe-shaped opening having a width of 1 to 3 μm is formed at a pitch of 100 to 500 μm. In the case of producing a horizontal multimode broad semiconductor laser, SiO ₂ masks 150 having stripe-shaped openings with a width of several to 50 μm are formed at a pitch of 100 to 500 μm. An output of about several hundred to 2,000 mW can be obtained from a lateral multimode broad semiconductor laser having a stripe region with a width of several to 50 μm.

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

  In the case of a multi-cavity semiconductor laser device, the cavity length is 100 to 1500 μm, preferably 400 μm, and the length in the direction of the emission point arrangement is cleaved to 1 cm, for example, and the cavity surface is coated with a high reflection and low reflection coating. For example, a bar-shaped element having 20 cavities is completed. In the case of forming a multi-cavity, the element is formed by cleaving with the element width in the light emitting point arrangement direction according to the required number of cavities.

  In the case of forming a single cavity semiconductor laser element, an element having a cavity length of 400 μm having a single cavity is formed by cleaving at a pitch of 100 to 500 μm, which is equal to the formation pitch of the stripe region.

  In addition, as a form of the semiconductor laser element accommodated in the package in the laser module of the present invention, one multicavity semiconductor laser element (in addition to the discrete single cavity chip shown in the above embodiment arranged in an array) LD bar), 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.

  FIG. 9 is a plan view of a laser module according to the second embodiment of the present invention.

  In the laser module according to the present embodiment, five chip-state single-cavity GaN-based semiconductor lasers LD 11 to LD 15 arranged on a heat block 70 and a condenser lens array 72 include a light transmission member 85. It is accommodated in a package 80 having a light exit window 86, and five optical fibers 73 are tightly fixed so as to press the incident end against the light transmitting member 85 outside the package 80. This laser module is a fiber array type laser module that couples laser beams emitted from semiconductor laser elements to different optical fibers.

  Laser beams B11-15 emitted from the GaN-based semiconductor laser elements LD11-15 in a divergent state are condensed by the respective condensing lenses constituting the condensing lens array 72, and are different on the outer surface of the light transmitting member 85, respectively. Converges to position. The tip ends of the five optical fibers 73 are inserted into the multi-fiber ferrule 90, and the incident ends are closely fixed to the convergence positions of the laser beams B11 to B15. Each of the laser beams B11 to 15 is coupled to a different optical fiber 73 and emitted from an emission end (not shown) of each optical fiber 73.

  Also in the laser module of the present embodiment, the package 80 is hermetically sealed after the deaeration treatment, and fixing of each member and package sealing are performed using a flux-free solder or an adhesive that does not contain Si-based organic substances, or It is done by fusing or welding. Accordingly, in the package 80, dust collection on the light emitting end surface of the semiconductor laser element having a high light density is suppressed, and the inner surface of the light transmissive member 85 is not a condensing point of the laser beam. The density is low and the dust collection effect on the surface is suppressed. Further, since the incident end of the optical fiber 73 is in close contact with the light transmitting member 85, it is not contaminated without being exposed to the atmosphere. Since the dust collection effect is suppressed as a whole of the laser module, the light output can be improved and high reliability can be obtained.

  FIG. 10 is a plan view of a laser module according to the third embodiment of the present invention.

  The laser module of this embodiment includes a GaN-based semiconductor laser element LD inside, a hermetically sealed CAN package 110, and a condensing lens 12 having a light exit window 16 provided with a light transmitting member 15. A single optical fiber 13 is housed in 40 and is fixed in close contact with the light transmitting member 15 by pressing its incident end outside the package 40. Here, elements equivalent to those of the laser module of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The CAN package 110 and the condensing lens 12 are arranged on each fixing member on the base plate 105 so that the laser beam B emitted from the semiconductor laser element LD is converged on the outer surface 15a of the light transmitting member 15 by the condensing lens 12. It is fixed. For each fixing, a flux-free solder or an adhesive containing no Si-based organic substance is used. It may be fixed by fusion or welding.

  In the present embodiment, the semiconductor laser element LD is provided in the CAN package 110. The CAN package is hermetically sealed after performing a deaeration process to remove internal volatile components. The semiconductor laser element LD is provided in a deaerated and hermetically sealed CAN package 110, and the optical fiber 13 is not arranged in the deaeration processing apparatus when the CAN package 110 is deaerated. The optical fiber 13 is not affected by degassing from the resin film. Further, since the CAN package 110 is provided in the hermetically sealed package 40, the dust collection effect can be further suppressed, and the light collection effect is suppressed as the entire laser module, so that the light output is improved. And high reliability can be obtained. In particular, when a high-power semiconductor laser device having an oscillation wavelength of 400 nm band such as a GaN-based semiconductor laser device manufactured by the above-described manufacturing method is provided, the dust collection effect is remarkable. The effect of providing a structure in which the laser element is included in a double package is great.

  The semiconductor laser element accommodated in the package includes one multi-cavity semiconductor laser element (LD bar), a plurality of discrete single-cavity chips arranged in an array, as shown in the above embodiment, and a plurality of semiconductor laser elements. It may be a multi-cavity semiconductor laser element arranged in an array, or a combination of a single-cavity semiconductor laser element and a multi-cavity semiconductor laser element.

The top view which shows schematic structure of the laser module by the 1st Embodiment of this invention Side view of laser module according to first embodiment Partially enlarged side sectional view of the laser module package Partially enlarged side sectional view of a laser module according to another embodiment The partially expanded side sectional view for demonstrating the manufacturing method of the laser module by other embodiment Partially enlarged plan view of a laser module according to another embodiment Sectional drawing which shows the substrate preparation method of a GaN-based semiconductor laser Sectional view for illustrating the layer structure of a GaN-based semiconductor laser device The top view which shows schematic structure of the laser module by the 2nd Embodiment of this invention Sectional drawing which shows schematic structure of the laser module by the 3rd Embodiment of this invention

Explanation of symbols

LD, LD1-8 Semiconductor laser element B, B1-8 Laser beam
10 Heat block
11 Lens array
12 Condensing lens
13 Optical fiber
13a Optical fiber
13b Resin coating
15 Light transmissive member
16 Light exit window
18 Solder
20 Ferrule
25 Receptacle
40 packages

Claims (9)

A hermetically sealed package with a light transmissive member in the light exit window;
One or more semiconductor laser elements disposed inside the package;
An optical fiber disposed outside the package;
A condensing optical system disposed inside the package for condensing a laser beam emitted from the semiconductor laser element on an outer surface of the light transmitting member;
An incident end of the optical fiber is fixed in close contact with a position on the outer surface of the light transmitting member where the laser beam is condensed.   The laser module according to claim 1, wherein a marker for determining a position for condensing the laser beam is attached to the light transmitting member.   3. The laser module according to claim 1, wherein the semiconductor laser element has an oscillation wavelength of 350 nm to 500 nm. The incident end of the optical fiber is inserted into the ferrule,
4. The laser module according to claim 1, wherein the package includes a mounting device that fits with the ferrule. 5.   The laser module according to any one of claims 1 to 4, wherein the package is filled with an inert gas.   6. The laser module according to claim 5, wherein oxygen, a halogen group gas, and / or a halogen compound gas having a concentration of 1 ppm or more are mixed in the inert gas.   7. The laser module according to claim 1, wherein the package is hermetically sealed using flux-free solder or an adhesive that does not contain Si-based organic matter, or by fusion bonding or welding. .   The semiconductor laser element includes a plurality of single cavity semiconductor laser elements arranged in an array, a multicavity semiconductor laser element, a plurality of multicavity semiconductor laser elements arranged in an array, and a single cavity semiconductor laser element and a multicavity 8. The laser module according to claim 1, wherein the laser module is one of a combination with a cavity semiconductor laser element. Manufacturing of a laser module comprising one or a plurality of semiconductor laser elements, an optical fiber, and a condensing optical system for condensing a laser beam emitted from the semiconductor laser element and coupling it to an incident end of the optical fiber In the method
The semiconductor laser element and the condensing optical system are disposed in a hermetically sealable package having a light exit window provided with a light transmitting member through which the laser beam is transmitted on one wall surface, and the laser beam transmits the light. Place it so that it is focused on the outer surface of the member,
Degassing the inside of the package;
After the deaeration treatment, the package is hermetically sealed,
Thereafter, the laser light beam is optically coupled to the incident end of the optical fiber so that the incident end of the optical fiber is fixed in contact with the outer surface of the light transmitting member. Method.

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