WO2006022162A1

WO2006022162A1 - Method for fabricating surface emission laser light source and surface emission laser light source

Info

Publication number: WO2006022162A1
Application number: PCT/JP2005/014909
Authority: WO
Inventors: Noriyuki Ohnoki; Atsushi Sugiyama
Original assignee: Hamamatsu Photonics K.K.
Priority date: 2004-08-25
Filing date: 2005-08-15
Publication date: 2006-03-02
Also published as: JP2006066538A

Abstract

A surface emission laser light source (2) comprising a surface emission laser element (3) having a columnar mesa shape and a microlens (4) formed integrally on a substrate (10). The surface emission laser element (3) is a vertical resonator surface emission laser (VCSEL) where a resonator is constituted between a lower mirror (5) and an upper mirror (8). The microlens (4) consists of a first lens part (4a) and a second lens part (4b) and has a distributed refractive index structure where the refractive index varies, in a specified distribution, from the central part on the exit face (3a) side toward the outer lens face (4c). Consequently, a fabrication method of a surface emission laser light source capable of obtaining laser light under desired exit conditions and a surface emission laser light source are realized.

Description

Specification

Surface emitting laser light source manufacturing method and surface emitting laser light source

Technical field

The present invention relates to a method for manufacturing a surface emitting laser light source and a surface emitting laser light source.

Background art

A vertical cavity surface emitting laser element having a structure that emits laser light perpendicular to a substrate surface can be integrated with other elements at high density on the substrate. The emission angle of the surface-emitting laser element is normally 6 to 7 degrees (in single mode), which is narrower than that of the edge-emitting laser element (about 30 degrees). Therefore, it is expected to be used in the future as a light source for optical integrated circuits. Further, various studies have been made on the laser light emission conditions of the surface emitting laser element (see, for example, Patent Documents 1 to 3).

Patent Document 1: Japanese Patent Laid-Open No. 2001-284725

Patent Document 2: JP 2002-26452 A

Patent Document 3: Japanese Patent Laid-Open No. 2001-242303

Disclosure of the invention

Problems to be solved by the invention

[0003] As described above, the surface emitting laser element can obtain laser light having a narrower emission angle than the edge emitting laser element. However, when applied to an optical interconnection in a state where elements such as a surface emitting laser element are highly integrated, it is necessary to further reduce the light emission angle from the surface emitting laser element. On the other hand, in the above document, a combination of a surface emitting laser element and a microlens is studied.

[0004] In Patent Document 1, a microlens is formed by extracting a resin with a nozzle on the upper part of a laser emitting unit and hardening the resin so as to have a convex lens shape. However, since the diameter of the laser emitting part is several / zm, it is difficult to align the position where the nozzles are used to draw the grease, and it is also difficult to form a microlens having a diameter of several meters. Furthermore, in order to integrate surface emitting laser light sources at high density, considering that they are formed in an array, one nozzle is used for each. This method of forming the coconut oil is not suitable for mass production. In Patent Document 2, a microlens having dielectric force is applied to a surface emitting laser light source. However, the specific lens structure and lens manufacturing method have been fully studied.

On the other hand, in Patent Document 3, a quartz lens is melted with heat to form a microlens! /

However, since the melting temperature of quartz glass is 1000 ° C or higher, the semiconductor substrate is thermally damaged and cannot be applied to a surface emitting laser light source.

[0006] The present invention has been made to solve the above-described problems, and provides a surface emitting laser light source manufacturing method and a surface emitting laser light source capable of obtaining laser light under desired emission conditions. Objective.

Means for solving the problem

In order to solve such an object, a method of manufacturing a surface emitting laser light source according to the present invention includes a first dielectric on a light emitting surface of a vertical cavity surface emitting laser element formed on a substrate. A first dielectric laminating step for laminating the material, a first lens forming step for forming the first dielectric material laminated on the emission surface on the original lens, and a second dielectric on the original lens. A second dielectric layer stacking process for stacking materials and a laser beam emitted from the surface emitting laser element, and based on the projected pattern, the outer surface of the second dielectric material stacked on the original lens And a second lens forming step for adjusting the shape to form a microlens corresponding to the surface emitting laser element.

[0008] According to this manufacturing method, the microlens is formed on the emission surface of the surface emitting laser element. Therefore, the emission angle of the laser light emitted from the surface emitting laser light source can be reduced, and further, collimated light can be obtained as necessary. In addition, the microlens is subjected to a two-step formation process in which an original lens is first formed and then a second dielectric material is laminated thereon. In such a method, the outer shape of the microlens finally obtained and the distributed refractive index structure in the lens can be variously controlled. Furthermore, once the laser beam is emitted and the emission pattern is confirmed, the shape of the microlens is adjusted. Therefore, in order to obtain a desired emission condition, the shape of the microlens can be controlled with high accuracy. Because it does not require complex adjustments for alignment! /, Lenses can be easily formed. A surface emitting laser light source according to the present invention includes a vertical cavity surface emitting laser element formed on a substrate, and a microlens formed on an emission surface of the surface emitting laser element. [0010] This surface emitting laser is characterized in that it is formed of a dielectric and has a distributed refractive index structure in which the refractive index changes with a predetermined distribution from the center on the exit surface side toward the outer lens surface. According to the light source, the microlens is formed on the emission surface of the surface emitting laser element. Therefore, the emission angle of the laser light emitted from the surface emitting laser light source can be reduced, and further, collimated light can be obtained as necessary. In addition, since the microlens has a distributed refractive index structure that changes its refractive index, the emission conditions of the laser light emitted from the surface emitting laser light source power can be variously controlled. In addition, since the microlens is formed on the emission surface of the surface emitting laser element, no complicated adjustment for alignment is required to align the microphone aperture lens. The emitting surface of the surface emitting laser element may be the surface opposite to the substrate or the surface on the substrate side.

The invention's effect

[0011] According to the present invention, it is possible to provide a surface emitting laser light source manufacturing method and a surface emitting laser light source capable of obtaining laser light under desired emission conditions.

Brief Description of Drawings

FIG. 1 is a perspective view showing a configuration of a surface emitting laser array according to a first embodiment.

FIG. 2 is a perspective view showing a configuration of a surface emitting laser light source according to the first embodiment.

FIG. 3 is a diagram showing a state in which outgoing light is refracted by the microlens of the first embodiment.

FIG. 4 is a diagram showing a state in which emitted light is reflected by the microlens of the first embodiment and returns to the inside of the surface emitting laser element.

FIG. 5 is a process sectional view showing a first dielectric layer stacking process and a first lens forming process.

FIG. 6 is a process cross-sectional view illustrating a second dielectric layer stacking process and a second lens forming process. FIG. 7 is an AFM measurement result showing a cross-sectional shape of the microlens.

[FIG. 8] FIG. 8 is a photograph of a microlens by an optical microscope.

FIG. 9 is a cross-sectional view showing a configuration of a surface emitting laser light source according to a second embodiment.

Explanation of symbols

[0013] 1 ... surface emitting laser array, 2, 20 ... surface emitting laser light source, 3 ... surface emitting laser element, 3a ... emitting surface, 4, 21 ... micro lens, 4a, 21a ... first lens section 4b, 21b ... second lens part, 4c, 21c ... lens surface, 5 ... lower mirror, 6 ... active layer, 7 ... oxide current confinement layer, 8 ... upper mirror, 10 ... substrate, 11 ... 1st SiN film, 12 ... resist film, 13 ... original lens, 14 ... 2nd SiN film, 15 ... micro lens, 21d ... first layer, 21e ... second layer, 21f ... Third layer. ··· The center point of the microlens.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of a method for manufacturing a surface-emitting laser light source and a surface-emitting laser light source according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional ratios in the drawings must be consistent with those in the description.

FIG. 1 is a perspective view of a surface emitting laser array 1 which is a surface emitting laser light source according to the present embodiment. The surface emitting laser array 1 includes a plurality of surface emitting laser light sources 2 arranged in a two-dimensional array on the same surface of the substrate 10 at regular intervals.

FIG. 2 is a perspective view of the surface emitting laser light source 2 according to the present embodiment, and FIG. 3 is a vertical sectional view of the surface emitting laser light source 2.

As shown in FIG. 2, the surface emitting laser light source 2 is configured by integrally forming a surface emitting laser element 3 having a cylindrical mesa shape and a microlens 4 on a substrate 10. ing. The surface emitting laser element 3 is a vertical cavity surface emitting laser (VCSEL), which is formed by stacking a lower mirror 5, an active layer 6, an oxide current confinement layer 7, and an upper mirror 8. A resonator is formed with the upper mirror 8. Therefore, as indicated by the arrows in FIG. 2, laser light is emitted in a direction parallel to the stacking direction of these layers.

[0018] The microlens 4 has a convex lens shape, and is formed integrally with the surface emitting laser element 3 on the emission surface 3a which is the surface opposite to the substrate 10 of the surface emitting laser element 3. Also micro The lens 4 is formed in a distributed refractive index structure in which the refractive index changes with a predetermined distribution by the central force on the exit surface 3a side also directed toward the outer lens surface 4c.

Specifically, the microlens 4 also has a SiN force, which is a dielectric, and as shown in FIG. 3, a center point (center) that is on the surface on the emission surface 3a side and intersects the optical axis. Part) An inner first lens part 4a including C and an outer second lens part 4b including a lens surface 4c which is an outer surface of the microlens 4 are configured. In the first lens unit 4a, the refractive index is uniformly distributed with a constant value. Further, in the second lens portion 4b, the refractive index is distributed so that the force on the first lens portion 4a side also decreases radially toward the lens surface 4c side.

Next, effects of the surface emitting laser array 1 and the surface emitting laser light source 2 will be described. The laser light emitted from the surface emitting laser element 3 is refracted by the microlens 4 and its emission angle becomes small. Therefore, it is possible to obtain laser light with a narrowed emission angle or collimated laser light as necessary. Therefore, when the surface-emitting laser array 1 or the surface-emitting laser light source 2 is applied to optical interconnection, it is possible to increase its integration and to suppress crosstalk between channels. The microlens 4 has a distributed refractive index structure in which the refractive index is distributed from the center point C toward the lens surface 4c. In such a configuration, the laser light emission conditions can be variously controlled by changing the specific distribution structure of the refractive index. The microlens 4 is formed on the emission surface 3 a of the surface emitting laser element 3. Therefore, it is possible to align the microlens 4 without making complex adjustments for alignment.

[0021] The distributed refractive index structure of the microlens 4 can take various structures.

For example, the second lens unit 4b has a structure in which the refractive index of the first lens unit 4a side force also changes toward the lens surface 4c side, so that a desired output can be obtained in combination with the first lens unit 4a. It is possible to control to the conditions.

[0022] Specifically, in the distributed refractive index structure of the microlens 4 in the present embodiment, the refractive index is uniformly distributed at a constant value in the first lens portion 4a, and the refractive index structure in the second lens portion 4b. In this structure, the rate changes so as to continuously decrease from the first lens portion 4a side toward the lens surface 4c side. Therefore, as shown in the optical path diagram of FIG. 3, the emitted laser light at each angle is gradually refracted in the vertical direction (upward), and the optical path length difference between these lights is reduced. So As a result, the aberration when the laser light emitted from the surface emitting laser light source 2 is condensed is reduced. As a result, when applied to devices such as high-speed optical parallel processing circuits that use femtosecond pulse waves, dispersion due to aberrations is reduced, and femtosecond pulse optical computers and other optical systems required for high-speed processing can be realized. It becomes.

[0023] The distributed refractive index structure of the microlens 4 is not limited to the above example. For example, the microlens 4 has a configuration in which the refractive index changes stepwise between the first lens unit 4a and the second lens unit 4b. Also good. In this way, when the refractive index is changed stepwise, as shown in FIG. 4, a part of the light is reflected at the interface between the first lens portion 4a and the second lens portion 4b, and the surface emitting laser is reflected. Returned inside element 3. Since the reflectivity depends on the difference in refractive index, it is possible to control the mode by adjusting the difference in refractive index so that the desired amount of reflection is obtained. In this case, the refractive index of the second lens portion 4b may be a continuously changing structure as described above, or may be constant. In the first lens portion 4a, the refractive index may be distributed so that the center point C force also continuously changes toward the interface with the second lens portion 4b. Alternatively, the distribution may be such that the refractive index changes stepwise within the first lens portion 4a. Furthermore, these distributions can be combined. As a result, an outgoing laser beam that satisfies a desired emission condition can be obtained.

[0024] Further, as described above, the surface emitting laser light source 2 has a reduced emission angle and reduced aberrations, so that the surface emitting laser array 1 in which the surface emitting laser light sources 2 are arranged at high density is possible. It becomes. Furthermore, if a large-scale high-power array having a high-density arrangement is realized, high-density light collection becomes possible. In the surface-emitting laser array 1, the arrangement of the surface-emitting laser light sources 2 is not limited to the two-dimensional array described above, and may be one-dimensional or two-dimensional array. Furthermore, when the surface emitting laser array 1 includes only one surface emitting laser light source 2, the surface emitting laser array 1 is not an array but a single surface emitting laser light source.

The surface emitting laser element 3 is not limited to the mesa type, but may be a buried type or a planar type. The dielectric material that forms the microlens is not limited to SiN.

Next, with reference to FIGS. 5 and 6, a method for manufacturing the surface-emitting laser light source 2 according to the present embodiment will be described.

Here, in the method for manufacturing the surface emitting laser light source 2 in the present embodiment, the microlens is formed by the laminated dielectric. Especially in the formation of microlenses, It is preferable to combine the features of Zuma CVD, reactive ion etching, plasma etching, and sputtering. Thereby, it is possible to freely adjust the lens curved surface of the microlens mounted on the surface emitting laser element 3. Since the plasma CVD method has no directionality with respect to stacking, the stack is stacked with a uniform thickness. In addition, since the plasma etching method has no directionality with respect to etching, it is etched with a uniform thickness with respect to the surface of the object to be etched. In addition, since the sputtering method has verticality with respect to the lamination, the laminated material is laminated on the curved surface while maintaining the curvature of the curved surface. In addition, since the reactive ion etching method is perpendicular to etching, the curved surface is etched while maintaining the curvature.

[0028] When SiN is laminated by the plasma CVD method, the refractive index of the laminate changes by changing the temperature during lamination. By taking advantage of this, it is possible to make the laminate a distributed refractive index structure in which the refractive index changes stepwise or continuously. As a result, it is possible to reduce aberrations by simply controlling the mode of the outgoing laser beam and controlling the outgoing pattern (outgoing angle).

The method for manufacturing the surface emitting laser light source 2 according to the present embodiment includes a first dielectric layer stacking step, a first lens forming step, a second dielectric layer stacking step, and a ^second lens forming step. It is out. Here, SiN is used as an example of a dielectric to be stacked.

FIG. 5A is a process cross-sectional view showing the first dielectric laminating process.

As shown in FIG. 5 (a), first, SiN, which is the first dielectric material, is formed on the emission surface 3a of the surface emitting laser element 3 formed on the substrate 10 by, eg, plasma CVD. By stacking, the first SiN film 11 is formed. The refractive index of the first SiN film 11 differs depending on the temperature at which the first dielectric material SiN is laminated. For example, when the film is laminated at 350 ° C., the refractive index of the first SiN film 11 is 2.5.

FIG. 5B to FIG. 5F are diagrams for explaining the first lens forming step.

[0033] As shown in FIG. 5 (b), first, a resist material (for example, S1818, manufactured by Shipley) is applied onto the first SiN film 11 laminated in the first dielectric laminating step, and the resist film Form 12. The resist material is applied, for example, by spin coating (rotation speed: 7000 rpm, processing time: 40 seconds). Next, as shown in FIG. 5C, the resist film 12 is shaped according to the mask pattern by performing exposure and development. The mask pattern is formed so that the resist film 12 remains on the emission surface 3 a of the surface emitting laser element 3.

Subsequently, as shown in FIG. 5 (d), the remaining resist film 12 is formed in a spherical shape by applying post-beta. Post beta is performed at a temperature of 200 ° C for 1 minute, for example.

Thereafter, as shown in FIG. 5 (e), the resist film 12 and the first SiN film 11 are etched by plasma etching to form the original lens 13 having a spherical shape, that is, a convex lens shape. Examples of gases used for plasma etching include tetrafluorocarbon (CF) and acid.

It is assumed to be 4 elementary (O). In this method, the surface of the original lens 13 is etched with a uniform thickness.

2

Therefore, the size and curvature of the original lens 13 can be adjusted by the etching time. That is, if the etching time is lengthened, the original lens 13 becomes smaller and its curvature becomes larger. On the other hand, if the etching time is shortened, the original lens 13 becomes larger and its curvature becomes smaller.

[0037] Thereafter, adjustment is performed as necessary so that the height of the original lens 13 formed on the substrate 10 is constant. FIG. 5 (f) shows a state where the original lens 13 is adjusted to be higher. When the height of the original lens 13 is lowered, a reactive ion etching method can be applied. In the reactive ion etching method, etching is performed while maintaining the curvature of the original lens 13. On the other hand, when the height of the original lens 13 is increased, a sputtering method is applied. In the sputtering method, the original lens 13 is laminated while maintaining the curvature.

As described above, the spherical original lens 13 is formed.

FIG. 6A is a process cross-sectional view showing the second dielectric laminating process.

As shown in FIG. 6 (a), SiN as the second dielectric material is laminated on the original lens 13 by plasma CVD to form a second SiN film 14. The refractive index of the second SiN film 14 depends on the temperature during deposition (film formation temperature). For example, the refractive index of the second SiN film 14 can be reduced by changing the second dielectric material continuously at a temperature of 350 ° C at which the first dielectric material is laminated, and lowering it to 250 ° C. The refractive index of the lens 13 continuously changes from 2.5 power to a refractive index of about 2.0 at the surface 14 a of the second SiN film 14. Further, the second dielectric material may be laminated at a temperature stepwise different from the temperature at which the first dielectric material is laminated. Alternatively, the temperature change at the time of stacking in the second dielectric stacking step may be stepwise rather than continuous. Or you may make the temperature at the time of lamination | stacking constant.

FIG. 6B shows a second lens forming process.

[0042] After emitting the laser beam from the surface emitting laser element 3 and confirming the emission pattern, the microlens 15 is configured to satisfy a desired emission condition (for example, collimated light or single mode maximization). Adjust the outer shape. A reactive ion etching method or a sputtering method is used to adjust the outer surface shape. As shown in FIG. 6B, the microlens 15 is composed of an original lens 13 and a second SiN film 14. In addition, the microlens 15 includes a first lens portion and a second lens portion. The first lens (power 4a in FIG. 3) including the center point C of the original lens 13 force microlens 15, the second lens portion, and the second lens portion. SiN film 14 force The second lens part (4b in Fig. 3) on the outside including the lens surface.

FIG. 6 (c) is a diagram showing a step of removing a portion unnecessary for forming the microlens 15. Specifically, a resist material is applied to the substrate 10 and notched, and then etched to remove a portion that is not necessary for forming the microlens 15. This process can be incorporated as needed and can be omitted.

Next, the effects of the method for manufacturing the surface emitting laser array and the surface emitting laser light source according to the present embodiment will be described. According to this manufacturing method, since the microlens 15 is formed on the emission surface 3a of the surface emitting laser element 3, the emission angle of the laser beam emitted from the manufactured surface emitting laser light source 2 can be reduced. it can. Therefore, laser light with a narrowed emission angle or collimated laser light can be obtained as necessary. This also makes it possible to suppress crosstalk when the surface emitting laser array 1 or the surface emitting laser light source 2 is applied to optical interconnection.

In addition, the microlens 15 is subjected to a two-stage formation process in which the original lens 13 is first formed and the second dielectric material is laminated thereon. For this reason, it is possible to variously control the outer surface shape of the finally obtained microlens and the distributed refractive index structure in the lens.

[0046] Further, after the laser beam is once emitted and the emission pattern is confirmed, the outer surface shape of the microlens 15 is adjusted. Therefore, high precision is required to obtain laser light according to the desired emission conditions. It is possible to control the lens shape in degrees. For example, the collimated light can be obtained by adjusting the outer surface shape of the microlens 15. Alternatively, the shape of the upper surface of the microlens 15 functioning as a concave mirror can be adjusted to control the light returning to the inside of the surface emitting laser element 3 to maximize the single mode output. In particular, it is possible to adjust the curved surface of the upper surface (lens surface) of the microlens 15 according to a desired emission condition by adjusting using an ion etching method or a sputtering method.

[0047] Furthermore, once the mask used in the first lens forming step is manufactured, the microlenses 15 can be formed in a large amount in a lump without taking time for alignment. For this reason, in the surface emitting laser light source 2 using the oxide film current confinement structure, the shape of a lens of several / zm diameter aligned on the active layer in the order of m order can be controlled. Mode output can be obtained. In particular, in the manufacture of the surface emitting laser array 1, since the microlenses 15 can be formed in a large amount in a lump, it can be manufactured at a low cost.

[0048] In addition, the second dielectric material is laminated so that the refractive index changes radially from the original lens 13 side to the outside (lens surface side) over the second dielectric lamination step. Is possible. As a result, the microlens 4 can have a distributed refractive index structure that matches a desired emission condition.

[0049] For example, the second dielectric material can be laminated so that the radial change in the refractive index in the second dielectric lamination step is continuous. As a result, it is possible to gradually refract the light of each angle emitted from the surface emitting laser element 3 in a desired direction. Specifically, by laminating so that the refractive index is radially reduced toward the lens surface, the optical path between the laser beams emitted from the surface emitting laser element 3 is emitted from the surface of the surface emitting laser element 3 outside the original lens 13. The length difference is reduced. As a result, the aberration when the laser light emitted from the surface emitting laser light source 2 is condensed is reduced, and this enables an array in which the surface emitting laser light sources 2 are arranged with high density.

[0050] Alternatively, the second dielectric material can be laminated so that the radial change of the refractive index in the second dielectric lamination step becomes stepwise. In such a configuration, at the interface where the refractive index in the second SiN film 14 changes stepwise, the surface emitting laser element can be introduced into the surface emitting laser element. Reflected light can be obtained. The amount of reflection is an amount corresponding to the difference in refractive index before and after the interface. By adjusting the number of interfaces and the refractive index difference at the interfaces, it is possible to control the mode by setting the amount of reflection of the microphone aperture lens into the surface emitting laser element to a desired value.

[0051] In particular, when the layer of the second dielectric material is SiN by the plasma CVD method, the refractive index of the second dielectric material is changed by changing the temperature at the time of stacking. Can be laminated. For example, when the temperature is continuously changed, the refractive index is continuously changed to be laminated. In addition, by laminating the second dielectric material at a temperature that is stepwise different from the temperature at which the first dielectric material was laminated, a step is performed at the interface between the original lens 13 and the second dielectric material. A refractive index difference is provided. At this interface, light is reflected back to the inside of the surface emitting laser element 3 with a reflection amount corresponding to the difference in refractive index. Therefore, by adjusting the refractive index difference at the interface, the amount of reflection of the microlens 15 into the surface-emitting laser element 3 can be set to a desired value, and mode control becomes possible. Alternatively, the refractive index of the second dielectric material can be changed stepwise by changing the temperature stepwise in the second dielectric material stack. Alternatively, the refractive index can be uniformly distributed at a constant value in the second SiN film 14 by keeping the temperature at the time of lamination constant.

[0052] In addition, it is preferable to adjust the outer surface shape of the microlens by a reactive ion etching method or a sputtering method after the second lens forming step. Thereby, the curved surface of the lens surface of the micro lens is adjusted.

[0053] Note that the film formation method is not limited to the plasma CVD method in the first dielectric laminating step, and may be a sputtering method, a vapor deposition method, or the like.

Here, for the microlens 15 manufactured by the manufacturing method of the present embodiment, FIG. 7 shows a cross-sectional shape measured by an atomic force microscope (AFM), and FIG. 8 shows a photograph by an optical microscope. The AFM measurement shows the cross-sectional shape of the original lens formed through the first lens formation step (b in Fig. 7) and the cross-sectional shape of the microlens after the second lens formation step (a in Fig. 7). ) And went about. The horizontal axis of the graph in FIG. 7 represents the position on the bottom of the cross section of the microlens, and the vertical axis represents the height of the microlens. Figure 7 shows the cross section of the microlens. The shape changes after the second dielectric layering process and the second lens forming process.

Next, a second embodiment of the surface emitting laser light source according to the present invention will be described in detail.

FIG. 9 is a vertical sectional view of the surface emitting laser light source 20 according to this embodiment. The surface emitting laser light source 20 is structurally different from the surface emitting laser light source 2 according to the first embodiment in that the refractive index change at the second lens unit 4b of the surface emitting laser light source 2 according to the first embodiment is continuous. On the other hand, the refractive index change in the second lens portion 21b of the surface emitting laser light source 20 is gradual.

The microlens 21 is made of SiN as a dielectric, and as shown in FIG. 9, the inner first lens portion 21a including the center point (center portion) C and the lens surface that is the outer surface of the microlens 21 And an outer second lens portion 21b including 21c. As shown in FIG. 9, the second lens unit 21b includes a first layer 21d, a second layer 21e, and a third layer 21f. These are formed in the order of the first layer 21d, the second layer 21e, and the third layer 21f from the first lens portion 21a side toward the lens surface 21c side. Further, the refractive index value takes a constant value in the first lens portion 21a and in each of the first to third layers 21d, 21e, and 21f.

[0057] These layers have different refractive index values. Specifically, the refractive index of the first lens portion 21a gradually changes from large to small to large to small until the third layer 21f of the second lens portion 21b. That is, the refractive index of the first lens portion 21a is n, and the first to third layers 21 of the second lens portion 21b.

21a

If the refractive indices of d, 21e and 21f are n, n and n, respectively,

21d 21e 21f

n> n, n <n ゝ n> n

21a 21d 21d 21e 21e 21f

Meet.

Next, the effect of the surface emitting laser light source 20 will be described. The laser light emitted from the surface emitting laser element 3 is refracted by the microlens 21 and the emission angle is reduced. Therefore, laser light with a narrowed emission angle or collimated laser light can be obtained as necessary. Therefore, when the surface-emitting laser light source 20 is applied to optical interconnection, it is possible to suppress the high integration and the crosstalk between channels. The microlens 21 has a distributed refractive index structure. Therefore, by changing the specific distribution structure of the refractive index, the laser beam emission conditions are variously controlled. I can do it. The microlens 21 is formed on the emission surface 3 a of the surface emitting laser element 3. Therefore, it is possible to align the micro lens 21 without performing complicated adjustments for alignment.

[0059] The distributed refractive index structure of the microlens 21 in the present embodiment is a configuration in which the refractive index changes stepwise between the first lens portion 21a and the second lens portion 21b. Therefore, a part of the light is reflected at the interface between the first lens portion 21a and the second lens portion 21b and returned to the inside of the surface emitting laser element 3.

[0060] Further, the refractive index is uniformly distributed at a constant value in the first lens unit 21a, and the refractive index in the second lens unit 21b is stepwise toward the first lens unit 21a side force lens surface 21c side. It has changed. Therefore, as shown in FIG. 9, in addition to the interface between the first lens portion 21a and the second lens portion 21b, part of the light is also present at the interfaces between the layers 21d, 21e, and 21f in the second lens portion 21b. The light is reflected and returned to the inside of the surface emitting laser element 3. Thus, since the surface emitting laser light source 21 has a large number of interfaces whose refractive index changes stepwise, a high single mode property can be realized. Further, since the reflectance at each interface depends on the difference in refractive index before and after the interface, it is possible to control the mode by adjusting the difference in refractive index between the layers so as to obtain a desired amount of reflection.

Note that the refractive index change in the second lens portion 21b is not limited to that according to the present embodiment. For example, the refractive index may be changed in order from small → large → small → large in order from the first lens portion 21a to the third layer 21f of the second lens portion 21b. Alternatively, a configuration that changes from large to large or small to small may be included. The number of layers constituting the second lens portion 21b is not limited to three. Furthermore, the refractive index may continuously change in each layer.

[0062] In this case, in the first lens portion 21a, the refractive index may be distributed such that the center point C force also continuously changes toward the interface with the second lens portion 21b. Alternatively, the distribution may be such that the refractive index changes stepwise within the first lens unit 2 la. Furthermore, the above-described distribution example of the first lens portion 21a and the distribution example of the second lens portion 21b can be combined. As a result, an emitted laser beam that satisfies the desired emission condition can be obtained.

[0063] While the preferred embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the above embodiment. For example, in the above embodiment, the surface emitting laser element The output surface of the force may have been the surface on the opposite side of the substrate.

[0064] In addition, in order to collectively form the microlens 15 that precisely controls the angle of the emitted light (collimated light, etc.), a distributed refractive index structure conforming to the structure of the surface emitting laser element 3 is calculated. In order to achieve this, it is possible to obtain the curvature of the original lens 13, the refractive index distribution of the second dielectric material, and the outer surface shape of the microlens 15 while confirming the emission angle. It is done.

Here, the method for manufacturing the surface emitting laser light source includes a first dielectric laminate in which a first dielectric material is laminated on an emission surface of a vertical cavity surface emitting laser element formed on a substrate. A first lens forming step for forming a first dielectric material laminated on the exit surface on the original lens; and a second dielectric laminate for laminating the second dielectric material on the original lens Laser light is emitted from the surface emitting laser element, and the outer surface shape of the second dielectric material stacked on the original lens is adjusted based on the emission pattern to support the surface emitting laser element. And a second lens forming step of forming a microphone opening lens.

In the second dielectric layer stacking step, it is preferable to stack the second dielectric material by providing a stepwise difference in refractive index from the refractive index of the original lens. With such a configuration, reflected light to the inside of the surface emitting laser element can be obtained at the interface between the first and second dielectric materials with a reflection amount corresponding to the difference in refractive index. Therefore, by adjusting the refractive index difference, the amount of reflection of the microlens into the surface emitting laser element can be set to a desired value, and the mode can be controlled.

[0067] In addition, it is preferable to laminate the second dielectric material so that the refractive index changes toward the outside from the original lens side over the second dielectric laminating step. Thereby, it is possible to obtain a microlens having a distributed refractive index structure adapted to a desired emission condition.

[0068] Further, during the second dielectric laminating step, the second dielectric material may be laminated so that the refractive index continuously changes from the original lens side toward the outside. preferable. By changing the refractive index in this way, light at each angle emitted from the surface emitting laser light source can be gradually refracted in a desired direction, and the optical path length difference can be reduced. Thereby, the aberration of the light emitted from the surface emitting laser light source can be reduced.

[0069] In addition, during the second dielectric laminating step, the refractive index increases toward the outside from the original lens side. The second dielectric material is preferably laminated so as to change in a stepwise manner. At the interface where the refractive index changes stepwise, it is possible to obtain reflected light into the surface emitting laser element with an amount of reflection corresponding to the difference in refractive index before and after the interface. By adjusting the number of interfaces and the refractive index difference at the interfaces, it is possible to control the mode by setting the amount of reflection of the microlens into the surface emitting laser element to a desired value.

[0070] Further, it is preferable that the second dielectric material is laminated by a plasma CVD method in the second dielectric laminating step. In the plasma CVD method, especially in the case of SiN film formation, the refractive index is 2.5 around 350 ° C, but when the film formation temperature is lowered, H (hydrogen) is mixed and the refractive index decreases. For this reason, it is possible to change the refractive index distribution in the thickness direction by changing the temperature at the time of lamination. For SiO, Ge

It is also possible to change the refractive index by doping with 2, P, B, etc. Even in other materials, the microlens can be formed by changing the refractive index of the dielectric to be laminated by changing each film forming condition.

[0071] Further, it is preferable to adjust the outer surface shape of the microlens by a reactive ion etching method or a sputtering method after the second lens forming step. Thereby, the curved surface of the lens surface of the micro lens can be adjusted.

[0072] Further, the surface emitting laser light source includes a vertical cavity surface emitting laser element formed on a substrate and a microlens formed on an emission surface of the surface emitting laser element. Is formed in a distributed refractive index structure in which the refractive index changes with a predetermined distribution toward the outer lens surface as well as the dielectric force! I prefer to speak.

[0073] As a specific distributed refractive index structure, the microlens includes an inner first lens portion including a center portion and an outer second lens portion including a lens surface, and the first lens portion and the second lens portion. It is preferable that the refractive index changes stepwise with the lens unit. At the interface between the first lens unit and the second lens unit and the surface of the second lens unit, reflected light into the surface emitting laser element can be obtained with a reflection amount corresponding to the difference in refractive index. Therefore, it is possible to control the mode by adjusting the difference in refractive index so that the reflection amount into the surface emitting laser element inside the microlens becomes a desired value.

[0074] Further, the microlens includes an inner first lens portion including a central portion and an outer first surface including a lens surface. It is preferable that the second lens unit includes a second lens unit, and the refractive index of the second lens unit changes from the first lens unit side toward the lens surface side. Thereby, it is possible to control to a desired projection condition in combination with the first lens unit.

[0075] In this case, it is preferable that the change in the refractive index from the first lens unit side toward the lens surface side in the second lens unit is continuous. By changing the refractive index in this way, light at each angle emitted from the surface emitting laser light source can be gradually refracted in a desired direction, and the optical path length difference can be reduced. Thereby, the convergence of the light emitted from the surface emitting laser light source can be reduced.

[0076] Further, it is preferable that the refractive index change from the first lens unit side to the lens surface side in the second lens unit is stepwise. In such a configuration, at the interface where the refractive index in the second lens portion changes stepwise, the reflected light to the inside of the surface emitting laser element can be obtained with a reflection amount according to the refractive index difference before and after the interface. Can do. By adjusting the number of interfaces and the refractive index difference at the interfaces, the amount of reflection of the microlens into the surface emitting laser element can be set to a desired value, and the mode can be controlled.

[0077] In addition, in the surface emitting laser light source, a plurality of surface emitting laser elements and corresponding microlenses may be formed on the substrate in a one-dimensional or two-dimensional array. In the surface emitting laser light source described above, since the emission angle of the laser light can be suppressed, it is possible to form an array with high density.

Industrial applicability

The present invention can be used as a surface emitting laser light source manufacturing method and a surface emitting laser light source capable of obtaining laser light under desired emission conditions.

Claims

The scope of the claims

[1] a first dielectric laminating step of laminating a first dielectric material on an emission surface of a vertical cavity surface emitting laser element formed on a substrate;

A first lens forming step of forming, on an original lens, the first dielectric material laminated on the emission surface;

A second dielectric laminating step of laminating a second dielectric material on the original lens; and laser light is emitted from the surface emitting laser element, and is laminated on the original lens based on the emission pattern. Adjusting the outer surface shape of the second dielectric material to form a microlens corresponding to the surface emitting laser element;

A method of manufacturing a surface emitting laser light source, comprising:

[2] In the second dielectric layer stacking step, the second dielectric material is stacked in a stepwise difference in refractive index from the refractive index of the original lens. A method for manufacturing a surface emitting laser light source according to claim 1.

[3] The second dielectric material is laminated such that, in the second dielectric laminating step, the refractive index changes from the original lens side toward the outside. The manufacturing method of the surface emitting laser light source of description.

[4] In the second dielectric laminating step, the second dielectric material is laminated so that the refractive index continuously changes from the original lens side toward the outside. A method for manufacturing a surface emitting laser light source according to claim 3.

[5] In the second dielectric laminating step, the second dielectric material is laminated so that the refractive index changes stepwise from the original lens side toward the outside. 5. A method for producing a surface emitting laser light source according to claim 3 or 4.

[6] The surface according to any one of claims 1 to 5, wherein, in the second dielectric laminating step, the second dielectric material is laminated by a plasma CVD method. Manufacturing method of light emitting laser light source.

[7] The surface according to any one of [1] to [6], wherein in the second lens forming step, an outer surface shape of the microlens is adjusted by a reactive ion etching method or a sputtering method. Manufacturing method of light emitting laser light source.

[8] A vertical cavity surface emitting laser element formed on a substrate;

A microlens formed on the exit surface of the surface-emitting laser element, and the microlens has a refractive index with a predetermined distribution toward a lens surface outside the central force on the exit surface side as a dielectric force. A surface-emitting laser light source characterized by being formed in a changing refractive index structure.

[9] The microlens includes an inner first lens portion including the central portion and an outer second lens portion including the lens surface, and is provided between the first lens portion and the second lens portion. 9. The surface emitting laser light source according to claim 8, wherein the refractive index changes step by step.

[10] The microlens includes an inner first lens portion including the center portion and an outer second lens portion including the lens surface, and the second lens portion is formed from the first lens portion side. 10. The surface emitting laser light source according to claim 8, wherein a refractive index changes toward the lens surface side.

11. The surface emitting laser light source according to claim 10, wherein the change in the refractive index from the first lens portion side to the lens surface side in the second lens portion is continuous. .

12. The surface emitting laser according to claim 10, wherein the change in the refractive index from the first lens unit side to the lens surface side in the second lens unit is stepwise. One light source.

13. The surface emitting laser according to any one of claims 8 to 12, wherein a plurality of the surface emitting laser elements and the corresponding microlenses are formed on the substrate in a one-dimensional or two-dimensional array. light source.