JP6527415B2 - Semiconductor laser device - Google Patents

Description

  The present invention relates to a semiconductor laser device, and more particularly to a surface emission type semiconductor laser device provided with a laser resonator in the horizontal direction of a semiconductor substrate and an inclined mirror for converting the emission direction of output light from the resonator.

  The lens-integrated semiconductor laser converts the emission direction of the output light of the semiconductor laser having a resonator in the horizontal direction of the substrate by a tilt mirror, and transmits and outputs a lens formed of InP. As a result, the output light converted into the desired spot size is efficiently coupled to the fiber or other optical element without using an external lens, and a low cost and low power consumption optical transmitter can be realized.

  A general lens-integrated semiconductor laser reflects output light toward the rear surface of the substrate by a tilted mirror, converts the output light into a desired spot size with a lens formed on the rear surface, and outputs it (see Non-Patent Document 1). FIG. 1 shows a lens integrated semiconductor laser shown in Non-Patent Document 1. As shown in FIG. FIG. 1 is a back view of a semiconductor laser device (hereinafter referred to as a back emission type semiconductor laser device) 100 in which an InP lens 106 is integrated on the back surface of an InP substrate on which a laser resonator 102 and a 45 ° inclined mirror 104 are formed. is there.

  On the other hand, there is also proposed a structure in which the light output from the surface of the substrate is obtained by jumping the light output from the laser to the surface (top) of the substrate by the tilt mirror (see Non-Patent Document 2). FIG. 2 shows a laser device (hereinafter, surface emission type semiconductor laser device) having a structure for obtaining light output from the substrate surface shown in Non-Patent Document 2. As shown in FIG. The surface emission type semiconductor laser device 200 of FIG. 2 is formed on the p-type electrode 220 formed on the surface of the substrate and the back surface of the substrate with respect to the Distributed FeedBack (DFB) diffraction grating provided active layer 213 formed on the substrate. A current is applied from the n-type electrode 222. The traveling direction of the output light from the active layer 213 is converted by the 45 ° tilt mirror 204, and the light is output from the small area 217 where the anti-reflection film is formed on the surface of the substrate.

  As shown in FIG. 3, in the surface emission type semiconductor laser device, by integrating InP lenses on the substrate surface, it is possible to convert output light into a desired spot size. The surface emission type semiconductor laser device of FIG. 3 is a semiconductor laser device (also referred to as a lens integrated type semiconductor laser device) in which a lens is integrated on the surface of a semiconductor substrate, and output light is obtained through the lens integrated on the surface. . The surface emission type semiconductor laser device 300 of FIG. 3 includes a laser resonator 302 formed on the surface side of an InP substrate in a direction parallel to the InP substrate, an optical waveguide 330, an inclined mirror 304, and an InP lens 306. Equipped with The laser resonator 302 includes a lower separated confinement (SCH) layer 310, an active layer (multiple quantum well) 312, an upper SCH 314, a diffraction grating 316, and an electrode 320 for applying a current to the laser resonator 302. The output light from the laser resonator 302 propagates through the waveguide 330, the traveling direction is converted by the 45 ° tilt mirror 204, and is converted into a desired spot size by the InP lens 306 integrated on the surface of the substrate. In this case, since alignment and fabrication processes of the tilt mirror 304 and the InP lens 306 are performed on the surface of the semiconductor substrate, it is possible to integrate the lens with high positioning accuracy by a general stepper process.

K. Adachi et al., “A 1.3-μm Lens-Integrated Horizontal-Cavity Surface-Emitting Laser with Direct and Highly Efficient Coupling to Optical Fibers,” Proc. Of Optical Fiber Communication, JThA31, Mar. 22-26, 2009 M. Mohrle et al., "1300-nm Horizontal-cavity surface-emitting BH-DFB lasers for uncooled operation," IEEE Photon. Technol. Lett., Vol. 18, No. 8, Apr. 2006

  However, in a back emission type semiconductor laser device in which a lens is integrated on the back surface of a semiconductor substrate, mass production is difficult because a special process for processing the back surface is required at the time of lens formation. Furthermore, since it is difficult to align the tilt mirror for converting the traveling direction of light formed on the front surface with the lens on the back surface, it is inevitable that optical loss due to optical axis deviation occurs.

  Further, in the surface emission type semiconductor laser device in which the lens is integrated on the substrate surface, since the inclined mirror and the lens are formed on the surface, high precision alignment by the normal stepper process is possible, but the cladding of the waveguide is The layer thickness and the InP lens diameter are restricted, and it is difficult to manufacture a lens shape having a desired curvature with high accuracy. This will be described with reference to FIG.

  FIG. 4 shows a light output portion of a lens integrated semiconductor laser device (surface emission type semiconductor laser device) 400 having a tilted mirror 404 and an InP lens 406 on its surface. Also shown in FIG. 4 is a waveguide 430 through which light from a laser resonator (not shown) propagates. The inclined mirror 400, which changes the traveling direction of light in the direction perpendicular to the substrate, forms a mirror surface at an angle of 45 ° to the light propagating through the waveguide 430 formed in the horizontal direction on the substrate . Therefore, as shown in FIG. 4, the radius of the InP lens (hereinafter referred to as lens radius) with respect to the thickness (hereinafter also referred to as cladding layer thickness) d of the cladding layer where the light whose traveling direction is changed propagates toward the substrate surface. Also, r) needs to be r <d. Furthermore, since the InP lens 406 is manufactured by etching away a part of the cladding layer, it is necessary to have a cladding layer thickness including the height of the InP lens. The InP lens radius needs to be designed as large as possible to improve the fabrication accuracy. However, since the cladding layer thickness of the upper part of the waveguide of a general optical semiconductor device is about 1.5 μm, the radius of the InP lens is also restricted to 1.5 μm or less, so it is difficult to process with sufficient fabrication accuracy there were. In addition, when the cladding layer thickness is increased in order to increase the lens radius r, the increase in the cladding layer thickness of the laser resonator portion causes the characteristic deterioration such as high resistance of the laser. In addition, since it is necessary to perform deep etching at the time of producing a tilted mirror, it has also become a factor of complication of the production process.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a semiconductor laser device in which a lens having an arbitrary curvature is integrated on the surface of a semiconductor substrate.

  In order to achieve such an object, a first aspect of the present invention is a semiconductor laser device. The semiconductor laser device includes a laser resonator emitting light in the horizontal direction with respect to the InP substrate, an inclined mirror converting the emission direction of the output light from the laser resonator, and an optical axis on the surface of the InP substrate. And a lens formed of a dielectric material. The inclined mirror is formed on the inclined surface of the recess on the surface of the InP substrate. The recesses in the surface of the InP substrate are planarized using a dielectric material, and the lens is located on the surface of the InP substrate including the planarized recesses.

  In one embodiment, the dielectric material is benzocyclobutene. In one embodiment, the dielectric material used to planarize the recess and the dielectric material forming the lens are identical. In one embodiment, the dielectric material used to planarize the recess and the dielectric material forming the lens are different. In one embodiment, a plurality of sets of laser resonators and lenses are arranged on an InP substrate.

  As described above, according to the present invention, in the surface emission type semiconductor laser device in which the lens is integrated on the surface of the semiconductor substrate, the recess formed in the preparation of the inclined mirror is planarized with a dielectric material, and a dielectric material is used. By forming the lens, it is possible to integrate lenses having arbitrary curvatures. As a result, the lens radius can be made into an arbitrary shape without depending on the cladding layer thickness, so that it can be converted into a desired spot size diameter.

It is a figure for demonstrating the semiconductor laser by which the lens was formed in the board | substrate back surface. It is sectional drawing for demonstrating the semiconductor laser by which the lens was formed in the substrate surface. It is sectional drawing of a lens integrated type semiconductor laser which has an InP lens on the surface. It is sectional drawing of the light emission part of a lens integrated type semiconductor laser which has an InP lens on the surface. It is sectional drawing of the light emission part of the semiconductor laser which has the planarization part by a dielectric material, and a dielectric lens. It is a graph explaining the design range of the radius and height of a lens. It is a figure explaining the tolerance range of the radius of a lens, (a) is a figure which shows the design value r of a lens radius, and the tolerance range Δr, (b) shows the relationship between the tolerance range Δr of the lens radius r and FIG. It is a figure of the lens integrated type semiconductor laser which integrated the BCB lens using the planarization process by BCB. (A)-(d) is a figure explaining the preparation processes of a lens integration type semiconductor laser which has a BCB lens produced using a BCB planarization process. It is a figure of the optical transmitter which used quartz system PLC by collimated light, and a BCB lens integrated type laser.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Although specific numerical examples will be used in the following description of the various embodiments, the present invention is not limited to such specific numerical examples, and loss of generality is due to other numerical values. It goes without saying that it can also be implemented.

  FIG. 5 is a cross-sectional view of the light emitting portion of the surface emission type semiconductor laser device 500 of the present embodiment. The surface emission type semiconductor laser device 500 shown in FIG. 5 includes an optical waveguide 530 formed in a direction horizontal to the substrate, an inclined mirror 504, and a dielectric lens 506. The inclined mirror 504 is formed on the inclined surface of the recess. The recess is deeper than the optical waveguide 530, and the inclined surface of the recess includes the cross section of the optical waveguide 530. The recess is planarized using dielectric 540, and dielectric lens 506 is located on the surface of the substrate including the planarized recess. The dielectric lens 506 is located on the optical axis of the surface of the substrate. For example, after planarizing the recess that is generated when the inclined mirror 504 is manufactured with the dielectric material 540, the dielectric material is further used to form the lens portion 506.

  FIG. 6 shows a designable range of an InP lens and a dielectric lens using benzocyclobutene (BCB) as a dielectric material. The designed lens surface was designed on the assumption that it was emitted from a semiconductor and optically coupled to an optical fiber (numerical aperture NA = 0.12). When designing an InP lens from FIG. 6, as described above, the lens radius r has a restriction of r <d with respect to the cladding layer thickness d. Further, since the InP lens is formed by etching a part of the cladding layer, the lens height needs to be smaller than the cladding layer thickness. Since the cladding layer thickness of a general semiconductor laser is about 1.5 μm, the designable range of the radius and height of the InP lens is limited to the range within the broken line in FIG. Therefore, when designing an InP lens for an optical fiber, it is necessary to produce an extremely small lens having a radius r of 1.5 μm or less and a height of 0.5 μm or less. On the other hand, in the present invention, since the dielectric material is used for flattening of the concave portion and production of the lens, there is no structural restriction on the size of the lens, and a lens of any size can be produced. In FIG. 6, a BCB with a refractive index n = 1.5 is used, and a lens surface having a steeper curve than InP is required because the refractive index is smaller than that of a semiconductor (n = 3.21). It can be decided.

  As shown in FIG. 7A, assuming that the tolerance range of the manufacturing error with respect to the design value r of the lens radius is the tolerance range Δr, the relationship between the design value r of the lens radius and the tolerance range Δr of the lens radius is shown in FIG. It becomes like (b). Here, the lens design assumes coupling to the optical fiber as in FIG. 6, and the range of the lens radius error is calculated such that the loss increases by 1 dB with respect to the ideal lens curvature. From FIG. 7, it is possible to increase the error allowance of the lens radius as the lens radius is designed to be larger. In the case of an InP lens, as described above, the lens radius is limited to 1.5 μm or less. Therefore, the error of the lens radius permitted from FIG. 6 is about 150 nm or less, and it is difficult to mass-produce the lens integrated structure with high accuracy and reproducibility. On the other hand, in the lens using BCB which is a dielectric material as in this embodiment, the radius can be increased, and an error tolerance of 200 nm or more, which can be sufficiently produced by a general stepper process, A sufficient value can be secured.

Example 1
FIG. 8 shows a lens integrated semiconductor laser device (surface emission type semiconductor laser device) in which BCB lenses are integrated using a planarization process by BCB according to an embodiment of the present invention. The surface emission type semiconductor laser device 800 of FIG. 8 includes a laser resonator 802 formed on the surface side of an InP substrate in a direction parallel to the InP substrate, an optical waveguide 830, an inclined mirror 804, and a BCB lens 806. Equipped with The laser resonator 802 includes a lower separated confinement (SCH) layer 810, an active layer (multiple quantum well) 812, an upper SCH 814, a diffraction grating 816, and an electrode 820 for applying a current to the laser resonator 802. The inclined mirror 804 is formed on the inclined surface of the recess. The recess is deeper than the optical waveguide 830, and the inclined surface of the recess includes the cross section of the optical waveguide 830. The recess is planarized using dielectric (BCB) 840, and dielectric lens 806 is located on the surface of the substrate including the planarized recess. The dielectric lens 806 is located on the optical axis of the surface of the substrate. The output light from the laser resonator 802 propagates through the waveguide 830, the traveling direction is converted by the 45 ° tilt mirror 804, and the desired spot size is converted by the BCB lens 806 integrated on the surface of the substrate.

  In order to manufacture the surface emission type semiconductor laser device 800, an initial substrate in which the lower SCH layer 810, the multiple quantum well layer 812 and the upper SCH layer 814 are grown on the n-InP substrate 801 is used. The production process is shown in FIG.

  First, the waveguide portion of the initial substrate is selectively etched, and waveguides 830 are formed by butt joint regrowth using, for example, InGaAsP (FIG. 9A). Subsequently, a diffraction grating 816 adjusted to operate at a 1.3 μm band as an oscillation wavelength is formed in the portion of the laser resonator 802, and a p-InP cladding layer (upper cladding layer) is formed by regrowth. I embedded the diffraction grating. The thickness of the cladding layer was 1.5 μm used in a general semiconductor laser. Next, a mesa structure was formed by etching, and a semi-insulating InP layer doped with Fe was formed on both sides of the mesa again by buried regrowth. The vertical direction of the resonator 802 has a laminated structure including a core layer (total layer thickness of 200 nm) consisting of a multiple quantum well 812 and upper and lower SCH layers (810 and 812) and an InP cladding layer sandwiching the core layer from the top and bottom In the horizontal direction, it has a buried hetero structure in which InP layers are formed on both sides of the mesa. The resonator 802 has a resonator length of 200 μm, a stripe width of 1.5 μm, and operates in the DFB mode due to the diffraction grating 816 formed in the resonator 802. Subsequently, an n-side (820) and a p-side electrode (not shown) are formed, and then an etching mask 972 is formed, and etching is performed at the end of the waveguide 830 with a 45 ° angle with the surface of the InP substrate 801 as a design value. Applied. At this time, the depth of the recess due to the etching was performed until the waveguide 830 was completely exposed and the lower portion of the waveguide 830 was exposed by about 2 μm (FIG. 9 (b)). Next, benzocyclobutene (hereinafter referred to as BCB), which is a dielectric material generally used for semiconductor optical devices, is coated on a substrate and solidified by baking, and then a concave portion (BCB) in which a portion of inclined mirror 804 is formed The BCB was etched so that the 840 became flat and the InP substrate surface was exposed in the other part (FIG. 9 (c)). Subsequently, a nonreflective coating (not shown) is applied on the substrate surface (a position corresponding to the surface of the substrate and the BCB lens) by sputtering, and BCB 974 is applied over the entire surface of the substrate again (FIG. 9D). Then, the BCB lens 806 was manufactured by performing and etching (FIG. 9 (e)). Here, a BCB lens was designed to couple the output light directly to the optical fiber (numerical aperture NA = 0.12), and the diameter was 5 μm and the height was 5.2 μm. As described with reference to FIG. 5, although the dielectric lens has a size that a part of the dielectric lens is applied to the concave when producing the inclined mirror, the lens shape is not affected because the above-described flattening process of the concave is performed. A uniform spherical surface was obtained. Here, although the same dielectric material BCB is used for flattening of the concave portion and formation of the lens, in the present invention, since the effect is exhibited by the combination of the flattening of the concave portion by the dielectric material and the lens formation It is also possible to use a dielectric material of For example, BCB may be used to planarize the recess, and a dielectric such as silicon dioxide (SiO 2) or an acrylic resin (PMMA) such as polymethyl methacrylate resin may be used to form the lens.

  Finally, a non-reflective coating was applied on the BCB lens to suppress reflected light at the boundary between BCB and air. First, the output light emitted from the end of the semiconductor laser resonator is optically coupled to the waveguide 830 and propagated, and then the traveling direction is converted to the substrate vertical direction by the inclined mirror 804 and reaches the BCB lens 806. The output light is condensed to a spot size matched to the optical fiber (NA = 0.12) by transmitting through the BCB lens.

  The effect of the BCB lens was estimated by directly optically coupling the surface emission type semiconductor laser device integrated with the prototyped BCB lens and the optical fiber. As a result, the coupling loss was about 3.0 dB without using an external lens or the like, and a loss improvement of about 10 dB was obtained as compared to the surface emission type semiconductor laser device in which the lens is not integrated. As described above, the cladding layer thickness is designed in accordance with a general semiconductor laser, and a lens integrated structure is realized without causing deterioration of laser characteristics.

(Example 2)
FIG. 10 is a cross-sectional view of a surface emission type laser device on which a plurality of laser resonators according to the present embodiment are mounted. The surface emission type laser device 1000 of FIG. 10 includes a plurality of sets of laser resonators 1002, a waveguide 1030, and a BCB lens 1006 arranged in parallel. The inclined mirror 1004 is formed on the inclined surface of the recess etched at one time. In addition, the recess is flattened by BCB. The BCB lens 1006 is located on the surface of the substrate including the recess flattened by BCB. The BCB lens 1006 is located on the optical axis of the surface of the substrate.

  The laser resonator 1002, the waveguide 1030, the inclined mirror 1004, the concave portion flattened by the BCB, and the BCB lens 1006 shown in FIG. 10 are the laser resonator 802, the optical waveguide 830, and the inclined mirror described with reference to FIG. 804, concave portions flattened by BCB, and BCB lenses 806, respectively.

  FIG. 10 also shows a multiplexing element 1050 made of a silica-based PLC that multiplexes the light from the surface emission type lens integrated laser element 1000. The wave combining element 1050 constitutes a multi-channel optical transmitter (also referred to as a WDM optical transmitter) together with the surface emission type lens integrated laser element 1000.

  The wave combining element 1050 condenses the light converted into collimated light by the BCB lens 1006 at the intersection of the inclined mirror 1054 and the silica based optical waveguide 1052 by the silica based lens 1056 integrated on the surface of the silica based substrate 1051. The traveling method can be converted by the tilt mirror 1054 and can be optically coupled to the silica-based optical waveguide 1052 with high efficiency. The silica-based optical waveguide 1052 is connected to an arrayed waveguide grating (AWG) manufactured on the silica-based substrate 1051, and can combine light input from each of the silica-based lenses 1056 with high efficiency.

  Here, a manufacturing process of the surface emission type semiconductor laser device 1000 mounting the four laser resonators 1002 will be described. As described with reference to FIG. 8, an initial substrate in which four sets (LANE 1 to 4) of a lower SCH layer, a multiple quantum well layer, and an upper SCH layer are grown in parallel on an n-InP substrate is used. First, after the waveguide 1030 and the laser resonator 1002 are formed by butt joint regrowth, the laser resonator 1002 has a 1.3 μm band as an oscillation wavelength, and for each of the four LANEs, LANE0 is 1294.53-1296.59 nm, A four-channel laser array grating (corresponding to grating 816) was formed that was tuned to operate with LANE1 at 1299.02-1301.09 nm, LANE2 at 1303.54-1305.63 nm, and LANE3 at 1308.09-1310.19 nm. Subsequently, a diffraction grating was embedded by forming a p-InP cladding layer by regrowth. The thickness of the cladding layer was 1.5 μm used in a general semiconductor laser. Next, a mesa structure was formed by etching, and a semi-insulating InP layer doped with Fe was formed on both sides of the mesa again by buried regrowth. The vertical direction of the resonator has a layered structure consisting of a core layer (total thickness of 200 nm) consisting of multiple quantum wells and upper and lower SCH layers and an InP cladding layer sandwiching the core layer from the top and bottom. It has a buried heterostructure in which an InP layer is formed. In all channels, the resonator length is 200 μm, the stripe width is 1.5 μm, and the device operates in the DFB mode due to the diffraction grating formed in the resonator. Each channel has a waveguide 1030 in communication with the end of the laser resonator 1002, and the output light from the laser resonator 1002 is optically coupled to the waveguide 1030 and propagated. Subsequently, n-side and p-side electrodes (not shown) are formed on all the laser resonators 1002, and the angle between the end of the waveguide 1020 of each channel and the surface of the InP substrate 1001 is 45 ° As an etching process, the inclined mirror 1004 was manufactured collectively. Next, benzocyclobutene (hereinafter referred to as BCB), which is a dielectric material generally used for semiconductor optical devices, is coated on a substrate and solidified by baking, and then inclined mirrors 1004 corresponding to each channel are formed. The BCB was etched so that the recess (BCB) 1040 became flat and the surface of the InP substrate was exposed at the other part. Subsequently, a non-reflective coating was applied on the substrate surface (a position corresponding to the surface of the substrate and the BCB lens) by sputtering, and BCB was applied over the entire surface of the substrate again to perform patterning and etching. . Here, a BCB lens was designed so that the output light was collimated light, and the diameter was 7.8 μm and the height was 4.8 μm for all channels. Although part of the BCB lens has a size related to the concave portion at the time of preparation of the inclined mirror, since the above-described flattening process of the concave portion is performed, the lens shape is not affected and a uniform spherical surface is obtained. Finally, a non-reflective coating was applied on the BCB lens to suppress reflected light at the boundary between BCB and air.

  The same dielectric material BCB is used to planarize the recess and form the lens, but in the present invention, different dielectric materials are used because they are effective by combining the recess planarization with the dielectric material and the lens formation. It is also possible to use For example, BCB may be used to planarize the recess, and a dielectric such as silicon dioxide (SiO 2) or an acrylic resin (PMMA) such as polymethyl methacrylate resin may be used to form the lens.

  4ch-PLC-AWG which has an inclined mirror 1054 and a lens 1056 made of a silica-based material on a silica-based substrate 1051 to the manufactured surface emitting type semiconductor laser device 1000 and can input and output light from the substrate surface A bonding experiment with the wave combining element 1050 was performed. The surface emission type semiconductor laser device 1000 and the multiplexing device 1050 made of silica-based PLC are optically coupled by collimated light. The alignment of the optical axis was performed by applying current to two of the four channels of the surface emission type semiconductor laser device 1000 and monitoring the output light from the multiplexing device 1050. After fixing the surface emitting type semiconductor laser element 1000 and the multiplexing element 1050, the evaluation results of the light emitted from the BCB lens 1006 of each channel and the coupling loss to the waveguide in the silica-based PLC of the multiplexing element 1050 are all It is confirmed that the coupling loss is 4 dB or less in the channel of. In addition, the total insertion loss including multiplexing loss in the multiplexing element 1050 made of silica-based PLC is estimated to be 5 dB or less for each channel, and from this, a highly efficient WDM optical transmitter is realized without using an external lens. It was done.

DESCRIPTION OF SYMBOLS 100 back emission type semiconductor laser device 102 laser resonator 104 45 ° inclined mirror 106 InP lens 200, 300, 400, 500, 800, 1000 surface emission type laser device 204 45 ° inclined mirror 213 Active with Distributed FeedBack (DFB) diffraction grating Layer 217 Small area formed with anti-reflection film 220 p-type electrode 222 n-type electrode 301, 801, 1001 InP substrate 302, 802, 1002 Laser resonator 304, 404, 504, 804, 1004 Tilting mirror 306, 406 InP lens 310 , 810 Lower SCH layer 312, 812 Active layer 314, 814 Upper SCH layer 316, 816 Diffraction grating
320, 820 Electrode 330, 430, 530, 830, 1030 Optical Waveguide 540, 840, 974, 1040 Dielectric 506, 806, 1006 Dielectric (BCB) Lens 972 Etching Mask 1050 Multiplexing Element 1051 Quartz Base Substrate 1052 Silica Base Conductor Waveguide 1054 Tilting mirror 1056 Silica-based lens

Claims (3)

A laser resonator for emitting light in the horizontal direction with respect to the InP substrate on an InP substrate; an inclined mirror formed on an inclined surface on the laser resonator side of a recess of a surface of the InP substrate; A semiconductor laser device comprising: an inclined mirror for converting the emission direction of output light from the laser; and a lens formed of a dielectric material on the optical axis of the surface of the InP substrate,
The recess in the surface of the InP substrate is planarized using a dielectric material,
The lens is formed on the surface of the InP substrate including the planarized concave portion at a position including the boundary between the planarized surface of the concave portion and the surface of the InP substrate and at the position of the inclined mirror. , A semiconductor laser device characterized in that.   2. The semiconductor laser device according to claim 1, wherein the dielectric material forming the lens and the dielectric material planarizing the recess are benzocyclobutene.   The semiconductor laser device according to claim 1, wherein a plurality of sets of the laser resonator and the lens are arranged on the InP substrate.