JP6393221B2 - Optical transmitter and optical transmitter - Google Patents

Description

  The present invention relates to an optical transmitter and an optical transmitter used for optical communication, and more specifically, a semiconductor laser element having a resonator that is guided in a horizontal direction of a semiconductor substrate, and an output direction of output light from the laser element as a substrate In an optical transmitter having an inclined mirror that converts in the vertical direction, a configuration that facilitates optical axis alignment (alignment, alignment) of an optical beam at the time of optical coupling between the optical transmitter and another optical circuit, and the optical transmitter The present invention relates to an optical transmission device using the.

  Development of 100 Gigabit Ethernet (100 GbE) using wavelength division multiplexing (WDM) technology in optical communication is progressing as one of the standards constituting the next-generation ultrahigh-speed network.

  In particular, 100GBASE-LR4 and 100GBASE-ER4 that exchange data between medium and long-distance buildings (-10 km) and remote buildings (-40 km) are promising.

  In the above-mentioned standard, four wavelengths (for example, 1294.53 to 1296.59 nm, 1299.02 to 1301.09 nm, 1303.54 to 1305.63 nm, and 1308.09 to 1310.19 nm) are defined. ), A LAN-WDM method is used in which 25 Gb / s (or 28 Gb / s) data is placed on each of the data and then superimposed to generate a 100 Gb / s signal.

  As described above, in Ethernet (registered trademark), studies aiming to increase the transmission capacity by wavelength multiplexing have been conducted. As one of optical devices that realize such an optical network, a wavelength multiplexing optical transmitter is used. Is being considered.

  The components of the wavelength division multiplexing optical transmitter are roughly classified into two functions: a function of converting an electrical signal into an optical signal, and a function of combining these optical signals.

  The former includes a direct modulation type DFB laser (distributed feedback laser) or a combination of a CW type DFB laser and an electroabsorption (EA) type optical modulator, and the latter includes multimode interference (MMI). Examples include a Multi Mode Interference (MUX) type multiplexer and an AWG (Arrayed Waveguide Grating) type multiplexer.

  As a wavelength multiplexing transmitter in which these components are integrated, a monolithic integrated light source based on an InP semiconductor material has been proposed (see Non-Patent Document 1 below).

  In this example, four electroabsorption modulator integrated lasers and an MMI type multiplexer are monolithically integrated on one chip to realize a compact and highly functional wavelength multiplexing transmitter.

  In the future, in order to further expand communication capacity, lasers are arrayed and high-density wavelength multiplexing is promising. However, it is considered that a highly accurate AWG is required as a multiplexer that bundles these signals.

  As an optical device platform for realizing such an AWG, for example, a quartz-based planar lightwave circuit (PLC) formed on a silicon (Si) substrate is known.

  The PLC is a waveguide type optical device with excellent characteristics such as low loss, high reliability, and high design flexibility. Actually, the transmission equipment at the optical communication transmission end has functions such as multiplexer / demultiplexer, branch / coupler, etc. A PLC in which is integrated is mounted.

  In addition, an optoelectronic integrated device in which a laser that is a light source and a PLC that performs optical signal processing are integrated in a hybrid manner has also been proposed (see Patent Document 1 below), and it is possible to combine an optimum device for a required function. Therefore, this is a promising approach for realizing a higher-performance integrated optical device.

In such a device, for example, as shown in FIG. 7 and the cross-sectional view of FIG. 2 of Non-Patent Document 2, a groove and a terrace region (the waveguide 74b of the PLC 74 and the activity in the substrate of the laser 72 are formed in a part of the PLC. A region for forming a step for making the height of the layer 72a the same), and a method of performing optical coupling by mounting the laser while aligning the laser with respect to the waveguide on the end face is adopted. A certain mounting area such as a groove or a terrace (“Silicon terrace” in FIG. 7) is required.
The “mounting area” here assumes the area of all structures necessary for mounting, such as grooves, silicon terraces, wiring, and markers for mounting, in addition to the semiconductor chip.

  Further, in this case, it is necessary to strictly control the alignment so that the height of the waveguide of the PLC and the height of the active layer of the laser substantially coincide (for example, with an accuracy of 0.5 μm or less). However, it is necessary to increase the accuracy of the manufacturing process and the accuracy of the film thickness of the solder 73 for mounting the laser.

  More specifically, in the laminated sectional view of the PLC 74 and the laser 72 in FIG. 7, the laser 72 is moved freely while being aligned in the X direction and the Z direction within the substrate surface of the PLC 74 so as to be adjusted to the optimum position. Can do. For example, in the X-axis direction, excess loss of coupling can be suppressed to 1 dB or less by adjusting to an optimum position with an accuracy of 0.5 μm when there is no spot size conversion in the laser and 2 μm or less when there is spot size conversion. . Further, when there is no spot size conversion in the Z-axis direction, the excess loss of coupling can be suppressed to 1 dB or less by adjusting to the optimum position with an accuracy of 5 μm when there is spot size conversion and 10 μm or less.

  On the other hand, the Y-axis direction perpendicular to the substrate surface of the PLC 74 is optimal because the positional relationship between the PLC and the laser is determined by the accuracy of the PLC creation and the accuracy of the film thickness of the solder 73 for mounting the laser 72. It was difficult to adjust the position.

Therefore, two opposed 45-degree mirrors for optical path conversion are provided in a corresponding part of the waveguide of the PLC and the laser chip, and the laser light emitted from the mirror of the laser chip in the direction out of the substrate surface is provided. Attention has been focused on a method of forming an optical coupling part that performs optical coupling with a PLC-side optical waveguide by changing the optical path of the light from the laser with a PLC-side mirror by mounting so as to receive light with a PLC mirror. (See FIGS. 8 and 9. The same parts as those in FIG.
Such a stack mounting type integrated device structure in which the optical coupling mirrors 72e and 74e are respectively mounted on the laser chip 72 and the PLC 74 and mounted in a stacked manner is slightly disadvantageous for the heat radiation of the laser, but is shown in FIG. Therefore, the area in the plane direction can be reduced accordingly, and there are advantages in terms of downsizing of the device and the degree of freedom in designing the lightwave circuit. In particular, from the point of alignment (optical axis alignment, alignment) of the optical coupling portion, alignment in the Y-axis direction is not necessary, and there is a great advantage that only alignment of the X-axis and Z-axis is required.

Japanese Patent No. 3890281 JP 2012-42515 A

T. Fujisawa, S. Kanazawa, H. Ishii, N. Nunoya, Y. Kawaguchi, A. Ohki, N. Fujiwara, K. Takahata, R. Iga, F. Kano, and H. Oohashi: "1.3-μm, 4 × 25-Gbit / s, monolithically integrated light source for metro area 100-Gbit / s Ethernet, "IEEE Photonics Technology Letters, Vol.23, No.6, pp.356-358, March 15 2011. Toshikazu Hashimoto, Yoshinori Nakasuga, Yasufumi Yamada, Hiroshi Terui, Masahiro Yanagisawa, Yuji Akahori, Yuichi Tohmori, Kazutoshi Kato, and Yasuhiro Suzuki, "Multichip Optical Hybrid Integration Technique with Planar Lightwave Circuit Platform", JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 16, NO. 7, JULY 1998, pp. 1249-1258.

  There are roughly two methods for optical axis alignment and alignment in the light beam coupling portion when mounting a laser chip substrate in such a PLC.

  First, the intensity of light incident on the optical waveguide side (PLC side) can be monitored, and the laser is driven to emit the beam to the mirror side, so that the position at which the coupling efficiency is high becomes high ( This is a method of aligning and fixing the laser chip (active alignment) so that the intensity of light to be monitored increases.

  Secondly, alignment markers corresponding to the laser chip and the PLC are provided without driving the laser, the infrared light is transmitted from the back of the Si, and the marker is recognized by image recognition while looking at the laser chip and PLC markers. In this method, the laser chips are fixed by aligning each other (passive alignment).

  Either method can be used for highly accurate alignment and stack mounting. Comparing the above two approaches in terms of optical coupling efficiency, the former active alignment which is implemented while monitoring the light intensity is more advantageous.

  However, for example, assuming a stack mounting of a laser array chip in which a plurality of lasers are integrated and a PLC chip in which a multiplexer is integrated, the output from the plurality of lasers is coupled to the PLC, and the intensity of the combined light is monitored. Will be aligned. For example, when a laser array substrate (bottom) consisting of four lasers as shown in FIG. 6 described later is mounted on the PLC (top), the PLC inputs the light of the four lasers, After being combined by the “multiplexer”, the single output is monitored (at the left end).

  In such stack alignment of laser array chips, it is necessary to adjust the tilt of the chip (the inclination of the PLC chip substrate surface with respect to the laser chip substrate surface) in addition to up / down / left / right and rotation.

  In other words, it is desirable to monitor the output of multiple lasers in order to adjust the vertical direction, rotation, and tilt of the chip, but it is difficult to drive multiple lasers at the same time because the alignment method is complicated and it is difficult to drive simultaneously. It is. Also, it is difficult and difficult to perform alignment by driving the lasers one by one and switching the operating lasers. Therefore, usually, simple alignment is usually performed by operating only one laser. In this case, however, adjustment is made by trial and error, and complicated alignment is necessary.

  In contrast, by providing a separate alignment light output on the substrate of the laser chip or laser array chip, and providing an alignment port on the PLC, the light intensity of the alignment light can be monitored together to adjust the position. Although an easy configuration is conceivable, a laser for alignment light is separately integrated on the laser chip or laser array chip substrate, and it is necessary to perform alignment by operating a laser that does not send signals during actual use. It becomes complicated.

  As described above, a small and high-performance integrated device can be expected by stack mounting. On the other hand, in the laser array and PLC hybrid, the alignment laser is separately integrated and the structure becomes complicated to operate it. There is.

  Therefore, in stack mounting by optical coupling using a mirror between a PLC and a laser chip, a structure capable of realizing the alignment of the optical coupling portion between the laser and the PLC with a simple configuration and with a simple configuration is omitted. The realization of the optical transmitter provided with is a problem.

  The present invention has been made in view of such a problem. In stack mounting of a laser substrate and a PLC by optical coupling using a mirror, alignment can be easily performed, and the following structure having a simple structure is provided. An optical transmitter is provided.

An optical transmitter at least one laser is provided on the substrate, an output waveguide of the signal light output waveguide and the alignment light is provided at both ends of at least one of said laser, before SL signal light and the alignment light ahead of said output waveguide, the mirror are respectively provided to the optical path converting said signal light and the alignment light to said output waveguide of the prior SL signal light or the alignment light, the propagation direction of the alignment light and the signal light Is provided in the substrate plane, and the output waveguide of the alignment light is provided with a structure for branching the alignment light into two or more before the optical path conversion. A mirror that converts the optical path is also provided at the tip of the output waveguide of the alignment light, and the angle between the substrate surface and the reflecting surface of the mirror is mirrored. When the angle is set, the mirror angle is set between 30 degrees and 60 degrees, and at least three mirrors that change the optical path together with one of the signal lights are provided, and at least three of the mirrors are in a straight line. An optical transmitter, characterized in that the optical transmitter is formed at a position that does not .

  According to the present invention, in the stack mounting of the laser substrate, the alignment of the optical coupling portion using the mirror between the laser substrate and the optical circuit element such as the PLC can be easily performed without separately providing an alignment laser. Therefore, it is possible to provide an optical transmitter and an optical transmitter having a simple structure.

It is a block diagram which shows Example 1 of this invention. It is a figure which shows the laser substrate of Example 2 of this invention. It is a laser substrate partial sectional view of Example 2 of the present invention. It is a figure which shows PLC of Example 2 of this invention. It is PLC partial sectional drawing of Example 2 of this invention. It is a figure which shows the stack mounting example of the laser substrate of Example 2 of this invention, and PLC. It is sectional drawing of the optical coupling part of the conventional laser substrate and PLC. It is sectional drawing of the optical coupling part by the conventional laser substrate and the optical path conversion mirror of PLC. It is sectional drawing of another optical coupling part by the conventional laser substrate and the optical path conversion mirror of PLC.

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

Example 1
FIG. 1 shows a basic configuration of an optical transmitter and an optical transmitter as Embodiment 1 of the present invention.

  First, on a semiconductor substrate 1 such as InP, a laser 2 that outputs in both horizontal directions of the substrate, and an output waveguide 3 for signal light and an output waveguide 4 for alignment light are provided at both ends thereof. The alignment light output waveguide 4 is configured to bend the alignment light propagation direction in the same direction as the signal light, and the optical path conversion mirrors 3a and 4a are provided ahead of the signal light and alignment light output waveguides. Are provided to constitute an optical transmitter.

Although it is not always necessary to bend the output waveguide 4 of the alignment light in the same direction as the signal light, it is desirable to dispose the mirror on the same side of the substrate as much as possible in order to reduce the processing time of the mirror. In this case, so as to correspond to the reflective surface of the mirror made by one processing,
The propagation direction of the alignment light is propagated in the same direction as that of the signal light by the bending waveguide, and the mirror positions are aligned.

  By driving current to the laser 2 from an electrode (not shown), signal light and alignment light are emitted above the substrate 1 via the mirrors 3a and 4a, and via corresponding mirrors 3b and 4b formed on the PLC 5, Coupled to the quartz waveguides 3c and 4c of the PLC 5 with high efficiency, output from the signal light port 3d and the alignment light port 4d at the left end of the PLC, and monitored for alignment as an optical transmitter.

  In the description of the PLC 5 in FIG. 1, it is noted that the waveguides 3 c and 4 c and the mirror portions 3 a and 4 a are structures formed on the back side of the silicon substrate, as can be seen from the dotted lines.

  When the laser is driven, light that is output backward as an output of the signal light in the reverse direction and is not normally used is used as alignment light, so that only one laser is driven, and the signal light and alignment light are transmitted to the PLC. It is possible to monitor the intensity of light to be combined and perform alignment with high accuracy. Therefore, since it is possible to perform high-precision alignment without producing an extra laser for alignment light and only by driving one laser, the structure of the integrated laser can be simplified and mounted easily. Can do.

  As described above, the present invention includes a laser, a signal light waveguide and a mirror, and a mirror having the same mirror angle formed simultaneously with the alignment light waveguide and the signal light side mirror on the rear output side of the laser. The most characteristic feature is that the signal light and the alignment light are simultaneously output by driving the laser.

  At this time, assuming, for example, a PLC 5 in which a multiplexer and a mirror are integrated as a waveguide platform to be stacked, two beams incident on the PLC 5 from the laser substrate 1 are converted into a signal light port 3d and an alignment port of the PLC 5, respectively. By measuring the light intensity when it is output from 4d and aligning it with the maximum position, the laser substrate 1 and the PLC 5 can be aligned.

  When there is only one output of alignment light, only two optical coupling parts can be monitored together with the signal light, so the inclination of the laser chip substrate surface cannot be determined, and the substrate surface of the PLC is used as a reference. Although alignment of the tilt direction of the laser chip is difficult, as shown in Example 2 to be described later, the alignment light waveguide is branched in the middle, two or more alignment light outputs are provided, and combined with the signal light output, If the outputs of three or more optical coupling portions are monitored, the positional relationship of the optical coupling portions corresponding to the monitored output light is arranged at a position where at least three are not in a straight line. Since the surface can be defined by at least three points, the tilt can be easily corrected. As a result, the coupling efficiency can be further improved and simple alignment can be achieved.

  In this way, when stacking a laser and PLC by optical coupling using a mirror, the rear output of the laser is used as alignment light, and only one laser is driven to output signal light and alignment light. By monitoring the intensity of light coupled to the PLC and aligning them to the maximum value, alignment can be performed with high accuracy and simplicity.

  In the conventional optical transmitter, since there is no alignment light, the light intensity of the combined signal light is monitored via the multiplexer, and it is better to finely move it in any direction such as the rotation direction. It is difficult to judge whether or not the alignment is complicated. In addition, by integrating alignment light lasers, high-precision alignment can be achieved, but not only a separate laser that does not carry signals is required, but it is necessary to drive two or more lasers. There is a problem that the mounting structure such as wiring for driving the laser becomes complicated.

  On the other hand, in the present invention, an integrated optical device can be mounted and provided with a simple configuration and simple alignment by using the rear output of the laser as alignment light.

(Example 2)
FIG. 2 shows the structure of the laser substrate 20 constituting the optical transmitter according to the second embodiment of the present invention.

  In this embodiment, on the substrate 20, four DFB lasers 21 to 24 as a laser array chip in order from the top, four corresponding signal light waveguides, and one of the four lasers (for example, DFB laser 21). ) Of the alignment light including the bending structure connected to the rear output of the MMI type 1 × 2 branch circuit 26 provided in the middle of the alignment light waveguide, and provided at the end of each waveguide. Optical path conversion mirrors 21a to 26a are configured.

  The number of branches of the alignment light waveguide may be three or more. However, in order to reliably align the laser chip in the tilt direction, the branched alignment light mirrors (in this case, 25a and 26a) In addition, there are at least three or more optical coupling portions together with the signal light mirror (here 21a), and at least three of them need to be arranged at positions that are not in a straight line.

  The chip size was 2.0 × 2.5 mm, and the resonance length of the DFB laser was 400 μm.

(Partial sectional view of laser substrate)
3 is a partial cross-sectional view of the laser-to-optical coupling portion of the semiconductor chip substrate 20 in FIG. 2 in which the DFB laser 31, the optical waveguide 32, and the mirror 33 are formed (for example, corresponding to the mirror 21a from the DFB laser 21 in FIG. 2). Sectional drawing of the part to do) is shown.

  The layer structure of the DFB laser 31 (21) is as follows: n electrode 31a, n-InP substrate 31b, n-InP clad layer 31c, DFB laser active layer 31d, DFB laser guide layer 31e, p-InP clad layer 31f. A p-electrode 31g of the laser is formed. A diffraction grating is formed on the guide layer by EB (electron beam) drawing.

  The layer structure of the waveguide and mirror part is, from the bottom, an n electrode, an n-InP substrate, an n-InP clad layer, a waveguide core layer 32a, and non-doped InP.

  In the central part of the laser (the part surrounded by the dotted line in FIG. 3), in order to realize a single mode of the oscillation wavelength, a quarter wavelength (λ / 4) A shift is provided.

  In one semiconductor chip, the composition of the active layer is the same, and the wavelength is changed by changing the pitch of the diffraction grating. For example, the oscillation wavelengths of the DFB lasers 21 to 24 are designed to be center wavelengths in the following ranges, respectively, but the present invention is not limited to these wavelengths.

DFB laser 21: 1294.53-1296.59 nm,
DFB laser 22: 1299.02-1301.09 nm,
DFB laser 23: 1303.54-1305.63 nm,
DFB laser 24: 1308.009-130.19 nm.

  The process for manufacturing the above structure uses an initial substrate on which an n-InP clad layer 31c, an active layer 31d of a DFB laser, and a guide layer 31e of a DFB laser are grown on an n-InP substrate 31b. First, after forming a diffraction grating on the substrate surface, the diffraction grating is embedded by regrowth to form a p-InP cladding layer 31f. Next, a mesa structure is formed by etching, and a semi-insulating InP layer doped with Fe is formed on both sides of the mesa by burying regrowth again, so that the InP layer is formed on both sides of the mesa as viewed in the horizontal direction of the resonator. It has a buried heterostructure formed. Subsequently, both ends of the resonator were etched, and the core layer 32a of the waveguide and non-doped InP were buried and regrown. Finally, after forming the n-side and p-side electrodes 31a and 31g, the buried regrowth non-doped InP region is etched at an angle of 45 degrees with respect to the substrate to form an optical coupling portion with the PLC. A mirror 33 (21a) was formed.

(PLC configuration)
FIG. 4 shows a configuration of a PLC 40 that is a multiplexing optical circuit corresponding to the substrate configuration of the optical transmitter of FIG.
Note that in the description of the PLC in FIG. 4 and the next FIG. 6, the waveguide and the optical circuit are structures formed on the back side of the silicon substrate, as can be seen from the dotted lines.

  The PLC 40 shown in FIG. 4 receives four signal lights coming from the optical transmitter substrate 20 shown in FIG. 2 below through the optical path conversion mirrors 41b to 44b as propagation optical circuits and propagates them to the AWG 49. A waveguide, an AWG 49 for multiplexing four input signal lights to one output, and one waveguide for propagating one signal light multiplexed and outputted by the AWG 49 to the signal light port 40d at the chip end ing.

  Further, the PLC 40 of FIG. 4 has two alignment lights at the chip end by inputting two alignment lights from the optical transmitter substrate 20 of FIG. 2 below by the optical path conversion mirrors 45b and 46b as a configuration for alignment. Two alignment light waveguides 45c and 46c propagating to the ports 45d and 46d are also provided.

  A total of three mirrors 41b, 45b, and 46b that receive the signal light and the two alignment lights that are monitored during the alignment are arranged at positions that are not on the same straight line corresponding to the mirrors 21a, 25a, and 26a in FIG. I understand that

(Cross sectional structure of PLC mirror)
FIG. 5 shows a cross-sectional structure of an optical path conversion mirror (for example, 41b) constituting the optical coupling portion of the PLC 40 of FIG.

  In FIG. 5, the signal light and alignment light incident on the PLC 40 from the substrate 20 arrive from the upper side to the lower side as shown by the upper right arrow, and the PLC 40 described as a sketch in FIGS. 4 and 6 is the surface of the substrate. Note that the top and bottom of the are upside down.

  In the process of manufacturing the above structure, firstly, a quartz-based PLC 40 manufactured by an appropriate process is prepared, and an inclined surface of 30 to 60 degrees, for example, 45 degrees, so that the depth becomes deeper than the waveguide by dry etching. (Inclined structure 51) is formed (see, for example, Patent Document 2).

  In addition, although the manufacturing method of an inclined surface does not limit the effect of invention, mirror layout with high precision and a high degree of freedom is attained by manufacturing by dry etching.

  Subsequently, a metal such as gold or aluminum is deposited on the inclined surface by vapor deposition or sputtering to form a reflection film, and the mirror 52 is formed. At this time, the reflective film is formed on the inclined surface by inclining the substrate surface with respect to the vapor deposition source or the sputtering target. The position of the mirror is set in consideration of etching shift or the like so as to correspond to the beam irradiation position from the laser output port.

  An integrated device can be realized by stack mounting the optical transmitter 20 and the PLC 40 described above.

(Example of mounting an optical transmission device according to the second embodiment)
FIG. 6 shows a mounting example of an optical transmission apparatus configured by stack mounting of the substrate 20 and the PLC 40 according to the second embodiment of the present invention. The above optical transmitter and PLC were actually aligned to verify the effect of the present invention.

  First, after roughly aligning the optical coupling portion of the signal light as a center, the laser 21 connected to the alignment light waveguide is driven to output light having a wavelength of about 1.3 μm, while the signal on the PLC end face is output. The light intensity emitted from the optical port 40d and the two alignment optical ports 45d and 46d is monitored through the fibers, and alignment is performed.

  The signal light output of the laser was set to 1 mW, and alignment was performed in the horizontal direction of the chip so that the light intensity of the monitored signal light port 40d was maximized. At this time, alignment light having a light intensity of about 0.1 mW is also output from the two alignment light ports 45d and 46d.

  Subsequently, while monitoring the light intensity of one of the two alignment light output ports in addition to the signal light port 40d, for example, 45d, the horizontal rotation direction of the laser chip surface so that the light intensity of the two ports to be monitored is maximized. Aligned.

  Further, while monitoring the light intensity of the remaining alignment light output port 46d, the alignment was performed in the tilt direction of the chip so that the light intensity of the three ports to be monitored was maximized.

  Finally, the distance between the chips was gradually reduced to adjust the distance between the chips.

  At this time, when the remaining three lasers were driven one by one at an output of 1 mW and the respective losses were evaluated, it was found that the loss due to misalignment was 0.3 dB or less, and high-precision alignment was achieved. As described above, by providing a structure that uses the rear output of the laser as alignment light, it is possible to mount the optical coupling with high efficiency with a simple structure, and a small integrated optical device can be provided.

  In the present invention, an example in which four DFB lasers and an AWG are used as a multiplexer on the PLC has been described, but the number and types of lasers and the number of branches and types of multiplexers are not captured above. Further, an EA modulator integrated DFB laser may be used instead of the (direct modulation) DFB laser. Furthermore, the PLC side is not captured by the AWG as an optical multiplexer, but if it is configured as a PLC, a directional coupler, a Y branch, a Mach Zünder, a dielectric multilayer filter, an MMI, or its Any combination is acceptable.

  As described above, according to the present invention, in stack mounting using a laser mirror without separately providing an alignment laser, alignment for optical coupling between a laser and an optical circuit element such as a PLC is performed. It is possible to provide an optical transmitter and an optical transmission apparatus that can be simply performed and have a simple structure.

1, 20 Substrate 2, 72 Laser 3 Signal optical waveguide 4, 25, 45c, 46c Alignment optical waveguide 3a, 3b, 4a, 4b, 21a-26a, 33, 41b-46b, 52, 72e, 74e Mirror 3c, 4c Quartz Waveguide 3d, 40d Signal optical port 4d, 45d, 46d Alignment optical port 5, 74, 40 PLC
21 to 24, 31 DFB laser 26 MMI branch circuit 31a n electrode 31b n-InP substrate 31c n-InP clad layer 31d, 72a active layer 31e, 72b guide layer 31f p-InP clad layer 31g p electrode 32 waveguide 32a, 53, 74b Waveguide core 49 AWG
51 Inclined Structure 74a Overclad 74c Underclad 73 Solder

Claims (4)

An optical transmitter provided with at least one laser on a substrate,
An output waveguide for signal light and an output waveguide for alignment light are provided at both ends of at least one of the lasers,
Mirrors for optically converting the signal light and the alignment light are respectively provided at the tip of the output waveguide of the signal light and the alignment light .
The output waveguides before SL signal light or the alignment light, the propagation direction of the alignment light and the signal light and waveguide bend in the same direction is provided in the substrate surface,
The output waveguide of the alignment light is provided with a structure that branches the alignment light into two or more before the optical path conversion,
A mirror that converts the optical path is also provided at the tip of the output waveguide of the branched alignment light,
When the angle formed by the substrate surface and the reflecting surface of the mirror is the mirror angle, the mirror angle is between 30 degrees and 60 degrees,
At least three or more of the mirrors that change the optical path together with one of the signal lights are provided,
An optical transmitter characterized in that at least three of the mirrors are formed at positions that are not in a straight line . The optical transmitter according to claim 1 ,
An optical transmitter characterized in that each mirror is formed at the same mirror angle. The optical transmitter according to claim 1 or 2 ,
Two or more lasers are provided on the substrate;
Each of the lasers is provided with an output waveguide of signal light, and an optical path conversion mirror,
A structure in which one or more of the lasers is provided with an output waveguide for alignment light including a bending structure, the alignment light is bent in the propagation direction of signal light, and the optical path is converted by a mirror provided at the tip of the output waveguide. An optical transmitter characterized in that is provided. An optical transmitter in which the optical transmitter according to any one of claims 1 to 3 is mounted on a PLC,
The PLC includes
A first optical path conversion mirror for converting the optical path of the signal light from the optical transmitter;
A first waveguide for propagating the signal light whose optical path has been converted by the first optical path conversion mirror;
A second optical path conversion mirror for converting the optical path of the alignment light from the optical transmitter;
A second waveguide for propagating the alignment light whose optical path has been converted by the second optical path conversion mirror;
An optical transmitter characterized by comprising:

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