JP2005134572A - Optical waveguide circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide circuit in which monitor light rays are branched by optical couplers, the branched monitor light rays are received by optical detectors through a reflection plate and signal light rays are passed as they are. <P>SOLUTION: An optical waveguide are branched into monitor optical waveguides 2 and signal light optical waveguides 10 by optical couplers 11. A groove 3, which is formed with a tilt angle θ from the vertical direction with respect to the surface of a substrate 1, is provided for the branched monitor optical waveguides 2 and the signal light optical waveguides 10 so that the groove 3 crosses the optical waveguides 2 and 10. A reflection plate 4, comprising a polyimide film and a gold reflection film, is inserted into the groove 3. The reflection plate 4 reflects monitor light rays branched by the optical couplers 11 toward light receiving sections 6a of photodiodes 6 and the signal light rays are passed as they are. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical waveguide circuit, and more particularly to an optical waveguide circuit using a planar lightwave circuit applicable to an optical communication system.

  In general, optical communication systems such as wavelength division multiplexing (WDM) systems are used because of an increase in communication traffic volume required by the Internet or the like. In such an optical circuit using an optical fiber or an optical waveguide, signal light such as keeping the light intensity of a signal transmitted through the optical waveguide constant or making the light intensity level between channels uniform. There is a need for a device that controls the light intensity of the light to an appropriate value. In such a case, the light intensity of the signal light is monitored in an optical circuit, or the light intensity is controlled based on the monitored result.

  In order to monitor the light intensity of such an optical signal, a method of branching a part of the signal light by providing an optical coupler on the optical waveguide has been conventionally used. However, when such an optical coupler is used, the number of optical components constituting the optical waveguide circuit increases, and the optical components need to be fusion spliced, which complicates the configuration of the optical waveguide circuit. There was a problem.

  On the other hand, a method of monitoring the light intensity by partially reflecting the signal light without using an optical coupler has been proposed (for example, see Patent Documents 1 and 2). The optical device described in Patent Document 1 forms an end face obliquely with respect to the optical axis at a predetermined position of the optical waveguide, and is a part of signal light reflected in a direction different from the optical axis at the end face. A certain reflected light is detected and the light intensity is monitored.

  The optical fiber described in Patent Document 2 forms an end surface perpendicular to the optical axis at a predetermined position of the optical fiber, emits part of the signal light to the outside, and part of the emitted light. Is reflected by another end surface oblique to the optical axis and taken out, and the light intensity is monitored.

  However, when the light intensity is monitored by reflecting a part of the signal light as described in Patent Documents 1 and 2 described above, the reflectance of the signal light on the oblique end surface is the reflected signal light. There is a problem that the correct light intensity cannot be monitored because the value varies depending on the polarization state.

JP-A-6-331837 JP 2000-155235 A JP 2002-182051 A JP 2001-13339 A T. Sawada, et al., “Ultrathin (5 μm) flexible reflective waveplate of fluorinated polyimide and elimination of polarization sensitivity in titanium-diffusedl ithium niobate waveguide circuits,” Jpn.J.Appl.Phys., Vol.37 (1998) pp .6408-6413 T. Hashimoto et al., “Wultichip optical hybrid integration technique with planar lightwave circuit platform,” J. Lightwave technol., Vol. 16, p. 1249, 1998)

  Furthermore, for monitoring the light intensity of signal light, a method has been reported in which a groove is formed obliquely with respect to the optical waveguide and a reflection filter made of a very thin dielectric multilayer film is inserted (for example, see Patent Document 3). .

  FIG. 8 is a block diagram for explaining a conventional optical waveguide circuit. In FIG. 8, reference numeral 41 denotes a substrate (Si), 42 denotes a quartz optical waveguide, 42a denotes a core (optical waveguide for signal light), and 42b denotes a cladding. 43 is a groove for inserting a reflection plate, 44 is a reflection plate (reflection filter), 44a is a polyimide film, 44b is a dielectric multilayer film, 45 is a silicone resin, 46 is a photodiode, 46a is a light receiving portion, and 47 is a subcarrier. Is shown.

  In this optical waveguide circuit, a part of the signal light is reflected upward and received and monitored by the light receiving part 46a of the photodiode 46, and the remaining light can be transmitted as it is. It has the feature that a straight line is sufficient.

  However, when such an isotropic reflector 44 is used, there is a problem that polarization dependency occurs. This is because when the signal light is reflected on an oblique surface, the horizontal polarization component of the substrate 41 is parallel to the reflection surface, whereas the vertical polarization component is the tilt angle of the reflection surface. This is because only θ is different. Therefore, in the optical waveguide circuit shown in FIG. 8, by adjusting the dielectric material of each layer constituting the dielectric multilayer film 44b and the film thickness of each layer, the difference in reflectance of each orthogonal polarization is compensated. And its formation and adjustment is not easy.

  Furthermore, since the angle and reflectance which can be used for the produced reflecting plate 44 are fixed by the dielectric multilayer film 44b, it can be used only with the angle and reflectance initially assumed. Therefore, in order to change the angle of the groove 43 due to the mounting structure or the like, or to change the reflectivity (branch rate to the monitor circuit in the monitor circuit) depending on the use of the optical waveguide circuit, the reflector 44 itself is designed. There was a problem that it was necessary to correct.

  On the other hand, a method of forming a slope by dicing or etching and forming a reflection surface has also been reported (see, for example, Patent Document 4). However, at that time, if the dicing surface or etching surface is not mirrored, loss occurs, or light is scattered and causes stray light, but it is actually difficult to create a mirror surface state. there were.

  The present invention has been made in view of such problems, and an object of the present invention is to divide the monitor light by an optical coupler, and to receive the branched monitor light by a photodetector through a reflector. An object of the present invention is to provide an optical waveguide circuit for monitoring configured to transmit signal light as it is.

  The present invention has been made to achieve such an object. The invention according to claim 1 is directed to an optical waveguide having a monitor optical waveguide and a signal light optical waveguide formed on a substrate, and the optical waveguide. A groove that crosses the waveguide and is formed at a predetermined inclination angle from a direction perpendicular to the surface of the substrate, and transmits the light that is inserted into the groove and propagates to the signal light optical waveguide. It is characterized by comprising a reflecting plate for reflecting the light propagating to the optical waveguide for monitoring, where a part of the light propagating to the waveguide is branched.

  According to a second aspect of the present invention, in the first aspect of the present invention, an optical coupler branching into a monitor optical waveguide and a signal light optical waveguide is provided at a predetermined position of the optical waveguide, and the reflection plate However, the signal light of the signal light waveguide is transmitted and the monitor light of the monitor light waveguide is reflected.

  The invention described in claim 3 is the invention described in claim 1 or 2, characterized in that the optical waveguide is an embedded optical waveguide made of quartz glass.

  According to a fourth aspect of the present invention, in the first, second, or third aspect of the present invention, the reflective plate is a polyimide film patterned with a metal film.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the inclination angle is set to approximately 20 degrees to approximately 50 degrees.

  If a reflector made of a polyimide film deposited with a gold reflective film is used as the reflector, the reflectivity is as good as 95% or more, and even if it is reflected obliquely, the polarization dependence exists in principle regardless of the angle. No (see Non-Patent Document 1, for example).

  For example, an optical monitor circuit can be configured using the gold reflective film as follows. First, an optical coupler for branching the signal light and the monitor light is formed on the optical circuit, and the signal light optical waveguide and the monitor optical waveguide are separated on the optical circuit. Next, a very narrow oblique groove with a width of 20 μm is formed across both of them, and the above-described reflector is inserted and fixed with resin.

  The method of inserting such a reflector into a narrow groove that crosses the optical waveguide and fixing it with a resin is that a half-wave plate is used in the polarization independence of an optical waveguide circuit such as an arrayed waveguide grating (AWG). This is a well-proven method for inserting technology. Here, it is necessary to transmit the signal light and to reflect the monitor light in the direction of the surface of the substrate and to receive and monitor it with a photodiode (PD) element. The polyimide film on which the gold reflective film is deposited can be formed into an arbitrary pattern by etching the gold reflective film, and light can be transmitted with low loss at the place where the gold reflective film is removed.

  Therefore, if the gold reflecting film is removed only by etching at a location corresponding to the signal light optical waveguide, the desired characteristics described above can be obtained, and the amount of light can be monitored only in the monitor optical waveguide.

  Here, with respect to the reflective surface, the surface of the groove is not a mirror surface, and even if there are some irregularities, chips, etc., there is no problem such as scattering because it is filled with a silicone resin having a refractive index almost equal to that of glass. There is no problem in terms of loss because the reflective surface (gold reflective film deposited on the polyimide film) has a reflectance of 95% or more. On the other hand, the portion through which the signal light is transmitted by etching the gold reflecting film can be transmitted with a low loss of 0.2 dB, for example.

  Such a polyimide film has basically the same material and manufacturing process as the half-wave plate used for polarization independence such as AWG as described above. Also, what is actually inserted into the groove by AWG or the like has already been produced and commercialized, and since it is a technology that is actually used, it is easy to manufacture and has high reliability.

  As described above, according to the present invention, the optical waveguide in which the monitoring optical waveguide and the signal light optical waveguide are formed on the substrate, the predetermined inclination from the direction perpendicular to the surface of the substrate and across the optical waveguide. A groove formed at an angle and the light that is inserted into this groove and propagates to the optical waveguide for signal light is transmitted, and a part of the light that propagates to the optical waveguide for signal light is propagated to the branched optical waveguide for monitoring Therefore, the monitor circuit can be configured using only a simple gold reflection film without using a dielectric multilayer film in which the polarization dependence of the reflectance is adjusted. Further, even if the same reflector is used, the branching rate of the optical coupler can be freely determined independently by the design of the optical circuit.

  In addition, since the polarization dependence does not occur even if the angle of the reflecting surface is changed, the angle of the reflecting surface can be freely changed depending on the shape of the photodiode and the mounting form. Furthermore, since the reflectance of the gold reflective film is not affected by the surface roughness, chipping, or shape distortion of the diced groove, the reflectance is good even if the groove dicing conditions are not good until the surface is mirrored. Is obtained.

  Furthermore, it is possible to realize an optical waveguide circuit that can be applied to an inexpensive, small and high performance optical module for monitoring, an optical transceiver, and the like.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 are structural views for explaining an optical waveguide circuit according to a first embodiment of the present invention. FIG. 1 is a plan view, and FIG. 2 is a cross-sectional view taken along the line A-A 'of FIG. In the figure, reference numeral 1 is a substrate (Si), 2 is a quartz-based optical waveguide, 2a is a core (monitoring optical waveguide), 2b is a cladding, 3 is a groove for inserting a reflector, 4 is a reflector (polyimide), 4a Is a polyimide film, 4b is a gold reflective film, 5 is a silicone resin, 6 is a photodiode (PD), 6a is a light receiving portion, 7 is a subcarrier, 8 is a wire bonder, 9 is a subcarrier positioning protrusion, and 10 is signal light. An optical waveguide 11 is an optical coupler.

  In FIG. 1, the optical waveguide circuit according to the first embodiment has eight planar waveguide type (8 channels; ch1 to ch8) optical waveguides formed on a substrate 1, and the optical waveguide is an optical waveguide circuit. They are arranged in parallel to each other at equal intervals from the input section to the light output section, and are branched into the monitoring optical waveguide 2 and the signal light optical waveguide 10 by the optical coupler 11 at a predetermined location. From a direction perpendicular to the surface of the substrate 1, the branched optical waveguide 2 and the signal optical waveguide 10 reach a predetermined position in the substrate 1 across the optical waveguides 2 and 10. Grooves 3 are formed so as to be inclined at a predetermined angle θ.

  A reflective plate 4 made of a polyimide film 4 a and a gold reflective film 4 b is inserted into the groove 3 and filled with a silicone resin 5. A photodiode 6 is arranged on the optical waveguide and above the silicone resin 5 so that the monitor light reflected by the reflecting plate 4 can be received by the light receiving portion 6a. The optical waveguide is preferably a buried optical waveguide made of quartz glass.

  The reflection plate 4 is configured to reflect the monitor light branched by the optical coupler 11 toward the light receiving portion 6a of the photodiode 6 and transmit the signal light as it is. A subcarrier 7 for fixing the photodiode 6 is provided on the silicone resin 5, and the height of the photodiode 6 is determined by the subcarrier 7. Further, a protrusion 9 for positioning the subcarrier 7 is provided so as to contact the surface of the optical waveguide. The photodiode 6 and the subcarrier 7 are connected by a wire bonder 8.

  In this manner, an optical waveguide made of 8-channel quartz glass and having a relative refractive index of 0.75% was formed on the substrate 1 at a pitch of 250 μm. Optical signals are incident on the respective channels from the left side, and the optical coupler 11 branches the light intensity of 10% as monitor light. This branching ratio can be freely changed by design because it is made of an optical waveguide circuit. Then, a groove 3 having a width of 20 μm and a depth of 100 μm is formed by a dicing saw in a direction that crosses all the optical waveguides and is inclined approximately 30 degrees perpendicular to the optical waveguide surface. A reflective plate 4 as shown in FIG. 3 is inserted into the groove 3 and fixed by an optically transparent silicone resin 5.

  Here, the reflecting plate 4 has a thickness of 15 μm, and a gold reflecting film 4 b having a thickness of about 0.5 μm is formed on the surface thereof by sputtering. Thereafter, a location corresponding to the signal light optical waveguide 10 is etched. The gold reflective film was removed. The reflection plate 4 having this thickness can suppress the transmission loss to an extremely low value of 0.2 dB by injecting a resin having a refractive index matched to that of the glass waveguide. Therefore, the monitor light is reflected upward by the reflecting plate 4. On the other hand, signal light is transmitted with low loss.

  Note that FIG. 3 is a configuration diagram of the reflection plate. In this example, only the gold reflective film 4b on the surface is removed so that the polyimide film 4a can be seen from the portion through which the signal light is transmitted. Next, the entire polyimide film 4a is patterned so that the overall shape of the reflector 4 itself is as shown in FIG. 4, that is, the part where the signal light is transmitted is removed from both the gold reflective film 4b and the polyimide film 4a. A may be sufficient. 4 can also be created by a mechanical method in which the gold-deposited reflector 4 is punched out with a mold. In such a case, there is an advantage that reflection existing in FIG. 3 due to a slight difference in refractive index between the polyimide film 4a and glass can be removed.

Hereinafter, the principle of receiving monitor light will be described in more detail.
The gold reflective film 4b obtained by depositing gold on the polyimide film 4a has an excellent reflectance of 95% or more. A planar photodiode 6 having a light receiving diameter of 200 μm is mounted as shown in FIG. 2 so that the reflected light can be received. The photodiode 6 is fixed to the ceramic subcarrier 7 by AuSn solder so that the electrodes can be easily taken out and mounted on the substrate 1. Is taken out via the subcarrier 7.

  Here, the surface of the light receiving portion 6a of the photodiode 6 is fixed at a height of 100 μm so that the reflected light does not spread so much. Here, the height of the photodiode 6 is automatically set to a desired height by using the surface of the substrate 1 as a height reference plane depending on the shape of the subcarrier 7. The shape of the subcarrier 7 itself and the location / shape of the positioning projection 9 may be any convenient shape based on the shape of the device, jig or photodiode 6 used during mounting. Alternatively, another member may be used as the positioning projection 9 or may be made of a curable resin on the substrate 1.

  The horizontal position can be easily fixed with an accuracy within ± 10 μm by using some position reference such as a marker formed on the substrate 1 when fixing the subcarrier 7. This is an operation that can be easily performed with a normal chip mounter. Alternatively, it may be fixed by so-called active alignment in which alignment is performed while monitoring the output current from the photodiode 6.

  On the other hand, the place where the signal light optical waveguide 10 is in contact with the reflecting plate 4 passes through the gold reflecting film 4b by patterning and with low loss. In this way, the light intensity of the 8-channel guided light can be monitored. FIG. 1 shows an example of 8 channels. According to this structure, for example, a monitor circuit having a larger number of channels than 32 channels can be manufactured by inserting the reflector 4 once.

  The distance between the signal light optical waveguide 10 and the monitor optical waveguide 2 was designed to be 250 μm pitch and 500 μm pitch between each channel. This interval can be freely changed by the design of the optical waveguide.

  Moreover, the reflecting plate 4 is equivalent to, for example, a half-wave plate used for polarization independence of the arrayed waveguide grating and has a sufficient record as a product.

  As for the positional accuracy in the groove when the reflecting plate 4 is inserted into the groove 3, it is sufficient that the monitoring optical waveguide 2 has the gold reflecting film 4b, so that ± 50 μm is sufficient. This level of alignment can be easily performed by providing a mark on the reflector 4 and the optical waveguide and observing with a microscope.

  As the light receiving portion 6a for receiving the monitor light, an 8ch photodiode array having a light receiving diameter of 200 μm was used. In this photodiode array, the back surface is fixed to the subcarrier 7 with AuSn solder, and the electrode on each photodiode element is taken out to the electrode on the subcarrier 7 by wire bonding. The alignment method in fixing the photodiode array element to the subcarrier 7 and mounting the subcarrier 7 with the photodiode element on the optical waveguide substrate may use markers formed in each, or the subcarrier 7. An external reference point such as the corner may be used.

  Since this mounting accuracy is ± 10 μm and there is no problem at all, it can be performed with a normal chip mounter. For the convenience of the optical waveguide, for example, when changing the inter-channel distance of the monitoring optical waveguide 2 in order to keep the optical crosstalk between adjacent channels very low, a single photodiode element, not an array, is individually connected to the subcarrier 7. It may be mounted on the top at a desired interval. This operation can also be easily performed by the chip mounter, and after being fixed to the subcarrier 7, it can be handled in a lump like a normal array element.

  As described above, the multi-channel monitor module can be manufactured at a time for the multi-channel by using the array element mounting.

  In such an optical monitor module, the excess loss at the time of transmission of the reflecting plate in the signal light optical waveguide at 1.55 μm was suppressed to an extremely low 0.2 dB. Moreover, the light extracted as the monitor light could be received with almost no loss.

  Furthermore, the circuit configuration of the optical waveguide can be arbitrarily configured and is not limited to the optical waveguide circuit shown in FIG. For example, the optical coupler may be a WDM coupler that branches based on a difference in wavelength. Alternatively, a circuit such as an arrayed waveguide grating (AWG) may be added to the optical input unit side. The optical coupler may not be on the substrate but may be on another substrate. Furthermore, the optical coupler may be configured of an optical fiber type outside the substrate.

  As described above, an example in which the PD array element is resin-sealed has been described. However, the reliability can be further improved by using a PD element or a PD array element that is hermetically sealed by can sealing or the like. In the first embodiment, the groove 3 is tilted approximately 30 degrees from the direction perpendicular to the surface of the substrate 1. However, the tilt angle is approximately 20 depending on the ease of processing the groove and the mounting form. It is possible to prepare within a range of from about 50 degrees to about 50 degrees.

  FIG. 5 is a block diagram for explaining an optical waveguide circuit according to a second embodiment of the present invention, and shows an example used in a three-wavelength transceiver module. In the figure, reference numeral 21 is a substrate (Si), 22 is a quartz-based optical waveguide, 23 is a groove for inserting a reflector (inclined by 40 degrees from the vertical direction), 24 is a reflector (polyimide), and 26 is a photodiode ( PD), 26a is a light receiving part, 31 is a first wavelength filter, 32 is a second wavelength filter, 33 is a laser diode (LD), and 34 is an element mounting part (etching the cladding of the optical waveguide). Yes.

  The outline of this operation is as follows. Optical signals with wavelengths of 1.49 μm and 1.55 μm are input from the station side to the upper left optical input / output unit. Among these, light having a wavelength of 1.55 μm is demultiplexed to the reception port 1 by the first wavelength filter 31. Further, the light having a wavelength of 1.49 μm is demultiplexed to the reception port 2 by the second wavelength filter 32. Here, for the receiving ports 1 and 2, the oblique reflecting plate insertion groove 23 as described in the first embodiment is diced, and the reflecting plate 24 as shown in FIG. The gold reflective film 24b is inserted in part to reflect the monitor light, and only the gold reflective film 24b on the surface is removed from the portion through which the signal light is transmitted so that the polyimide film 4a can be seen.

  On the other hand, a 1.31 μm Fabry-Perot laser element 33 is mounted on the right side by surface mounting and emits 1.31 μm light. The 1.31 μm light is transmitted through the first and second wavelength filters 31 and 32 with low loss and further transmitted through the polyimide reflector 23. With the above configuration, a transceiver that transmits an optical signal having a wavelength of 1.31 μm from the transceiver to the station side and an optical signal having wavelengths of 1.49 μm and 1.55 μm from the station side to the transceiver side is realized. The optical signal speed is 1 Gbit / s for all three wavelengths.

  Here, as the optical waveguide, a quartz glass optical waveguide 22 produced on the substrate 21 with a relative refractive index of 0.45% is used. As the first and second wavelength filters 31 and 32, wavelength filters produced by forming a dielectric multilayer film on a polyimide film, which have been sufficiently proven in conventional optical transceivers or the like, are used. Here, a groove 23 having a width of 20 μm and a depth of 100 μm perpendicular to the optical waveguide surface is formed by dicing, and wavelength filters 31 and 32 having a thickness of 20 μm are inserted into the groove 23. In addition, the surface mount technology used in the conventional optical transceiver or the like is used for mounting the LD 33.

  That is, the gold cladding necessary for fixing the LD 33 to the element mounting portion and taking out the electrode after exposing the end face of the optical waveguide by removing the overclad of the mounting portion of the LD 33 from above with the substrate 21 as an etching stop layer by reactive ion etching. And AuSn layers are patterned. Thereafter, the LD 33 is surface-mounted with AuSn solder with the optical axis aligned by alignment with a marker (see, for example, Non-Patent Document 2).

  FIG. 7 is an enlarged view of the mounting structure of the photodiode for receiving the signal light reflected on the reflector and the upper part, in which the reference numeral 22 is an optical waveguide, 22a is a core, 22b is a cladding, 24a is a polyimide film, Reference numeral 24b denotes a gold reflecting film, 25 denotes a silicone resin, 27 denotes a subcarrier, 28 denotes a wire bonder, and 29 denotes a subcarrier positioning projection. In addition, the same code | symbol is attached | subjected to the component which has the same function as FIG.

  Unlike the optical monitor of the first embodiment, this optical transceiver needs to receive signal light of 1 Gb / s, and the light receiving band is expanded to 2.5 Gb / s using a PD 26 having a light receiving diameter of 80 mm. Incidentally, the light receiving diameter of the PD 26 used in an optical monitor or the like is, for example, 300 mm and the band is about 30 MHz. Thus, when the light receiving diameter is reduced, there is a problem that when the angle of the reflecting plate 24 is approximately 30 degrees as in the first embodiment, the optical axis is shifted due to a slight angle deviation of the reflecting plate 24 and the like and the light receiving sensitivity is deteriorated.

  Therefore, in FIG. 7, the groove 23 for inserting the reflection plate is diced so that the angle θ of the reflection plate 24 is approximately 40 degrees. Thus, as the inclination of the groove 23 from the perpendicular to the substrate surface increases, surface roughness during dicing, chipping at an acute angle portion, and the like increase as shown in FIG. However, since the reflecting plate 24 itself is a reflecting medium, adverse effects such as scattering can be avoided by sealing with resin.

  By increasing the angle of the reflecting plate 24 in this way, the distance from the reflecting plate 24 to the PD 26 can be made closer to prevent the beam from spreading, and the incident angle to the PD 26 becomes closer to the perpendicular so that the beam is more It can be received in a state close to a circle, and can accommodate a PD having a smaller light receiving diameter than that of FIG. The excess loss calculated from the light receiving sensitivity of the PD 26 was about 0.3 dB.

  In the second embodiment, an example is shown in which both 1.49 mm and 1.55 mm signals are received by the reflecting plate 24 by the flip-up surface type PD 26, but various other configurations are possible. For example, the gold reflective film 24b corresponding to the reception port 2 corresponding to 1.49 mm is removed and transmitted, and the reception PD 26 is surface-mounted or guided to the end surface of the substrate 21 by an optical waveguide. It can also be connected to a hermetically sealed PD module of an optical fiber pigtail. Since the reflecting plate 24 uses the patterning of the gold reflecting film 24b, it is arbitrary which of the optical waveguides traversing the reflecting plate 24 reflects the light upward and transmits the light of which optical waveguide. There are features. Therefore, the present invention is not limited to the above-described configuration, and can be applied to an optical waveguide circuit having an arbitrary design and an arbitrary layout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural diagram for explaining a first embodiment of an optical waveguide circuit according to the present invention. FIG. 2 is a sectional view taken along line A-A ′ of FIG. 1. 2 is a configuration diagram of a reflector used in Example 1. FIG. FIG. 6 is another configuration diagram of a reflector used in Example 1. It is a block diagram for demonstrating Example 2 of the optical waveguide circuit which concerns on this invention. 6 is a configuration diagram of a reflector used in Example 2. FIG. It is an enlarged view of the mounting structure of the photodiode for receiving the signal light reflected on the reflecting plate and the upper part. It is a block diagram for demonstrating the conventional optical waveguide circuit.

Explanation of symbols

1,21 Substrate (Si)
2,22 Quartz-based optical waveguides 2a, 22a Cores 2b, 22b Clad 3, 23 Grooves for inserting reflectors 4, 24 Reflector (polyimide)
4a, 24a Polyimide film 4b, 24b Gold reflection film 5, 25 Silicone resin 6, 26 Photodiode (PD)
6a, 26a Light receiving portion 7, 27 Subcarrier 8, 28 Wire bonder 9, 29 Subcarrier positioning protrusion 10 Signal light optical waveguide 11 Optical coupler 31 First wavelength filter 32 Second wavelength filter 33 Laser diode (LD)
34 Element mounting part 41 Substrate (Si)
42 Silica-based optical waveguide 42a Core (optical waveguide for signal light)
42b Cladding 43 Groove 44 for reflection plate reflection plate (reflection filter)
44a Polyimide film 44b Dielectric multilayer film 45 Silicone resin 46 Photodiode 46a Light receiving portion 47 Subcarrier

Claims (5)

  An optical waveguide in which a monitoring optical waveguide and a signal light optical waveguide are formed on a substrate; a groove formed across the optical waveguide and at a predetermined inclination angle from a direction perpendicular to the surface of the substrate; A reflection plate that is inserted into the signal light, transmits light propagating to the optical waveguide for signal light, and reflects light propagating to the optical waveguide for monitoring branched from a part of the light propagating to the optical waveguide for signal light; An optical waveguide circuit comprising:   An optical coupler branching into a monitoring optical waveguide and a signal light optical waveguide is provided at a predetermined position of the optical waveguide, and the reflection plate transmits the signal light of the signal light optical waveguide, and the monitoring optical waveguide The optical waveguide circuit according to claim 1, wherein the monitor light is reflected.   The optical waveguide circuit according to claim 1, wherein the optical waveguide is an embedded optical waveguide made of quartz glass.   4. The optical waveguide circuit according to claim 1, 2, or 3, wherein a polyimide film and a gold reflecting film are used as the reflecting plate. 5. The optical waveguide circuit according to claim 1, wherein the inclination angle is set to approximately 20 degrees to approximately 50 degrees.

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