JP2018004896A - Method for assembling optical component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for assembling an optical component, by which adjustment of the optical axis of an optical component to be disposed on an optical path corresponding to signal light of each polarized light component can be easily performed with high accuracy.SOLUTION: The method for assembling an optical component includes a step of adjusting the optical axis of an optical component disposed on an optical path corresponding to signal light of each polarized light component with respect to a polarized light beam splitter 21 that branches signal light including two polarized light components having polarization directions orthogonal to each other into one polarized light component and the other polarized light component, while introducing adjusting light, which is prepared by synthesizing a first beam and a second beam having polarization directions orthogonal to each other by use of a polarization synthesizer, and detecting the intensity of the adjusting light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical component assembling method.

  Patent Document 1 discloses a technique related to a coherent optical receiver. In an optical receiver such as an optical receiver for coherent communication, an optical signal in which polarization and phase are multiplexed is input via a polarization maintaining fiber, and the polarization beam splitter (PBS) is used according to the polarization. It is demultiplexed. The demultiplexed optical signal is separated according to the phase by, for example, an optical 90-degree hybrid element. The separated optical signal is converted into an electric signal by the light receiving element.

Japanese Patent Laid-Open No. 5-158096

  FIG. 16 schematically shows the configuration of this coherent optical receiver. A coherent optical receiver 200 shown in FIG. 16 includes a polarizing beam splitter 202, a beam splitter 204, a monitor light receiving element 206, two multimode interferors (optical 90-degree hybrid) 211 and 212, and eight (four sets). Signal light receiving element 234, four amplifiers 235, and eight (four sets) coupling capacitors 236.

The coherent light receiving apparatus 200 receives signal light N ₀ having two polarization components having different polarization directions and local light L ₀ . Part of the signal light N ₀ is branched by the beam splitter 208 and input to the monitoring light receiving element 206. The monitoring light receiving element 206 detects the average light intensity of the signal light N ₀ . The remainder of the signal light N ₀ reaches the polarization beam splitter 202 via the variable attenuator 210 and is branched by the polarization beam splitter 202 into one polarization component N ₁ and the other polarization component N ₂ . One polarization component N ₁ is input to one multimode interferometer 211, and the other polarization component N ₂ is input to the other multimode interferometer 212.

The local light L ₀ is branched by the beam splitter 204. One branched local light L ₁ is input to the multimode interferometer 212, and the other local light L ₂ is input to the multimode interferometer 211. The multimode interferometer 211 outputs two pairs of interference light indicating the XI signal component and the XQ signal component by causing the local light L ₂ and the polarization component N ₁ to interfere with each other. The multimode interferometer 212 outputs two pairs of interference light indicating the YI signal component and the YQ signal component by causing the local light L ₁ and the polarization component N ₂ to interfere with each other. These interference lights are converted into current signals by the signal light receiving elements 234. The current signal output from each signal light receiving element 234 is converted into a differential voltage signal by the amplifier 235 and then output to the outside via the coupling capacitor 236.

In the optical receiver 200 shown in FIG. 16, various optical components are arranged on the optical paths of the signal light N ₀ and the polarization components N ₁ and N ₂ . For example, when the optical entrance of the multimode interferometers 211 and 212 is small, a lens for condensing the polarization components N ₁ and N ₂ toward the optical entrance is required. In addition, mirrors for directing the polarization components N ₁ and N ₂ to the multimode interferometers 211 and 212 are arranged as necessary.

When assembling the optical receiver 200 shown in FIG. 16, it is required to arrange these optical components while performing optical axis adjustment with respect to the multimode interferometers 211 and 212. For this purpose, adjustment light simulating the signal light N ₀ is input from the outside, and the optical axes of these optical components are adjusted so that the optical coupling efficiency between the adjustment light and the multimode interference devices 211 and 212 is increased. Can be considered. At that time, it is required to allow the adjustment light to reach the multimode interferometers 211 and 212 via the polarization beam splitter 202. FIG. 17 is a diagram for explaining the concept of polarization. In general, light has an electric field vector E and a magnetic field vector H in the xy plane. The electric field vector E of light traveling in the + z direction can be decomposed into an x component Ex and a y component Ey. That is, the electric field vector E is expressed as the sum (Ex + Ey) of the x component Ex and the y component Ey. Accordingly, when the adjustment light is linearly polarized as shown in FIG. 18, the adjustment light is branched into the x component Ex and the y component Ey in the polarization beam splitter 202, so that the x component Ex is converted into one multimode interference. The y component Ey can be input to the other multimode interferometer 211.

FIG. 19 is a diagram showing an example of such an optical axis adjustment method. As shown in the figure, linearly polarized test light LD is output from the light source 221, and this test light LD is input to the optical receiver 200 via the polarization controller 222. Then, the polarization controller 222 adjusts the light intensity of _one polarization component LD _{1 and} the light intensity of the other polarization component LD ₂ of the test light LD branched by the polarization beam splitter 202 to a desired magnitude. The polarization direction of the test light LD is adjusted. Thereafter, various optical components are arranged on the optical paths of the test light LD and the polarization components LD ₁ and LD ₂ to maximize the optical coupling efficiency between the polarization components LD ₁ and LD ₂ and the multimode interferometers 211 and 212. The optical axes of these optical components are adjusted so that

However, in the above method, if an error occurs in the relative angle around the optical axis between the polarization beam splitter 202 and the polarization direction of the test light LD, the intensity ratio (branch ratio) between the x component Ex and the y component Ey is a predetermined value. The optical coupling efficiency between the polarization components LD ₁ and LD ₂ and the multimode interferometers 211 and 212 cannot be accurately measured because the intensity ratio varies. That is, when each of the polarization components LD ₁ and LD ₂ is measured individually, the measurement of the polarization component LD _{1 and} the measurement of the polarization component LD ₂ are performed by adjusting the polarization in each measurement. ₁ and LD ₂ cannot be measured accurately. Therefore, it is necessary to adjust the relative angle between the polarization beam splitter 202 and the polarization direction of the test light LD with high accuracy in advance, and it takes a long time to assemble the optical receiver 200 and makes it difficult to assemble. .

  The present invention has been made in view of such problems, and is an optical that can easily and accurately adjust the optical axis of an optical component arranged on an optical path corresponding to the signal light of each polarization component. An object is to provide a method for assembling parts.

  In order to solve the above-described problem, an optical component assembling method according to an embodiment of the present invention converts signal light including two polarization components whose polarization directions are orthogonal to each other into one polarization component and the other polarization component. While introducing the adjustment light obtained by combining the first light and the second light whose polarization directions are orthogonal to each other using a polarization beam combiner into the branched polarization beam splitter, while detecting the light intensity of the adjustment light, A step of adjusting an optical axis of an optical component arranged on an optical path corresponding to the signal light of each polarization component.

  According to the method for assembling an optical component according to the present invention, it is possible to easily and accurately adjust the optical axis of the optical component arranged on the optical path corresponding to the signal light of each polarization component.

FIG. 1 is a plan view schematically showing a coherent receiver that is an object of an assembling method according to an embodiment of the present invention. FIG. 2 is a perspective view showing the inside of the coherent receiver shown in FIG. FIG. 3A and FIG. 3B are diagrams for explaining a method of manufacturing a coherent receiver. FIG. 3A shows a state in which a standard mirror having a light reflecting surface and a bottom surface perpendicular to each other is installed. FIG. 3B shows how the standard mirror is replaced with a package on which a base and a VOA carrier are mounted. FIG. 4 is a diagram for explaining a method of manufacturing a coherent receiver, and shows a state in which a monitor PD is mounted on a VOA carrier. FIG. 5 is a perspective view showing a part of a manipulator for holding a simulated port. FIGS. 6A and 6B are block diagrams illustrating a configuration for generating the adjustment light. FIG. 7 is a perspective view showing a configuration example of a polarization beam combiner. FIG. 8 is a diagram for explaining a method of manufacturing a coherent receiver, and illustrates how the reflector is aligned and fixed. FIG. 9 is a diagram for explaining a method of manufacturing a coherent receiver, and illustrates how the first lens is aligned and fixed. FIG. 10 is a diagram for explaining a method of manufacturing a coherent receiver, and illustrates how the second lens is aligned and fixed. FIG. 11 is a diagram for explaining a method of manufacturing a coherent receiver, and illustrates how the Sig light input lens is aligned and fixed. FIG. 12 is a diagram for explaining a method of manufacturing a coherent receiver, and shows a state where a VOA is mounted on a VOA carrier. FIG. 13 is a diagram for explaining a method of manufacturing a coherent receiver and shows a state in which an attenuator is mounted. FIG. 14 is a diagram for explaining a method of manufacturing a coherent receiver, and shows a state in which a lid for closing the casing is attached with a seam seal, and the inside of the casing is hermetically sealed. FIG. 15 is a diagram for explaining a method of manufacturing a coherent receiver, in which a simulated port is replaced with an original Sig optical input port and an Lo optical port, and alignment and fixing of the Sig optical input port and the Lo optical port are performed. It shows a state. FIG. 16 schematically shows the configuration of the coherent optical receiver shown in Patent Document 1. FIG. 17 is a diagram for explaining the concept of polarization. FIG. 18 is a diagram for explaining the concept of polarization. FIG. 19 shows an example of the optical axis adjustment method.

[Description of Embodiment of Present Invention]
First, the contents of the embodiment of the present invention will be listed and described. An optical component assembling method according to an embodiment of the present invention includes a polarization beam splitter that splits signal light including two polarization components whose polarization directions are orthogonal to each other into one polarization component and the other polarization component. While introducing the adjustment light obtained by combining the first light and the second light whose directions are orthogonal to each other using a polarization beam combiner, the light intensity of the adjustment light is detected and the signal light of each polarization component is supported. A step of adjusting an optical axis of an optical component arranged on the optical path.

  In this assembly method, in order to adjust the optical axis of the optical component, the first and second light beams whose polarization directions are orthogonal to each other are synthesized by the polarization beam combiner, and introduced into the polarization beam splitter as adjustment light instead of the signal light. To do. At this time, since the polarization directions of the first and second lights are orthogonal to each other, even if an error occurs in the relative angle between the adjustment light and the polarization beam splitter around the optical axis, the branching ratio is hardly affected. That is, when the relative angle deviates in one direction, the light intensity of one polarization component after branching decreases for the first light and the light intensity of the other polarization component increases, but the second light The light intensity of one polarization component after branching increases and the light intensity of the other polarization component decreases. Therefore, the light intensity of the polarization component of the first light after splitting and the polarization component of the second light is always constant, and the influence of the error of the relative angle around the optical axis between the adjustment light and the polarization beam splitter. Is hardly affected. Therefore, according to the above assembly method, the light intensity of the adjusted light after branching can be accurately set to a predetermined level without adjusting the polarization direction by the polarization controller 222 shown in FIG. It is possible to easily and accurately adjust the optical axis of the optical component arranged on the optical path of each polarization component.

  In the above assembling method, the optical axis adjustment may be performed while simultaneously detecting the light intensities of the first light and the second light by a plurality of light detecting means.

[Details of the embodiment of the present invention]
A specific example of an optical component assembling method according to an embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included. In the following description, the same reference numerals are given to the same elements in the description of the drawings, and redundant descriptions are omitted.

FIG. 1 is a plan view schematically showing a coherent receiver 1 as an optical component that is an object of an assembling method according to an embodiment of the present invention. FIG. 2 is a perspective view showing the inside of the coherent receiver 1 shown in FIG. The coherent receiver 1 is a device that demodulates information included in phase-modulated signal light by causing local light (Local Beam: Lo light) and signal light (Signal Beam: Sig light) to interfere with each other. The demodulated information is converted into an electric signal and output to the outside of the coherent receiver 1. The coherent receiver 1 includes an optical system for local light and signal light, and two multi-mode interference (MMI) 40 and 50. Further, the coherent receiver 1 includes a housing 2 that accommodates these optical systems and the MMIs 40 and 50. The optical system and the MMIs 40 and 50 are mounted on the bottom surface 2 </ b> E of the housing 2 through the base 4. The base 4 is made of an insulating material such as alumina (Al ₂ O ₃ ) or aluminum nitride (AlN). On the bottom surface 2E, circuit boards 46 and 56 for mounting circuits for processing demodulated information are mounted. The two MMIs 40 and 50 are semiconductor MMIs, for example, made of InP. The MMI 40 has a Lo light inlet 41 and a Sig light inlet 42. By causing local light input to the Lo light inlet 41 and signal light input to the Sig light inlet 42 to interfere with each other, the MMI 40 Demodulate light phase information. Similarly, the MMI 50 includes a Lo light inlet 51 and a Sig light inlet 52, and causes local light input to the Lo light inlet 51 to interfere with signal light input to the Sig light inlet 52. Thus, the phase information of the signal light is demodulated. In the present embodiment, the two MMIs 40 and 50 are provided independently of each other, but they may be integrated together.

The housing 2 has a front wall 2A. In the following description, the front wall 2A side is referred to as the front, and the opposite side is referred to as the rear. However, these front / rear are only for description, and do not limit the scope of the present invention. The Lo light input port 5 and the Sig light input port 6 are fixed to the front wall 2A by, for example, laser welding. The Lo light input port 5 is provided with local light L ₀ via a polarization maintaining fiber 35, and the Sig light input port 6 is provided with signal light N ₀ via a single mode fiber 36. Each of the input ports 5 and 6 has a collimate lens, and the local light L ₀ emitted from the polarization maintaining fiber 35 and the single mode fiber 36 and the signal light N ₀ (states emitted from the respective fibers). Then, divergent light) is changed to collimated light and guided into the housing 2.

  The Lo light optical system guides the Lo light provided from the Lo light input port 5 to Lo light inlets 41 and 51 of the MMIs 40 and 50. Specifically, the optical system for Lo light includes a polarizer 11, a beam splitter (BS) 12, a reflector 13, two lens groups 14 and 15, a skew adjusting element 16, and an attenuation. Device 71. Note that the skew adjustment element 16 and the attenuator 71 may be omitted if not necessary.

The polarizer 11 is optically coupled to the Lo light input port 5 and adjusts the polarization direction of the local light L ₀ provided from the Lo light input port 5. The light source of local light L ₀ outputs extremely flat elliptically polarized light. Even if the light source of the local light L ₀ outputs linearly polarized light, the local light input from the Lo light input port 5 depends on the mounting accuracy of the optical components inserted in the optical path from the light source to the coherent receiver 1. L ₀ does not have linear polarization along the desired direction. The polarizer 11 converts the local light L ₀ input from the Lo light input port 5 into linearly polarized light having a desired polarization direction (for example, a direction parallel to the bottom surface 2E).

The BS 12 splits the local light L ₀ output from the polarizer 11 into two branches. The branching ratio is 50:50. One of the branched local lights L ₁ travels straight on the BS 12 toward the MMI 40. The other local light L ₀ has its optical axis converted by 90 ° by the BS 12, and its optical axis is again converted by 90 ° by the reflector 13, and goes to the MMI 50. The BS 12 and the reflector 13 shown in FIGS. 1 and 2 are of a prism type, and an interface between two prisms bonded to each other is a light branching surface or a light reflecting surface. However, the BS 12 and the reflector 13 are not limited to the prism type, and may be a so-called flat plate type BS and reflector.

The lens group 14 is disposed on the optical path between the BS 12 and the MMI 40, and condenses one local light L ₁ branched by the BS 12 at the Lo light inlet 41 of the MMI 40. The lens group 15 is disposed on the optical path between the reflector 13 and the MMI 50, and collects the other local light L ₂ branched by the BS 12 and reflected by the reflector 13 at the Lo light inlet 51 of the MMI 50. The lens groups 14 and 15 include first lenses 14b and 15b disposed relatively close to the MMIs 40 and 50, respectively, and second lenses 14a and 15a disposed relatively apart from the MMIs 40 and 50. In this way, by combining the first lenses 14b and 15b and the second lenses 14a and 15a into a condensing lens, the local light emission L ₁ and L ₂ with respect to the small Lo light inlets 41 and 51 of the MMIs 40 and 50 can be reduced. The optical coupling efficiency can be increased.

The skew adjustment element 16 is disposed on the optical path between the BS 12 and the lens group 14, and is an optical component of the two local light beams L ₁ and L ₂ branched by the BS 12 from the BS 12 to the Lo light inlets 41 and 51. Correct the difference in length. That is, the optical path length of the local light L ₂ is longer than the optical path length of the local light L _{1 by} the length of the optical path from the BS 12 to the reflector 13. The skew adjustment element 16 compensates for this optical path length difference, in other words, the time difference between the local lights L ₁ and L ₂ up to the Lo light entrances 41 and 51. Skew adjustment element 16 is made of silicon, also, and the transmittance of about 99% with respect to the local light L _1, L _2, the station consists of substantially transparent material to the wavelength of the light-emitting L _1, L _2.

  The optical system for Sig light includes a polarization beam splitter (PBS) 21, a reflector 22, two lens groups 23 and 24, a half-wave (λ / 2) plate 25, a skew adjusting element 26, and an attenuator 81. including. Note that the skew adjustment element 26 and the attenuator 81 may be omitted if not necessary.

The PBS 21 is optically coupled to the Sig light input port 6 and branches the two polarization components of the signal light N ₀ provided from the single mode fiber 36 via the Sig light input port 6. The branching ratio is, for example, 50:50. The polarization direction of the signal light N ₀ provided by the single mode fiber 36 is indefinite. The PBS 21 bisects this based on the polarization direction of the signal light N ₀ . For example, the PBS 21 transmits the polarized light component parallel to the bottom surface 2E of the housing 2 in the signal light N ₀ to be the signal light N _1, and reflects the polarized light component perpendicular to the bottom surface 2E to be the signal light N ₂ . .

The signal light N _{1 that} has passed through the PBS 21 passes through the attenuator 81 and the skew adjustment element 26 and is then optically coupled to the Sig light inlet 52 of the MMI 50 by the lens group 23. The skew adjusting element 26 is disposed on the optical path between the PBS 21 and the lens group 23, and optical signals of the two signal lights N ₁ and N ₂ branched by the PBS 21 from the PBS 21 to the Sig light inlets 42 and 52. Correct the difference in length. That is, the optical path length of the signal light N ₂ is longer than the optical path length of the signal light N _{1 by} the optical path length from the PBS 21 to the reflector 22. The skew adjustment element 26 compensates for this optical path length difference, in other words, the time difference between the signal lights N ₁ and N ₂ up to the Sig light inlets 42 and 52. The skew adjustment element 26 is made of the same material as the skew adjustment element 16.

The other signal light N ₂ reflected by the PBS 21 is rotated by 90 ° in polarization direction while passing through the λ / 2 plate 25. The polarizations of the signal lights N ₁ and N ₂ immediately after branching are orthogonal to each other. By passing the lambda / 2 plate 25 for signal light N _2, the polarization direction of the signal light N ₂ is rotated 90 °, the same as the other signal light N _1. The optical axis of the signal light N ₂ is converted by 90 ° by the reflector 22, and is optically coupled to the SIG light inlet 42 of the MMI 40 via the lens group 24. The PBS 21 and the reflector 22 shown in FIGS. 1 and 2 are of a prism type, and an interface between two prisms bonded to each other is a light branching surface or a light reflecting surface. However, the PBS 21 and the reflector 22 are not limited to the prism type, and may be a so-called flat plate type PBS and reflector in which the surface of the transparent flat plate member has a light branching function or a light reflecting function.

The lens group 23 is disposed on the optical path between the PBS 21 and the MMI 50, and condenses one signal light N ₁ branched by the PBS 21 at the Sig light inlet 52 of the MMI 50. The lens group 24 is disposed on the optical path between the reflector 22 and the MMI 40, and collects the other signal light N ₂ branched by the PBS 21 and reflected by the reflector 22 at the Sig light inlet 42 of the MMI 40. The lens groups 23 and 24 include first lenses 23b and 24b disposed relatively close to the MMIs 50 and 40, respectively, and second lenses 23a and 24a disposed relatively apart from the MMIs 50 and 40. In this way, by combining the first lenses 23b and 24b and the second lenses 23a and 24a into a condensing lens, the signal lights N ₁ and N ₂ for the small Sig light inlets 52 and 42 of the MMI 50 and 40 can be obtained. The optical coupling efficiency can be increased.

The MMI 40 includes a multimode interference waveguide (MMI waveguide) and a photodiode (PD) optically coupled to the waveguide. The MMI waveguide is a waveguide formed on, for example, an InP substrate, and causes local light L ₁ input to the Lo light inlet 41 and signal light N ₂ input to the Sig light inlet 42 to interfere with each other. Te, the information contained in the signal light N _2, the station and the phase component matching emission L ₁ phase, the station and separated into a phase and 90 ° out of phase components of the light-emitting L ₁ demodulates. That is, the MMI 40 demodulates two pieces of independent information regarding the signal light N ₂ . Similarly, the MMI 50 includes an MMI waveguide and a PD optically coupled to the waveguide. The MMI waveguide is a waveguide formed on an InP substrate, and causes local light L ₂ input to the Lo light inlet 51 and signal light N ₁ input to the Sig light inlet 52 to interfere with each other, Demodulate two pieces of independent information.

  The housing 2 has a rear wall 2B on the side opposite to the front wall 2A. Moreover, the housing | casing 2 has the feedthrough 61 provided continuously from the two side walls which connect the front wall 2A and the rear wall 2B to the rear wall 2B. The feedthrough 61 of the rear wall 2B is provided with a plurality of signal output terminals 65, and the four independent information demodulated by the MMIs 40 and 50 are subjected to signal processing in the integrated circuits 43 and 53, and then these signal output terminals 65 are provided. To the outside of the coherent receiver 1. Further, two terminals 66 and 67 are provided on the two side walls. Terminals 66 and 67 provide DC or low-frequency signals such as signals for driving the MMIs 40 and 50 and signals for driving the optical components inside the housing 2. The integrated circuits 43 and 53 are mounted on circuit boards 46 and 56 surrounding the MMIs 40 and 50, respectively. Further, on these circuit boards 46 and 56, a resistance element, a capacitance element, and a DC / DC converter as necessary are mounted.

When the optical coupling efficiency of the local light L ₁ with respect to the MMI 40 is larger than the optical coupling efficiency of the signal light N ₂ with respect to the MMI 40, the attenuator 71 is disposed. Similarly, the attenuator 81 is disposed when the optical coupling efficiency of the signal light N ₁ with respect to the MMI 50 is larger than the optical coupling efficiency of the local light L ₂ with respect to the MMI 50. With these attenuators 71 and 81, it becomes possible to set the coupling efficiencies of the local lights L ₂ and L ₁ to the MMIs 40 and 50 and the coupling efficiencies of the signal lights N ₁ and N ₂ to the same extent. Degradation of the information demodulation accuracy at can be suppressed.

The coherent receiver 1 further includes a Sig light input lens 27, a variable optical attenuator (VOA) 31, a BS 32, and a monitor PD 33 on the optical path of the signal light N ₀ between the PBS 21 and the Sig light input port 6. The BS 32 separates the signal light N ₀ input from the Sig light input port 6. Part of the separated signal light N ₀ is incident on the monitor PD 33. The monitor PD 33 generates an electrical signal corresponding to the intensity of the signal light N ₀ .

The VOA 31 attenuates the signal light N ₀ that has passed through the BS 32 as necessary. The degree of attenuation is controlled by an electrical signal from the outside of the coherent receiver 1. For example, when an over-input state is detected based on the electrical signal from the monitor PD 33 described above, the attenuation of the VOA 31 is increased and the intensity of the signal lights N ₁ and N ₂ toward the MMIs 40 and 50 is decreased. To do. The Sig light input lens 27 collimates the signal light N ₀ that has passed through the VOA 31. Note that the VOA 31 is preferably located at the beam waist formed between the condenser lens of the Sig light input port 6 and the Sig light input lens 27. As a result, a sufficiently narrow beam diameter with respect to the opening of the VOA 31 can be secured. In addition, since the signal light N ₀ becomes collimated light by the Sig light input lens 27, high coupling efficiency can be secured in the optical path to the MMIs 40 and 50. BS 32, VOA 31, and monitor PD 33 are fixed on VOA carrier 30 mounted on bottom surface 2 </ b> E of housing 2. The VOA carrier 30 mounts these optical components on two upper and lower surfaces forming a step. Specifically, the BS 32 and the monitor PD 33 are mounted on one surface, and the VOA 31 is mounted on the other surface.

  A method for manufacturing the coherent receiver 1 of the present embodiment having the above configuration will be described. First, the MMIs 40 and 50 are arranged on a plate-like carrier. At this time, the alignment of the MMIs 40 and 50 is performed by visual observation with reference to the mark. Next, the circuit board 46 is arranged on the carrier so as to surround the MMI 40, and the circuit board 56 is arranged on the carrier so as to surround the MMI 50. Subsequently, by mounting the carrier on the bottom surface 2E of the housing 2, the MMI 40, 50, etc. are arranged on the bottom surface 2E (first mounting step). In addition, the VOA carrier 30 is mounted on the bottom surface 2E of the housing 2 together with the carrier. The carrier and the VOA carrier 30 are fixed to the bottom surface 2E using, for example, solder.

  Subsequently, the integrated circuits 43 and 53 are mounted on the circuit boards 46 and 56. The integrated circuits 43 and 53 are mounted using a conductive resin such as silver paste. After the integrated circuits 43 and 53 are mounted, the solvent contained in the conductive resin is vaporized by raising the temperature of the entire housing 2 (˜180 ° C.). Thereafter, the electrode pads on the upper surfaces of the integrated circuits 43 and 53 and the terminals 65 on the rear side of the housing 2 are electrically connected by wiring. By this wiring, the active alignment of each optical component in the subsequent process, that is, the adjustment light is input to the MMI 40, 50, and each light is placed at a position where the output signal intensity of the PD built in the MMI 40, 50 becomes maximum. Parts can be arranged.

  Subsequently, each optical component is mounted in the housing 2. First, Lo light for optical alignment is generated. As shown in FIG. 3A, a standard reflector 94 having a light reflecting surface 94a and a bottom surface 94b perpendicular to each other is prepared. The light reflecting surface 94a simulates the front wall 2A of the housing 2, and the bottom surface 94b simulates the bottom surface of the housing 2. The standard reflector 94 is composed of a rectangular parallelepiped glass block, for example. Then, the standard reflector 94 is installed on a stage 93 fixed on a support table 95 of the alignment device. At this time, the bottom surface 94b and the stage 93 are brought into close contact with each other.

  The optical axis direction of the autocollimator 125 is aligned with the optical axis direction of the standard reflector 94. Specifically, the visible laser beam L is output from the autocollimator 125, and the laser beam L is applied to the light reflecting surface 94a. Then, the light intensity of the visible laser beam L reflected by the light reflecting surface 94a is detected on the autocollimator 125 side. When the visible laser light L before reflection and the visible laser light L after reflection overlap each other, the detected light intensity becomes maximum. By utilizing this, the optical axis direction of the autocollimator 125 is aligned with the normal direction of the light reflecting surface 94a, that is, the optical axis direction of the standard reflector 94. Thereafter, the standard reflector 94 is removed from the stage 93 and replaced with the housing 2 on which the MMIs 40 and 50, the circuit boards 46 and 56, and the VOA carrier 30 are mounted (FIG. 3B). At this time, the bottom surface of the housing 2 is brought into close contact with the stage 93. Since the optical axis of the autocollimator 125 passes through the space above the housing 2, the visible laser light L passes above the housing 2 and is not introduced into the housing 2.

  Subsequently, as shown in FIG. 4, the monitoring PD 33 is mounted on the VOA carrier 30. Further, the PBS 21, the skew adjustment elements 16, 26, the λ / 2 plate 25, the polarizer 11, and the BS 12 are respectively arranged at predetermined positions in the housing 2 (second mounting step). These optical components are optical components that do not perform alignment work, and are fixed after adjusting only the direction of the light incident surface thereof. Specifically, in this step, the angle of the optical component (the angle of the light incident surface) is adjusted using the optical axis of the autocollimator 125 that has already been adjusted. One side of these optical components is used as a reflection surface for the visible laser light L of the autocollimator 125, and the visible laser light L before reflection and the visible laser light L after reflection are overlapped with each other, and the angles (light Adjust the axial direction. This operation is performed on the optical axis of the autocollimator 125, that is, in the space above the housing 2. Then, while maintaining the orientation (or rotating by a predetermined angle as necessary), these optical components are moved onto the adhesive resin provided at each mounting position, and the adhesive resin is cured and fixed. To do.

  Regarding the PBS 21, the skew adjusting elements 16 and 26, and the polarizer 11, since the light incident surface faces the front wall 2 </ b> A side when mounted on the housing 2, the normal direction of the light incident surface and the autocollimator 125 The optical axis direction is adjusted by matching the optical axis, and the optical axis direction is maintained while maintaining the orientation. In addition, with respect to the λ / 2 plate 25 and the monitor PD 33, the light incident surface faces sideways when mounted on the housing 2, so that the normal direction of the light incident surface and the optical axis of the autocollimator 125 are After adjusting the optical axis direction by making them coincide with each other, it is mounted after rotating by 90 ° around the normal line of the bottom surface 2E. As for the BS 12, the light incident surface faces sideways when mounted on the housing 2, but the light exit surface faces rearward, so the normal direction of the light exit surface or the surface opposite to the light exit surface And the optical axis direction of the autocollimator 125 are made to coincide with each other, and then the optical axis direction is adjusted and then mounted in the housing 2 while maintaining the direction.

  Subsequently, the Sig light input lens 27 and the reflectors 13 and 22 that require alignment because the optical coupling tolerance for the MMI 40 and 50 is smaller than that of the above-described optical components. , And the lens groups 14, 15, 23, 24 are mounted in the housing 2. As a preparation, two simulated ports are arranged on the front wall 2A of the housing 2. These simulated ports simulate the Sig optical input port 6 and the Lo optical input port 5, respectively. From these simulated ports, adjustment light used for alignment of the other optical component is input. Hereinafter, details of the process of preparing the adjustment light will be described.

  FIG. 5 is a perspective view showing a part of the manipulator 90 for holding the simulated port. The manipulator 90 can freely adjust its position and angle (specifically, the position in each direction of three axes (X, Y, Z axes) orthogonal to each other and the angle around two axes perpendicular to the optical axis direction of the simulated port). And an arm 91 that can be changed to the above, and a head 92 provided at the tip of the arm 91. One simulated port is held on the head 92 and disposed at a position where the Sig optical input port 6 is to be attached. The other simulated ports are also held in the same manner as the one simulated port by another manipulator 90, and are arranged at a position where the Lo light input port 5 is to be attached.

FIG. 6A is a block diagram illustrating a configuration for generating adjustment light. In this configuration, the first light LS ₁ and the second light LS ₂ having different polarization directions are combined using the polarization beam combiner (polarization beam combiner) 113. Specifically, by applying a bias voltage to the bias power supply 111a is output to the light source 112a (for example, a semiconductor laser), to generate a first light LS ₁ of the linearly polarized light. Further, given a bias voltage bias power supply 111b is outputted to the light source 112b (for example, a semiconductor laser), to generate a second light LS ₂ linearly polarized light. Then, the first light LS ₁ and the second light LS ₂ are adjusted so that their polarization directions are orthogonal to each other, and then input to the polarization beam combiner 113. The light sources 112a and 112b and the polarization beam combiner 113 are connected by a polarization maintaining fiber. The wavelength of the light LS _{1 and} the wavelength of the light LS ₂ may be the same or different. When the wavelengths of the light LS ₁ and LS ₂ are equal to each other, a single adjustment light is generated using one bias power source and one single wavelength light source, and the adjustment light is bifurcated into one light LS ₁ . The other polarization direction may be rotated by 90 ° to obtain the light LS ₂ .

Here, FIG. 7 is a perspective view showing a configuration example of the polarization beam combiner 113. As shown in FIG. 7, the polarization beam combiner 113 has a configuration in which two polarization maintaining fibers are coupled at the center, and has two input ends 113a and 113b and one output end 113c. The two input ends 113a and 113b are one end surfaces of the two polarization maintaining fibers, the first light LS ₁ is input to _one input end 113a, and the second light is input to the other input end 113b. LS ₂ is input. These lights LS ₁ and LS ₂ proceed to the central portion of the polarization beam combiner 113 while maintaining their polarization directions, and are combined with each other at the central portion. The combined adjustment light LS ₃ becomes light having two different polarization planes, and is output from the output end 113c while maintaining the polarization direction. In FIG. 7, as an example, the polarization direction of the first light LS ₁ is along the slow axis direction of the polarization maintaining fiber, and the polarization direction of the second light LS ₂ is in the fast axis direction of the polarization maintaining fiber. The case where it is along is shown.

Thereafter, the adjustment light LS ₃ reaches the connector 116 via the optical coupler 114. The connector 116 is selectively connected to one of the connectors 117 and 118. A simulated port 123a that simulates the Sig optical input port 6 is optically coupled to the connector 117, and an optical power meter 119 is optically coupled to the other connector 118. A power meter 115 is connected to the optical coupler 114. FIG. 6A shows a system including two power meters 115 and 119, but one power meter may be used as the power meters 115 and 119. The same configuration as described above is also prepared for the simulated port 123b that simulates the Lo light input port 5.

First, the optical connector 116 and the optical connector 118 are connected. Then, the intensity of the adjustment light LS ₃ is detected by the power meter 119, and the intensity of the adjustment light LS ₃ , that is, the incident light intensity with respect to the housing 2 is set to a predetermined value by adjusting the bias voltage. Next, the housing 2 is removed from the stage 93 again and replaced with a standard reflector 94. Then, the optical connector 116 and the optical connector 117 are connected, and the simulated ports 123a and 123b are opposed to the light reflecting surface 94a of the standard reflector 94. When emitting the adjustment light LS ₃ in this state, adjusting light LS ₃ is reflected by the light reflecting surface 94a after being emitted from the simulated port 123a, 123b, and enters again simulated port 123a, to 123b. The intensity of the adjustment light LS ₃ is detected by the power meter 115 via the optical coupler 114. By adjusting the optical axis direction of the simulated ports 123a and 123b to maximize the light detection intensity, the optical axis direction of the simulated ports 123a and 123b is matched with the optical axis direction of the standard reflector 94. Thereafter, as shown in FIG. 3B, the standard reflector 94 is removed from the stage 93 and replaced with the housing 2.

In this step, the simulation ports 123a and 123b are further aligned. First, the intensity of the adjustment light LS ₃ that has entered the housing 2 from the simulated port 123 a is detected by a PD built in the MMI 40. Then, the detected adjustment light LS ₃ of intensity larger direction simulated port 123a is moved over the front wall 2A of the housing 2, performs alignment in the plane perpendicular to the optical axis of the simulation port 123a. Similarly, the intensity of the adjustment light LS ₃ incident in the housing 2 from the simulated port 123b is detected by the PD built in the other MMI 50, and the simulated port 123b is moved in the direction in which the light intensity increases. As a result, alignment is performed in a plane perpendicular to the optical axis of the simulated port 123b. The field diameter of the adjustment light LS ₃ is about 300 μm, while the light input ends of the MMIs 40 and 50 are small, for example, a width of several μm and a thickness of 1 μm or less. Therefore, although the intensity of the adjustment light LS ₃ input to the MMIs 40 and 50 is weak, it is possible to obtain a detection signal that can determine the optical axis of the adjustment light LS ₃ .

  The positions of the simulated ports 123a and 123b in the optical axis direction can be determined by bringing the end faces of the simulated ports 123a and 123b into contact with the front wall 2A of the housing 2.

Subsequently, each optical component requiring alignment is arranged on the optical path between the simulated ports 123a and 123b and the MMI 40 and 50, and the intensity of the adjustment light LS ₃ detected by the PD built in the MMI 40 and 50 is referred to. Then, these optical components are aligned (third mounting step). Further, these optical components are fixed in the housing 2. In addition, the order of alignment and fixing of these optical components is not restricted to the following description, It can carry out in arbitrary orders.

  In this step, the VOA bias power source 120 and the voltage monitors 121 and 122 are connected to the housing 2 as shown in FIG. The VOA bias power supply 120 applies a bias voltage to the VOA 31 when a VOA 31 described later is installed on the VOA carrier 30. The voltage monitors 121 and 122 monitor voltage signals from the circuit boards 46 and 56, respectively.

  First, BS 32 (see FIGS. 1 and 2) is aligned and fixed. That is, the angle (optical axis direction) of the BS 32 is adjusted using the visible laser light L of the autocollimator 125 passing through the upper space of the housing 2 with the front surface of the BS 32 as a reflection surface. Then, the BS 32 is moved onto the VOA carrier 30 while maintaining the direction of the BS 32. Then, on the VOA carrier 30, the BS 32 is moved along the optical axis of the signal light, and the mounting position of the BS 32 at which the received light intensity of the monitoring PD 33 is maximized is determined. Thereafter, the BS 32 is fixed to the VOA carrier 30 using an adhesive resin.

Next, as shown in FIG. 8, the reflectors 13 and 22 are aligned and fixed. First, using the visible laser light of the autocollimator 125 passing through the upper space of the housing 2 with the front surfaces of the reflectors 13 and 22 as reflection surfaces, the angles (optical axis direction) of the reflectors 13 and 22 are used. Adjust. Then, while maintaining the angle of the reflector 13 and 22, the simulated port 123a, thereby respectively incident each adjustment light LS ₃ from 123b to PBS21, BS12. At this time, each adjustment light LS ₃ is bifurcated by the PBS 21 and BS 12, and one of the branched adjustment lights is reflected by the reflectors 13 and 22 and is incident on the MMI 40 and 50. Detect with built-in PD. Then, while slightly moving the reflectors 13 and 22 in the direction perpendicular to the optical axes of the two simulated ports 123a and 123b, the position where the detection intensity of the built-in PD is maximized is determined. It should be noted that when the reflectors 13 and 22 are aligned, the angle determined by the visible laser beam emitted from the autocollimator 125 is maintained in the subsequent alignment operation. Since the mounting angles of the MMIs 40 and 50 with respect to the housing 2 and the optical axes of the optical input ports 5 and 6 have already been determined, the mounting angles of the reflectors 13 and 22 that convert the optical axes by 90 ° are changed. This is because the alignment state that has already been performed is upset.

Subsequently, the four lens groups 14, 15, 23, and 24 are aligned and fixed. First, as shown in FIG. 9, the first lenses 14b, 15b, 23b, and 24b (that is, lenses closer to the MMI 40 and 50) are aligned and fixed. These lenses 14b, 15b, 23b, arranged 24b on predetermined mounting position, incident each adjustment light LS ₃ from the simulated ports 123a, 123b. The adjustment light LS ₃ from the simulated port 123a is branched into two by the PBS 21, and is input to the MMI 50 and 40 through the lenses 23b and 24b, respectively. The adjustment light LS ₃ from the simulated port 123b is bifurcated by the BS 12, passes through the lenses 14b and 15b, and is input to the MMIs 40 and 50, respectively. Thus, the intensity of the adjustment light input to the MMI 40, 50 is detected by the built-in PD of the MMI 40, 50. Then, the position and angle of the lenses 14b, 15b, 23b, and 24b are slightly changed to determine the position and angle at which the light reception intensity of the built-in PD is maximized. After determining the position and angle, the lenses 14b, 15b, 23b, and 24b are fixed using an ultraviolet curable resin. Subsequently, as shown in FIG. 10, the second lenses 14a, 15a, 23a, and 24a are aligned and fixed. These aligning and fixing methods are the same as the aligning and fixing methods of the first lenses 14b, 15b, 23b, and 24b described above.

  Subsequently, as shown in FIG. 11, the Sig light input lens 27 is aligned and fixed. The Sig light input port 6 has a built-in condenser lens, and the focal point of the built-in lens coincides with the focal point of the Sig light input lens 27. Then, by arranging the VOA 31 at the position of the beam waist formed between the built-in lens and the Sig light input lens 27, the signal light can be passed through the shutter having a limited area of the VOA 31, and the extinction ratio of the VOA 31. Can be increased. For the above reason, in place of the simulation port 123a, another simulation port 123c containing a lens having the same focal length as that of the lens built in the Sig light input port 6 is used for alignment of the Sig light input lens 27. Use it. Therefore, in this step, the simulated port 123b is replaced with the simulated port 123c.

Specifically, the standard reflector 94 is installed again on the stage 93 instead of the housing 2, and the connector 116 shown in FIG. 6B is replaced from the simulated port 123b to the simulated port 123c. Then, the simulated port 123c is disposed at a position where the Sig light input port 6 is to be attached using the manipulator 90 shown in FIG. 5 and is made to face the light reflecting surface 94a of the standard reflector 94. In this state, the adjustment light LS ₃ is output from the simulation port 123c, the optical axis position of the simulation port 123c is adjusted to maximize the light intensity detected by the power meter 115, and the simulation port in the optical axis direction of the standard reflector 94 The optical axis direction of 123c is matched. Then, the intensity of the adjustment light LS ₃ that has entered the housing 2 from the simulated port 123c is detected by the PD built in the MMI 50, and the simulated port 123c is moved in a direction in which the received light intensity increases, whereby the simulated port 123c. Alignment is performed in a plane perpendicular to the optical axis. The position of the simulated port 123c in the optical axis direction can be determined by bringing the end surface of the simulated port 123c into contact with the front wall 2A of the housing 2.

Next, the Sig light input lens 27 is moved to the mounting position, the adjustment light LS ₃ provided by the simulation port 123c is incident on the Sig light input lens 27, and the intensity of the adjustment light LS ₃ that has passed through the PD is built in the MMI 50. To detect. Then, the position of the Sig light input lens 27 is slightly changed to determine the position (front-rear direction, left-right direction, and up-down direction) where the light receiving intensity of the built-in PD is maximized. After the determination, the Sig light input lens 27 is fixed using an adhesive resin.

Subsequently, as shown in FIG. 12, the VOA 31 is mounted on the VOA carrier 30. In this step, the VOA 31 is held by the special manipulator 90A, and the VOA 31 is disposed on the optical path of the adjustment light LS ₃ . The manipulator 90A includes two arms 91A that can freely change positions and angles (specifically, positions in three axial directions orthogonal to each other and angles around two axes perpendicular to the optical axis direction of the VOA 31), A head 92A provided at the tip of these arms 91A. The VOA 31 is sandwiched and held by the head 92A. At this time, one head 92A is in electrical contact with one electrode of VOA 31. The other head 92A is in electrical contact with the other electrode of the VOA 31. Then, a bias voltage is applied to the VOA 31 from the VOA bias power source 120 shown in FIG. 6B via the arm 91A and the head 92A.

An ultraviolet curable resin is applied in advance to the VOA carrier 30 with a predetermined thickness (for example, 100 μm or more), and the VOA 31 is held at a predetermined distance (for example, 100 μm) from the surface of the VOA carrier 30. Then, the bias provided from the VOA bias power source 120 is repeatedly applied to the VOA 31 between 0 to 5 V (for example, a cycle of about 1 second). At the same time, the VOA 31 is moved in a direction parallel to the bottom surface 2E of the housing 2 and perpendicular to the optical axis, and the intensity after branching of the adjustment light LS ₃ after attenuation by the VOA 31 is determined by a plurality of built-in PDs in the MMIs 40 To detect.

Thereafter, the VOA 31 is fixed at a position where the difference in attenuation after the branching of the adjustment light LS ₃ is within an allowable range. At this time, since a plurality of built-in PDs can be measured simultaneously, the output difference between the built-in PDs of the MMIs 40 and 50 may be regarded as a difference in attenuation after branching of the adjustment light LS ₃ . When the first light LS ₁ and the second LS ₂ are individually measured, an error occurs in the polarization directions of the first light LS ₁ and the second LS ₂ , so that the orthogonal states of the polarization directions of each other are obtained. It is difficult to adjust while maintaining. In the present embodiment, the first light LS ₁ and the second LS ₂ are adjusted so that the polarization directions of the first light LS ₁ and the second LS ₂ are orthogonal to each other and then input to the polarization beam combiner 113. In contrast, errors in the polarization directions of each other are suppressed. The VOA 31 is mounted at a predetermined angle (for example, 7 °) with respect to the optical axis connecting the condenser lens in the simulation port 123c and the input lens 27. This is because the reflected light does not return to the Sig light input port 6.

  Subsequently, as shown in FIG. 13, attenuators 71 and 81 are mounted. Specifically, similarly to the BS 12 and the PBS 21, the angles of the attenuators 71 and 81 are determined by the visible laser light from the autocollimator 125 above the housing 2. After that, the attenuators 71 and 81 are fixed by placing them on predetermined mounting regions while maintaining the angles and curing the fixing resin.

  Subsequently, as shown in FIG. 14, a lid 2 </ b> C that closes the housing 2 is attached by a seam seal, and the inside of the housing 2 is hermetically sealed. Then, as shown in FIG. 15, the simulated ports 123a and 123b are replaced with the original Sig light input port 6 and Lo light input port 5, and the Sig light input port 6 and Lo light input port 5 are aligned and fixed. Specifically, simulated signal light is introduced from the Sig light input port 6 and the intensity of the signal light is detected by the built-in PD of the MMI 40. Then, the position of the Sig light input port 6 is changed with reference to the intensity of the detected signal light, and the position where the light reception intensity at the built-in PD is maximized is determined. Similarly, for the Lo light input port 5, Lo light is actually introduced and the intensity of the Lo light is detected by the built-in PDs of the MMIs 40 and 50. The position of the Lo light input port 5 is changed while referring to the intensity of the detected Lo light, and the position where the received light intensity at the built-in PD is maximized is determined. After the determination, the Sig light input port 6 and the Lo light input port 5 are fixed to the housing 2. For fixing, YAG welding can be adopted.

The effects obtained by the assembly method according to the present embodiment described above are as follows. In this assembling method, after the MMIs 40 and 50 and the PBS 21 are arranged, the first light LS ₁ and the second light LS ₂ whose polarization directions are orthogonal to each other are adjusted in order to adjust the optical axes of the optical components. 113, and is introduced into the PBS 21 as the adjustment light LS ₃ in place of the signal light N ₀ . At this time, since the polarization directions of the first light LS ₁ and the second light LS ₂ are orthogonal to each other, even if an error occurs in the relative angle between the adjustment light LS ₃ and the PBS 21 around the optical axis, There is almost no effect. This is because the optical axes of the optical components can be adjusted without individually setting the polarization directions of the first light LS ₁ and the second light LS ₂ , so that the first light LS ₁ and the second light after synthesis are combined. the polarization direction of the LS ₂ is because it is rare that an error occurs. Therefore, in the first optical path of the light LS ₁ and the second light LS _2, at the same time it is possible to adjust the optical axis, to set the first light LS ₁ and the second polarization direction of the light LS ₂ individually Compared to times, errors in the polarization directions of the first light LS ₁ and the second light LS ₂ can be suppressed. That is, when the relative angle deviates in a certain direction, the light intensity of one polarization component after branching of the first light LS ₁ decreases and the light intensity of the other polarization component increases, but the second light increases the light intensity of one of the polarization components after branching for LS _2, it decreases the light intensity of the other polarization component. Accordingly, the combined light intensity of the polarization component of the first light LS _{1 and} the polarization component of the second light LS ₂ after branching by the PBS 21 is always constant, and the light intensity around the optical axis between the adjustment light LS ₃ and the PBS 21 is constant. Little affected by relative angle errors. Therefore, according to the assembling method of this embodiment, the light intensity of the adjusted light LS ₃ after branching is accurately set to a predetermined level without adjusting the polarization direction by the polarization controller 222 shown in FIG. Therefore, the optical axis adjustment of the optical component arranged on the optical path of the signal light N ₀ or the polarization components N ₁ and N ₂ can be performed easily and accurately.

DESCRIPTION OF SYMBOLS 1 ... Coherent receiver, 2 ... Housing, 2A ... Front wall, 2B ... Rear wall, 2C ... Lid, 2E ... Bottom, 4 ... Base, 5 ... Lo light input port, 6 ... Sig light input port, 11 ... Polarizer , 12 ... BS, 13, 22 ... reflector, 14, 15, 23, 24 ... lens group, 14a, 15a, 23a, 24a ... second lens, 14b, 15b, 23b, 24b ... first lens, 16, 26 ... Skew adjustment element, 21 ... PBS, 25 ... λ / 2 plate, 27 ... Sig optical input lens, 30 ... VOA carrier, 31 ... VOA, 32 ... BS, 33 ... PD for monitoring, 35 ... Polarization maintaining fiber, 36 Single mode fiber, 40, 50 ... MMI, 41, 51 ... Lo light inlet, 42, 52 ... Sig light inlet, 43, 53 ... Integrated circuit, 46, 56 ... Circuit board, 61 ... Feedthrough, 71 , 81 Attenuator, 111a, 111b ... bias power supply, 112a, 112b ... light source, 113 ... polarization combiner, 113a, 113b ... input end, 113c ... output end, 114 ... optical coupler, 115,119 ... power meter, 116,117 , 118 ... optical connector, 120 ... VOA bias power supply, 121 ... voltage monitor, 123a, 123b, 123c ... simulated port, 125 ... autocollimator, L ₀ ... local light, LD ... adjustment light, LS ₁ ... first light, LS ₂ ... second light, LS ₃ ... adjustment light, N ₀ ... signal light, N ₁ , N ₂ ... polarization components.

Claims (2)

  With respect to a polarization beam splitter that branches signal light including two polarization components whose polarization directions are orthogonal to each other into one polarization component and the other polarization component, the first light and the second light whose polarization directions are orthogonal to each other Optical axis adjustment of optical components arranged on the optical path corresponding to the signal light of each polarization component while detecting the light intensity of the adjustment light while introducing the adjustment light synthesized by using a polarization beam combiner A method for assembling an optical component, including the step of performing the steps.   The optical component assembling method according to claim 1, wherein the optical axis adjustment is performed while simultaneously detecting the light intensities of the first light and the second light by a plurality of light detection means.

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