JP5065230B2 - Optical module and method of manufacturing optical module - Google Patents

Description

  The present invention relates to an optical module configured by connecting two optical devices and a manufacturing method thereof, and more particularly to an optical module connected by aligning a distance between optical devices with high accuracy and a manufacturing method thereof.

Along with the advancement of optical communication, higher functions of optical devices used for this are being promoted. Optical devices include optical active components that receive and emit signal light, and optical passive components that demultiplex / multiplex signal light. These optical devices include other optical devices or optical fibers, etc. A waveguide for optical connection is formed. The optical active component is formed based on a semiconductor material such as a semiconductor laser or a semiconductor photodiode, and a semiconductor waveguide is formed as a waveguide. On the other hand, as an optical passive component, a planar lightwave circuit (PLC) having a waveguide based on a silica-based material (SiO ₂ ) or the like has been commercialized.

  Each of the above optical devices is not only used alone, but an optical module having a higher function by combining two or more optical devices is being developed (for example, Patent Documents 1 and 2). In order to manufacture an optical module, it is necessary to optically connect the waveguides between the two optical devices to be optically connected with high accuracy. Specifically, end faces having input / output ends of a waveguide to be optically connected are opposed to each other, for example, predetermined light is incident from the waveguide of one optical device to the waveguide of the other optical device, and the other optical device The alignment in the direction parallel to the end face can be performed so that the intensity of light incident on the waveguide is maximized.

  Further, a method as shown in FIG. 12 is used in order to perform alignment so that the distance between the opposing end faces has a predetermined size. In this method, first, the end surfaces of the two optical devices 901 and 902 are pressed against each other so that the distance between the end surfaces becomes zero (FIG. 12A). Next, from this state, for example, by using a high-precision automatic stage driven by a stepping motor with a contact sensing function, either one of the optical devices is moved by a predetermined distance, so that a predetermined distance between the opposing end surfaces is determined. (Fig. 12 (b)).

As another method for aligning the distance between the end faces, a method as shown in FIG. 13 is also used. In the method shown in FIG. 13, a microscope 903 having a sufficiently high magnification is placed on top of optical devices 901 and 902 for optical connection, and alignment is performed using this to measure the distance between opposing end faces. .
Japanese Patent Laid-Open No. 10-227936 JP 2002-31731 A

  However, in the conventional method shown in FIG. 12, when the end faces are pressed against each other, a load is applied to each waveguide. When silica-based PLCs having relatively high strength are optically connected, there is a low possibility that the waveguide will be damaged by the load. However, if either one of the optical devices is an optical device with low strength such as an InP-based semiconductor waveguide, for example, there is a possibility that the semiconductor waveguide may be damaged by the load when the end faces are pressed against each other. there were. While the silica-based PLC has a thickness of about 1 mm, the semiconductor waveguide has a thickness as thin as about 0.1 to 0.2 mm, so that the strength is lower than that of the silica-based PLC. Therefore, when the semiconductor waveguide is pressed against the silica-based PLC, the semiconductor waveguide may be damaged.

  Further, in the method using the conventional microscope shown in FIG. 13, it is not necessary to press the two optical devices, so that the problem of damaging the semiconductor waveguide is eliminated. However, when two optical devices having different heights from the upper surface to the waveguide are optically connected (FIG. 13B), the heights of the respective upper surfaces differ when the heights of the waveguides are matched. End up. Therefore, both cannot be focused at the same time, and the distance between the end faces cannot be measured with high accuracy using a microscope.

  In addition, when the refractive indexes are different between the two optical devices, the light emitted from one of the optical devices is incident on the waveguide of the original optical device again after being reflected by the end face of the other optical device. There is a risk of propagation in the opposite direction. In order to prevent this, a method of cutting the end face of the other optical device obliquely is taken. As a method of cutting the end face obliquely, when the upper surface side of the waveguide is cut forward (FIG. 13C), the end face of one optical device is hidden under the upper face protruding forward. It disappears. As a result, there has been a problem that the distance between the end faces cannot be measured with high accuracy using a microscope.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide an optical module in which the distance between the end faces of two or more optical devices is measured with high accuracy and optically connected, and a method for manufacturing the same. And

In order to solve the above problems, a first aspect of the optical module of the present invention is an optical module configured by optically connecting two optical devices at respective connection end faces facing each other. An optical device includes: one connection end face; two directional couplers; a first waveguide having both ends connected to the two directional couplers; the two directional couplers; A first split waveguide and a second split waveguide formed between one connection end face, and a second optical device is formed on the other connection end face and both ends on the other connection end face. A third split waveguide, wherein the one connection end face and the other connection end face are spaced apart by a predetermined distance, between the first split waveguide and the third split waveguide, and the first Optically connected between the two-divided waveguide and the third divided waveguide Is a second waveguide is formed, the first waveguide, the second waveguide and the two directional couplers to form an end face distance measuring optical circuit, the end face distance measuring optical circuit is a Mach-Zehnder - An interferometer (MZI) circuit is formed.

  According to this aspect, the distance between the end faces can be measured with high accuracy using the end face distance measuring optical circuit by forming the end face distance measuring optical circuit across the two optical devices whose connection end faces face each other. An optical module with optical connection can be provided.

  In another aspect of the optical module of the present invention, the first waveguide is connected between terminals at the closest distance between the two directional couplers, and the second waveguide is connected in the two directions. It is characterized in that it is connected between terminals at the farthest distance between the sex couplers. According to this aspect, the first waveguide and the second waveguide can be formed so as not to overlap each other on the first optical device.

  In another aspect of the optical module of the present invention, the first waveguide is connected between terminals at the farthest distance between the two directional couplers, and the second waveguide is in the two directions. The first waveguide and the second waveguide are connected to each other at the closest distance between the sexual couplers, and the first waveguide and the second waveguide are arranged so as not to cause mode coupling. According to this aspect, the radius of curvature of the third divided waveguide on the second optical device can be reduced, and the optical loss can be reduced by reducing the size of the optical circuit for measuring the end face distance. Become.

  Another aspect of the optical module of the present invention is characterized in that the end face distance measuring optical circuit is arranged on one end side in the longitudinal direction of the connection end face. By disposing the end face distance measuring optical circuit and the other optical circuit so as not to overlap each other, the respective waveguides can be easily prevented from interfering with each other.

  In another aspect of the optical module of the present invention, the optical circuit for measuring the end face distance is arranged so as not to cause mode coupling with another optical circuit formed on the two optical devices. It is characterized by. By arranging so that mode coupling does not occur between the waveguides, it becomes possible to place the optical circuit for measuring the end face distance and the waveguide of another optical circuit in an overlapping manner. The degree of freedom can be increased.

  In another aspect of the optical module of the present invention, one of the first divided waveguide and the two directional couplers and the other of the second divided waveguide and the directional coupler are the first light. It is arranged at both ends in the longitudinal direction of the connection end face of the device. According to this aspect, it is possible to increase the degree of freedom of the waveguide layout of another optical circuit by limiting the range in which the end face distance measuring optical circuit and another optical circuit overlap.

Another aspect of the optical module of the present invention is characterized in that one end face distance measuring optical circuit is disposed at each of both end sides in the longitudinal direction of the connection end face. According to this aspect, by disposing the two end face distance measuring optical circuits on both ends of the connection end face, it is possible to measure the distance between the left and right end faces, respectively, and the connection end faces are paralleled with high accuracy. Can be arranged.

Another aspect of the optical module of the present invention, the first waveguide, the first split waveguide, the second split waveguides, and the length of each of said third split waveguide, the distance between the end face The optical path length of the first waveguide and the optical path length of the second waveguide are determined to be equal to each other at a predetermined size. By making the optical path length of the first waveguide equal to the optical path length of the second waveguide when the distance between the end faces is a predetermined size, it is easy to adjust the distance between the end faces to a predetermined size. It becomes.

  In another aspect of the optical module of the present invention, at least one of the two optical devices is a planar lightwave circuit (PLC) in which a waveguide is formed on a silicon substrate. The optical module of the present invention can be applied to an optical module using a PLC.

  In another aspect of the optical module of the present invention, at least one of the two optical devices has a semiconductor waveguide. The optical module of the present invention can be applied to an optical module using a semiconductor chip.

According to a first aspect of the method for producing an optical module of the present invention, one connection end face, two directional couplers, and a first waveguide having both ends connected to the two directional couplers, A first optical device comprising a first divided waveguide and a second divided waveguide formed between each of the two directional couplers and the one connection end face; and another connection end face; An optical module for optically connecting a second optical device having a third divided waveguide having both ends formed on the other connection end face with the one connection end face opposed to the other connection end face In the manufacturing method, the first divided waveguide and the third divided waveguide and the second divided waveguide and the third divided waveguide are optically connected to each other, respectively. Forming a second waveguide, the first waveguide, the second waveguide, and the two directional couplings; In forming the end face distance measuring optical circuit, the end face distance measuring light circuit, Mach-Zehnder - form an interferometer (MZI) circuit, predetermined from the incident terminal provided on one of said two directional couplers Is incident on the other directional coupler, and the output light emitted from the output terminal provided in the other directional coupler is measured by a predetermined measurement means, and the one connection end face is measured based on the measurement result by the measurement means. Alignment is performed so that the distance between the end faces of the other connection end faces has a predetermined size.

  According to this aspect, predetermined light is incident on an end face distance measuring optical circuit formed across two optical devices, the emitted light is measured, and the end face distance is determined based on the measurement result. Thus, the distance between the end faces can be aligned with a predetermined size with high accuracy.

  In another aspect of the method for producing an optical module of the present invention, continuous light having a predetermined wavelength is used as the incident light, and an optical spectrum analyzer (OSA) capable of measuring a free spectral region (FSR) is used as the measurement means. A target value of the FSR when the distance between the end faces becomes a predetermined size is determined in advance, and the distance between the end faces is adjusted so that the FSR value measured by the OSA matches the target value. It is characterized by. The OSR can be used to easily measure the FSR, and the distance between the end faces can be adjusted to a predetermined size by adjusting the FSR to a predetermined value.

In another aspect of the method for producing an optical module of the present invention, the optical path length of the first waveguide and the optical path length of the second waveguide are equal when the distance between the end faces is a predetermined size. The length of each of the first waveguide, the first divided waveguide, the second divided waveguide, and the third divided waveguide is determined, and pulsed light having a predetermined wavelength is used as the incident light, and the measuring means As described above, an output device that generates SHG light and measures the output thereof is used, and the distance between the end faces is adjusted so that the output of the SHG light is maximized. According to this aspect, the distance between the end faces can be adjusted to a predetermined size by adjusting so that the SHG light has the maximum output.

  According to the present invention, there is provided an optical module in which the distance between end faces is measured with high accuracy by forming an end face distance measuring optical circuit on two or more optical devices to be optically connected, and a method for manufacturing the same. can do.

(First embodiment)
An optical module and an optical module manufacturing method according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. Each component having the same function is denoted by the same reference numeral for simplification of illustration and description.

  When an optical module is manufactured by connecting two or more optical devices at their opposing end faces, it is necessary to measure and align the distance between the connecting end faces (hereinafter referred to as the end face distance) with high accuracy. The optical module of the present invention is configured such that a Mach-Zehnder-interferometer (MZI) circuit is formed across two optical devices to be connected in order to measure the distance between the end faces with high accuracy. The optical module manufacturing method of the present invention uses an optical method in which predetermined light is input from one end of the MZI circuit and light output from the other end is measured, depending on the distance between optical devices. The distance is measured by reading the amount of phase change of the MZI circuit that changes. By using such an optical measurement method, it is possible to measure the distance between the connecting end faces with high accuracy.

Below, the optical module which consists of two optical devices of this invention is demonstrated. Further, although the case where a PLC is used as an optical device will be described as an example, the present invention is not limited to the PLC, and can be applied to a case where a semiconductor waveguide is used, for example. The material constituting the PLC is not limited to silica (SiO ₂ ), and LiNbO ₃ , Si, InP, or the like can also be used.

  An optical module and a manufacturing method thereof according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing a basic structure of an optical module 100 of the present embodiment. The optical module 100 is configured by connecting two PLCs, a first PLC 110 and a second PLC 120. An MZI circuit 101 is formed across the first PLC 110 and the second PLC 120. In the first PLC 110 and the second PLC 120, an original circuit having a predetermined function is formed in addition to the MZI circuit 101, but only the MZI circuit 101 is shown here for simplicity.

  Part of the MZI circuit 101 is formed in the second PLC 120, and the other part is formed in the first PLC 110. In the first PLC 110, a first waveguide 102, a first divided waveguide 103a, and a second divided waveguide 103b are formed as waveguides, and in the second PLC 120, a third divided waveguide 103c is formed. The first waveguide 102 is connected between the terminals 111b and 112a that are closest to each other between the two directional couplers 111 and 112, and the first divided waveguide 103a and the second divided waveguide 103b are The directional couplers 111 and 112 are respectively connected to terminals 111a and 112b which are the farthest distances.

In the directional coupler 111, the terminals 111a and 111b are connected to the incident terminal 111c and the termination 111d, respectively. In the directional coupler 112, the terminals 112a and 112b are connected to the termination 112c and the emission terminal 112d, respectively. The length of the first waveguide 102 is a length from the terminal 111b of the directional coupler 111 in the first 1PLC110 to the terminal 112a of the directional coupler 112. The lengths of the first divided waveguide 103a and the second divided waveguide 103b are the lengths from the terminal 111a of the directional coupler 111 and the terminal 112b of the directional coupler 112 to the connection end face 110a , respectively. .

  In the optical module 100 of the present embodiment, the connection end surface 110a of the first PLC 110 and the connection end surface 120a of the second PLC 120 are opposed to each other, and are connected with a predetermined distance D therebetween. The end of the first divided waveguide 103a on the connection end face 110a side and the one end of the third divided waveguide 103c are connected at a distance D, and the end of the second divided waveguide 103b on the connection end face 110a side is connected to the third end. The other end of the divided waveguide 103c is connected with a distance D. Thus, the first divided waveguide 103a, the third divided waveguide 103c, and the second divided waveguide 103b are optically connected to form the second waveguide 103.

  The second waveguide 103 is formed across both the first PLC 110 and the second PLC 120, and forms the MZI circuit 101 together with the first waveguide 102 and the directional couplers 111 and 112 formed only on the first PLC 110 side. is doing. The length of the first waveguide 102 is constant because it is formed only on the first PLC 110 side, whereas the second waveguide 103 has a connection end face in addition to the waveguides formed on the first PLC 110 and the second PLC 120. Since the space between 110a and 120a is also included, the length varies depending on the distance D between the end faces between the connection end faces 110a and 120a. Therefore, the MZI circuit 101 can be used as an end face distance measuring optical circuit, whereby the end face distance D can be measured.

  In the manufacturing method of the optical module of this embodiment, the end face distance D is set to a predetermined size by measuring the end face distance D using the MZI circuit 101. In the connection between the first PLC 110 and the second PLC 120, not only the distance D but also the alignment in the direction parallel to the end face 110a (and 120a) (the width direction and the thickness direction of the PLCs 110 and 120) is necessary. This can be done by adjusting the light intensity to be guided through the second waveguide 103 connected between the first PLC 110 and the second PLC 120 to be maximum.

  When predetermined light is incident on the MZI circuit 101 from the incident terminal 111c, the incident light is branched into the first waveguide 102 and the second waveguide 103 by the directional coupler 111, and the light guided through each is directional. The signals are combined by the coupler 112 and output from the output terminal 112d. A phase difference corresponding to a difference in distance between the first waveguide 102 and the second waveguide 103 is generated between the light guided through the first waveguide 102 and the light guided through the second waveguide 103. Thus, the interference light corresponding to the phase difference is emitted from the emission terminal 112d. By measuring this, the distance difference between them can be known.

  The distance difference measured as described above is obtained by subtracting the length of the first waveguide 102 from the sum of the lengths of the first divided waveguide 103a, the second divided waveguide 103b, and the third divided waveguide 103c. It is equal to a value obtained by adding twice the distance D between the end faces. Since the lengths other than the end face distance D are known, the distance D can be obtained from the measured distance difference.

  Below, the calculation method of the distance D between end surfaces is demonstrated using FIG. FIG. 2 is a schematic configuration diagram illustrating a state in which the light source 130 and the measurement device 140 are connected to the optical module 100 of the present embodiment in order to measure the distance D. Here, it is assumed that continuous light having a wavelength λ is emitted from the light source 130. Further, it is assumed that an optical spectrum analyzer (OSA) is used as the measuring device 140.

ここで、Ｌ_１は第１導波路１０２の長さ、Ｌ_２１は第１分割導波路１０３ａおよび第２分割導波路１０３ｂの合計長さ、Ｌ_２２は第３分割導波路１０３ｃの長さである。 The refractive index of the waveguides 102, 103a, 103b formed in the first PLC 110 is n ₁ , the refractive index of the waveguide 103c formed in the second PLC 120 is n ₂ , and the refractive index between the end faces 110a and 120a is n _0. , The optical path lengths of the first waveguide 102 and the second waveguide 103 (referred to as S ₁ and S ₂ respectively) are given by the following equations.

Here, _{L 1} is the length of the first waveguide _{102, L 21} is the total length of the first split waveguide 103a and the second split waveguide _{103b, L 22} is the length of the third split waveguide 103c .

ここで、ｋ_０は真空中の伝搬定数を示す（ｋ_０＝２π／λ）。 From Expressions (1) and (2), the amount of phase change generated in each of the first waveguide 102 and the second waveguide 103 (referred to as Δφ ₁ and Δφ ₂ respectively) is given by the following expressions.

Here, k ₀ indicates a propagation constant in vacuum (k ₀ = 2π / λ).

If incident light with electric field amplitudes A _in and B _in is incident on the second waveguide 103 and the first waveguide 102, respectively, and emitted light with electric field amplitudes A _out and B _out is emitted from each, the incident light The following equation is established using the transfer function of the MZI circuit 101 between the output light and the emitted light.

ここで、光路長差Ｓ＝Ｓ_１−Ｓ_２としている。 In the present embodiment, light is incident only on the incident terminal 111 c on the second waveguide 103 side, and light is not incident on the first waveguide 102. Therefore, by setting B _in = 0 _in the equation (5), the output light intensity P of the light emitted from the light emitting unit 114 is given by the following equation.

Here, the optical path length difference S = S ₁ −S ₂ .

The output light intensity P shown in Equation (6) shows a change as shown in FIG. Here, the horizontal axis is (π / λ) S, and the vertical axis is the output light intensity P. As shown in FIG. 3, the output light intensity of MZI having an optical path length difference has a periodic dependence on the reciprocal of the wavelength. Here, if the reference wavelength at which the output light intensity reaches a peak is λ ₀ , the reference wavelength λ ₀ is expressed by the following equation from (π / λ ₀ ) S = Nπ.

As a result, a free spectrum range (FSR), which is a wavelength region within one cycle centered on the reference wavelength λ ₀ , can be obtained from an interval between adjacent peak wavelengths, and is given by the following equation.

  The above equation (8) approximately shows the relationship between the FSR obtained from the measurement result by the OSA 140 and the end face distance D which is the distance between the two PLCs 110 and 120. An example of the measurement result of the FSR with respect to the end face distance D is shown in FIG. In the same figure, each measurement point 11 shows the relationship between the actual distance D between the end faces and the FSR obtained from the measurement result of the OSA 140, and the curve 10 shows the relationship of Expression (8). From this, it can be seen that the distance D between the end faces can be estimated from the FSR with high accuracy using Expression (8).

Therefore, when the target value between the end faces distance D was set to D _0, previously seeking FSR target corresponding to the end face distance D ₀ as shown in FIG. 4 (referred to as FSR ₀₎ from equation (8) In addition, the distance D between the end faces can be adjusted so that the FSR obtained from the measurement by the OSA 140 matches FSR ₀ .

Another measuring method for calculating the end face distance D will be described below with reference to FIG. FIG. 5 is a schematic configuration diagram showing a state in which the pulse light source 150 and the measuring device 160 are connected to the optical module 100 of the present embodiment in order to measure the end face distance D. Here, it is assumed that pulsed light having a wavelength λ ₁ is emitted from the pulsed light source 150. The measuring device 160 includes an SHG (Second-Harmonic Generation) waveguide 161, an SPF (Short Pass Filter) 162, a PD (Photodiode) 163, and an output device (oscilloscope or digital voltmeter) 164.

The SHG waveguide 161 has an SHG crystal, and two pulse lights having a phase difference (time difference) are collected from the optical module 100 to generate SHG light. That is, FIG. 5 constitutes SHG autocorrelation. The SHG light emitted from the SHG waveguide 161 has a half wavelength (hereinafter referred to as λ ₂ ) of the wavelength λ ₁ of the pulsed light emitted from the pulse light source 150, and the first waveguide 102. The output of the SHG light changes according to the difference S between the optical path length S1 of the second optical path and the optical path length S2 of the second waveguide 103.

  SHG light output from the SHG waveguide 161 passes through the SPF 162 and is transmitted to the PD 163 where it is converted into an electrical signal. The electrical signal output from the PD 163 is transmitted to the output device 164 and displayed in a predetermined format. An example of the measurement result output to the output device 164 is shown in FIG. FIG. 6 shows an example of a change in SHG light output with respect to the difference S between the optical path lengths S1 and S2.

  As shown in FIG. 6, the output of SHG light has a characteristic that it is maximized when the optical path length S1 of the first waveguide 102 and the optical path length S2 of the second waveguide 103 are equal. Therefore, in the measurement method of the present embodiment, the lengths of the first waveguide 102 and the second waveguide 103 are formed so that the optical path lengths S1 and S2 are equal when the end face distance D is the target size. deep. As a result, the end face distance D can be set to a target size by adjusting the end face distance D so that the output of the SHG light is maximized.

  As described above, according to the optical module and the manufacturing method of the optical module of the present embodiment, an MZI circuit is formed as an end face distance measuring optical circuit on two or more optical devices to be optically connected, and the distance between the end faces is used by using this circuit. Can be measured with high accuracy. By making it possible to measure the distance between the end faces with high accuracy, it is possible to provide an optical module in which the connection end faces are aligned with high precision.

(Second Embodiment)
An optical module according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic configuration diagram showing a basic structure of the optical module 200 of the present embodiment. The optical module 200 of this embodiment is configured by joining PLCs 210 and 220, and an MZI circuit 201 is formed across both PLCs as an end face distance measuring optical circuit, as in the first embodiment. ing.

  In the optical module 200 of the present embodiment, in addition to the MZI circuit 201, the PLCs 210 and 220 are formed with a first circuit 211 and a second circuit 221 having respective predetermined functions. As the first circuit 211 and the second circuit 221, optical circuits such as AWG and splitter are formed. The first circuit 211 and the second circuit 221 are configured to function suitably by being connected by being separated by a predetermined distance D between the end faces.

  In the optical module 200 of the present embodiment, the MZI circuit 201 for measuring the end face distance D is arranged at the left end of the PLCs 210 and 220 so as not to overlap the first circuit 211 and the second circuit 221. Alternatively, the first circuit 211 and the second circuit 221 may be arranged at the right end that does not overlap. In this way, by arranging the MZI circuit 201 so as not to overlap with the first circuit 211 and the second circuit 221, there is no possibility that the respective waveguides interfere with each other. It can be carried out.

(Third embodiment)
An optical module according to a third embodiment of the present invention will be described with reference to FIG. FIG. 8 is a schematic configuration diagram showing a basic structure of the optical module 300 of the present embodiment. The optical module 300 of the present embodiment is configured by joining PLCs 310 and 320, and an MZI circuit 301 is formed across both PLCs as an end face distance measuring optical circuit, as in the first embodiment. ing.

  In the optical module 300 of the present embodiment, the first circuit 311 and / or the second circuit 321 and the MZI circuit 301 formed in the PLCs 310 and 320 are arranged at positions where they overlap. Also in the present embodiment, each of the first circuit 311 and the second circuit 321 is configured to function suitably by being connected with a predetermined distance D between the end faces. Positioning is performed by measuring with high accuracy using the MZI circuit 301 so that the PLCs 310 and 320 are connected at a suitable distance D between the end faces.

  In the present embodiment, since the first circuit 311 and the second circuit 321 and the MZI circuit 301 are arranged to overlap each other, an arrangement is made so that mode coupling does not occur between the respective waveguides. As a method of overlapping so that mode coupling does not occur between the waveguide of the first circuit 311 or the waveguide of the second circuit 321 and the waveguide of the MZI circuit 301, for example, both waveguides are arranged as orthogonal as possible. Is good.

  As described above, the MZI circuit 301 can be arranged so as to overlap the first circuit 311 or the second circuit 221, so that the degree of freedom with respect to the arrangement position of the MZI circuit 301 can be increased. That is, by making it possible to arrange the MZI circuit 301 not only on the left and right ends of the PLCs 310 and 320 but also in the vicinity of the center, the position for measuring the distance D between the end faces can be selected more freely.

(Fourth embodiment)
An optical module according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a schematic configuration diagram showing a basic structure of the optical module 400 of the present embodiment. The optical module 400 of the present embodiment is configured by joining PLCs 410 and 420, and an MZI circuit 401 is formed across both PLCs as an end face distance measuring optical circuit, as in the first embodiment. ing.

  In the optical module 400 of the present embodiment, only a part of the MZI circuit 401 is arranged at a position overlapping the first circuit 415 and the second circuit 425 formed in the PLCs 410 and 420, respectively, and the other part of the MZI circuit 401 is The first circuit 415 and the second circuit 425 are arranged so as not to overlap. Also in this embodiment, each of the first circuit 415 and the second circuit 425 is configured to function suitably by being connected with a predetermined distance D between the end faces. The MZI circuit 401 is used for high-precision measurement and alignment so that the PLCs 410 and 420 are connected at a suitable distance D between the end faces.

  In the present embodiment, the first divided waveguide 403a and the directional coupler 411 formed in the PLC 410, and the second divided waveguide 403b and the directional coupler 412 are respectively connected to the left and right ends of the PLC 410 that do not overlap the first circuit 415. It is arranged at the position. In addition, only the central portion of the first waveguide 402 is disposed at a position overlapping the first circuit 415. In addition, the third divided waveguide 403 c formed in the PLC 420 is arranged at a position where only the central portion thereof overlaps with the second circuit 425.

  In the MZI circuit 401 of this embodiment, the waveguide overlapping the first circuit 415 or the second circuit 425 is limited to only the central portion of the first waveguide 402 and the central portion of the third divided waveguide 403c. This limits the portion where mode coupling may occur between the waveguides. As shown in FIG. 9, the central portion of the first waveguide 402 can be disposed substantially parallel to the connection end surface 410 b, and is substantially orthogonal to the waveguide connecting the first circuit 415 and the second circuit 425. Is easy to arrange. Further, the central portion of the third divided waveguide 403c can also be disposed along the end side of the PLC 420 as shown in FIG. 9, and is disposed so as to be substantially orthogonal to the waveguide of the second circuit 425. It is relatively easy to arrange so that it does not become.

  As described above, in the optical module 400 of this embodiment, the waveguide layout of the first circuit 415 and the second circuit 425 is limited by limiting the range in which the MZI circuit 401 and the first circuit 415 or the second circuit 425 overlap. It is possible to increase the degree of freedom. In addition, by separating the directional couplers 411 and 412 from the left and right ends of the PLC 410, the curvatures of the first waveguide 402 and the third divided waveguide 403c can be reduced and bent gently.

(Fifth embodiment)
An optical module according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a schematic configuration diagram showing a basic structure of the optical module 500 of the present embodiment. The optical module 500 of the present embodiment includes two MZI circuits 501 and 502 as end face distance measuring optical circuits, and each is formed across both of the two PLCs 510 and 520 to be connected.

  In the optical module 500 of the present embodiment, the MZI circuits 501 and 502 are arranged at both left and right ends that do not overlap the first circuit 511 and the second circuit 521 formed in the PLCs 510 and 520, respectively. Also in this embodiment, each of the first circuit 511 and the second circuit 521 is configured to function suitably by being connected with a predetermined distance D between the end faces. Positioning is performed by measuring with high accuracy using the MZI circuits 501 and 502 so that the PLCs 510 and 520 are connected at a suitable distance D between the end faces.

  In this embodiment, two sets of MZI circuits 501 and 502 are arranged on both the left and right sides of the PLCs 510 and 520, respectively, so that the distances D1 and D2 between the left and right end faces can be measured respectively. . This makes the circuit configuration more complex than the optical module 200 of the second embodiment having only one set of MZI circuits, but measures the distances D1 and D2 between the end faces on the left and right sides so that they are equal. Thus, the connection end surfaces of the PLCs 510 and 520 can be arranged in parallel with high accuracy.

(Sixth embodiment)
An optical module according to a sixth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a schematic configuration diagram showing a basic structure of the optical module 600 of the present embodiment. In the optical module 600 of this embodiment, the configuration of the MZI circuit 601 is different from that of each of the above embodiments. The first waveguide 602 formed in the first PLC 610 is connected between the terminals 611a and 612b which are the farthest distance between the directional couplers 611 and 612, and the first split waveguide 603a and the second split waveguide are connected. Waveguide 603b is connected to terminals 611b and 612a, which are at the closest distance between directional couplers 611 and 612, respectively. In the present embodiment, the method of connecting each terminal of the directional couplers 611 and 612 to the first waveguide 602, the first divided waveguide 603a, and the second divided waveguide 603b is opposite to the above embodiment. It has become.

  By connecting the first divided waveguide 603a and the second divided waveguide 603b to the terminals 611b and 112a which are the closest distances between the directional couplers 611 and 612, respectively, the third divided waveguide formed in the second PLC 620 is obtained. The waveguide 603c can be reduced in size by reducing the radius of curvature. As a result, it is possible to reduce the optical loss by reducing the overall size of the MZI circuit 601. In the first PLC 610, there is an overlap between the first waveguide 602 and the first divided waveguide 603a and the second divided waveguide 603b, but mode coupling does not occur between the respective waveguides. For example, it is preferable to arrange both waveguides as orthogonal as possible. The MZI circuit 601 of this embodiment can be applied to any of the second to fifth embodiments.

  Note that the description in this embodiment mode shows an example of an optical module and a manufacturing method thereof according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the optical module and the like in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a schematic block diagram which shows the basic structure of the optical module which concerns on the 1st Embodiment of this invention. It is a schematic block diagram which shows the state which connected the light source and measuring device for measuring the distance between end surfaces. It is a figure which shows an example of the output light intensity measured with the measuring apparatus. It is a figure which shows an example of the measurement result of FSR with respect to the distance between end surfaces. It is a schematic block diagram which shows the state which connected the pulse light source and measuring device for measuring the distance between end surfaces. It is a figure which shows an example of SHG light. It is a schematic block diagram which shows the basic structure of the optical module which concerns on 2nd Embodiment. It is a schematic block diagram which shows the basic structure of the optical module which concerns on 3rd Embodiment. It is a schematic block diagram which shows the basic structure of the optical module which concerns on 4th Embodiment. It is a schematic block diagram which shows the basic structure of the optical module which concerns on 5th Embodiment. It is a schematic block diagram which shows the basic structure of the optical module which concerns on 6th Embodiment. It is the schematic explaining the method of aligning between the conventional end surfaces. It is the schematic explaining another method of aligning between the conventional end surfaces.

Explanation of symbols

100, 200, 300, 400, 500, 600 Optical module 101, 201, 301, 401, 501, 601 MZI circuit 102, 602 First waveguide 103a, 403a, 603a First divided waveguide 103b, 403b, 603b Second Split waveguides 103c, 403c, 603c Third split waveguides 110, 210, 310, 410, 510, 610 First PLC
110a, 120a Connection end face 111, 112, 411, 412, 611, 612 Directional coupler 111a, 111b, 112a, 112b, 611a, 611b, 612a, 612b Terminal 111c, 611c Incoming terminal 111d, 112c, 611d, 612c Termination 112d, 612d Output terminal 120, 220, 320, 420, 520, 620 Second PLC
130 light source 140 OSA
150 Pulsed Light Source 160 Measuring Device 161 SHG Waveguide 162 SPF
163 PD
164 Output device 211, 311, 415, 511 First circuit 221, 321, 425, 521 Second circuit

Claims (13)

An optical module configured by optically connecting two optical devices at opposing connection end faces,
A first optical device comprising: a connecting end face; two directional couplers; a first waveguide having both ends connected to the two directional couplers; and the two directional couplers A first divided waveguide and a second divided waveguide formed between each and the one connection end face,
The second optical device includes another connection end face and a third divided waveguide having both ends formed on the other connection end face,
The one connection end surface and the other connection end surface are arranged apart from each other by a predetermined distance, between the first divided waveguide and the third divided waveguide, and between the second divided waveguide and the third divided waveguide. And a waveguide are optically connected to each other to form a second waveguide,
The first waveguide, the second waveguide, and the two directional couplers form an end face distance measuring optical circuit, and the end face distance measuring optical circuit forms a Mach-Zehnder-interferometer (MZI) circuit. An optical module characterized in that The first waveguide is connected between terminals at a closest distance between the two directional couplers;
The optical module according to claim 1, wherein the second waveguide is connected between terminals that are farthest from each other between the two directional couplers. The first waveguide is connected between terminals at the farthest distance between the two directional couplers;
The second waveguide is connected between terminals at the closest distance between the two directional couplers;
The optical module according to claim 1, wherein the first waveguide and the second waveguide are arranged so as not to cause mode coupling. The optical module according to any one of claims 1 to 3, wherein the end face distance measuring optical circuit is arranged on one end side in a longitudinal direction of the connection end face. 4. The end face distance measuring optical circuit is arranged so as to overlap with another optical circuit formed on the two optical devices so as not to cause mode coupling. The optical module according to claim 1. One of the first divided waveguide and the two directional couplers and the other of the second divided waveguide and the directional coupler are respectively disposed at both ends in the longitudinal direction of the connection end face of the first optical device. The optical module according to claim 1, wherein the optical module is arranged. 4. The optical module according to claim 1, wherein one end face distance measuring optical circuit is disposed at each of both end sides in the longitudinal direction of the connection end face. 5. Said first waveguide, said first split waveguide, the second split waveguide, and the length of each of the third split waveguide, said first waveguide length between the end surface is at a predetermined size The optical module according to claim 1, wherein the optical path length of the second waveguide is determined to be equal to the optical path length of the second waveguide . The optical module according to any one of claims 1 to 8 , wherein at least one of the two optical devices is a planar lightwave circuit (PLC) in which a waveguide is formed on a silicon substrate. The optical module according to any one of claims 1 to 8 , wherein at least one of the two optical devices includes a semiconductor waveguide. One connection end face, two directional couplers, a first waveguide having both ends connected to each of the two directional couplers, each of the two directional couplers, and the one connection end face A first optical device comprising a first divided waveguide and a second divided waveguide formed between,
Another connection end face, and a second optical device including a third divided waveguide having both ends formed on the other connection end face,
An optical module manufacturing method for optically connecting the one connection end face and the other connection end face to face each other,
A second waveguide is formed by optically connecting between the first divided waveguide and the third divided waveguide and between the second divided waveguide and the third divided waveguide. ,
The first waveguide, the second waveguide, and the two directional couplers form an end face distance measuring optical circuit , and the end face distance measuring optical circuit forms a Mach-Zehnder-interferometer (MZI) circuit. ,
Predetermined incident light is incident from an incident terminal provided on one of the two directional couplers, and emitted light emitted from an output terminal provided on the other directional coupler is transmitted by predetermined measuring means. Measure and
A method of manufacturing an optical module, comprising: aligning a distance between end surfaces of the one connection end surface and the other connection end surface to a predetermined size based on a measurement result by the measurement unit. When the continuous light having a predetermined wavelength is used as the incident light and an optical spectrum analyzer (OSA) capable of measuring a free spectral region (FSR) is used as the measuring means, the FSR when the distance between the end faces becomes a predetermined size. 12. The optical module according to claim 11 , wherein a target value is determined in advance, and the distance between the end faces is adjusted so that the value of the FSR measured by the OSA matches the target value. Method. The first waveguide, the first divided waveguide, the first waveguide, and the second waveguide so that an optical path length of the first waveguide is equal to an optical path length of the second waveguide when the distance between the end faces is a predetermined size. An output device that determines the length of each of the two-divided waveguide and the third divided waveguide, uses pulsed light of a predetermined wavelength as the incident light, generates SHG light as the measuring means, and measures its output The method for producing an optical module according to claim 11 , wherein the distance between the end faces is adjusted so that the output of the SHG light is maximized.

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