Optical element and alignment method
The optical element with integrated waveguides and light intensity monitoring units facilitates simultaneous alignment of optical components, addressing inefficiencies in existing alignment methods by reducing alignment and wavelength control times.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NEC CORP
- Filing Date
- 2024-11-29
- Publication Date
- 2026-06-10
AI Technical Summary
Existing methods for aligning optical elements and components in optical modules, such as a light-emitting element and an optical amplifier, are inefficient and time-consuming, particularly when monitoring light intensity to achieve precise alignment.
An optical element with multiple optical waveguides and integrated light intensity monitoring units allows simultaneous alignment of a light-emitting element and an optical amplifier by monitoring reference light intensities, reducing the need for wavelength stabilization and minimizing movement along intersecting directions to achieve precise positioning.
This approach significantly reduces alignment time by half and further reduces wavelength control time by a third, enabling efficient and precise alignment of opposing optical paths.
Smart Images
Figure 2026095176000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to an optical element and an alignment method.
Background Art
[0002] In assembling an optical module or the like, a technique for accurately aligning an optical element and other optical components is used. For example, when configuring a wavelength-variable light source, an operation of aligning a light-emitting element and an optical amplifier with respect to an optical element provided with a wavelength filter is performed.
[0003] For example, in Patent Document 1, a method of aligning a light-emitting element with respect to an optical element while monitoring the intensity of light incident from the light-emitting element by a light-receiving means provided in the optical element has been proposed. In this method, the light intensity is monitored while moving the light-emitting element with respect to the optical element. Then, the light-emitting element is held at a position where the light intensity becomes a sufficiently large value, for example, the maximum value.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005]
[0006] The optical element according to this disclosure includes: a first optical waveguide into which input light is incident; wavelength control means for wavelength filtering the input light guided by the first optical waveguide to output output light of a desired wavelength; a second optical waveguide for guiding the output light; output light intensity monitoring means for monitoring the intensity of the output light guided by the second optical waveguide; a third optical waveguide parallel to the first optical waveguide and spaced apart from the first optical waveguide along a first direction intersecting the direction in which the first optical waveguide extends; a first reference light intensity monitoring means for monitoring the intensity of a first reference light input to the third optical waveguide; and a second optical waveguide spaced apart from the second optical waveguide along a second direction intersecting the direction in which the second optical waveguide extends. The optical waveguide comprises a fourth optical waveguide parallel to the second optical waveguide, and a second reference light intensity monitoring means for monitoring the intensity of a second reference light input to the fourth optical waveguide, wherein the end face into which the input light is incident in the first optical waveguide and the end face into which the first reference light is input in the third optical waveguide belong to a first plane parallel to the first direction and a third direction perpendicular to the first direction and the direction in which the first and third optical waveguides extend, and the end face into which the output light is emitted in the second optical waveguide and the end face into which the second reference light is input in the fourth optical waveguide belong to a second plane parallel to the second direction and a fourth direction perpendicular to the second direction and the direction in which the second and fourth optical waveguides extend.
[0007] The alignment method according to this disclosure includes: a first optical waveguide for guiding input light; wavelength control means for wavelength filtering the input light guided by the first optical waveguide to output output light of a desired wavelength; a second optical waveguide for guiding the output light; output light intensity monitoring means for monitoring the intensity of the output light guided by the second optical waveguide; a third optical waveguide parallel to the first optical waveguide and provided at a distance from the first optical waveguide by a first distance along a first direction intersecting the direction in which the first optical waveguide extends; and input to the third optical waveguide The optical waveguide comprises: a first reference light intensity monitoring means for monitoring the intensity of a first reference light; a fourth optical waveguide parallel to the second optical waveguide, provided at a distance of a second distance along a second direction intersecting the direction in which the second optical waveguide extends; and a second reference light intensity monitoring means for monitoring the intensity of a second reference light input to the fourth optical waveguide, wherein the end face into which the input light is incident in the first optical waveguide and the end face into which light is input in the third optical waveguide are connected to the first direction and the first direction and the first and third optical waveguides The end face from which the output light is emitted in the second optical waveguide and the end face into which the second reference light is input in the fourth optical waveguide belong to a first plane parallel to a third direction perpendicular to the direction in which the path extends, and the end face from which the output light is emitted in the second optical waveguide and the end face into which the second reference light is input in the fourth optical waveguide, and the first alignment for aligning the first element capable of outputting light and the second alignment for aligning the second element capable of outputting light are performed in parallel with respect to the optical elements belonging to a second plane parallel to the second direction and a fourth direction perpendicular to the second direction and the direction in which the second and fourth optical waveguides extend, and in the first alignment, from the first element to the third With the first reference light output to the optical waveguide, the position of the first element relative to the third optical waveguide is adjusted while monitoring the intensity of the first reference light with the first reference light intensity monitoring means, and the first element is held at a position where the intensity of the first reference light falls within a predetermined first range, and the first element is moved by a first distance from the position where the first element is held toward the first optical waveguide along the first direction, and in the second alignment, with the second reference light output from the second element toward the fourth optical waveguide,While monitoring the intensity of the second reference light using the second reference light intensity monitoring means, the position of the second element with respect to the fourth optical waveguide is adjusted, and the second element is held at a position where the intensity of the second reference light falls within a predetermined second range. From the position where the second element is held, the second element is moved by the second distance in the direction toward the second optical waveguide along the second direction. [Effects of the Invention]
[0008] According to this disclosure, the alignment of opposing optical paths can be performed efficiently. [Brief explanation of the drawing]
[0009] [Figure 1] This is a schematic top view showing the configuration of an optical element according to one embodiment. [Figure 2] This is a schematic top view showing the configuration of a tunable light source composed of an optical element and its surrounding components according to one embodiment. [Figure 3] This is a flowchart of the alignment process according to one embodiment. [Figure 4] This diagram schematically shows the arrangement of the optical element, light-emitting element, and optical amplifier at the start of alignment. [Figure 5] This figure shows an example of the alignment process for a light-emitting element and an optical amplifier. [Figure 6] This figure shows an example of adjusting the alignment by moving the light-emitting element and the optical amplifier. [Figure 7] This is a schematic top view showing the configuration of an optical element according to one embodiment. [Figure 8] This is a schematic top view showing the configuration of an optical element according to one embodiment. [Modes for carrying out the invention]
[0010] Embodiments of the present invention will now be described with reference to the drawings. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary.
[0011] When we refer to one embodiment below, it means that it is applicable to any of the embodiments described below, or to a combination of two or more embodiments, and that its application is not limited to a specific embodiment.
[0012] Embodiment 1 The optical element according to this embodiment will now be described. The optical element according to this embodiment is an element having an optical circuit that wavelength filters light input from an external light-emitting element and outputs light of a predetermined wavelength to an external optical amplifier. The optical element according to this embodiment may be configured as a silicon photonics (SiP) element formed on a silicon substrate. Furthermore, the optical element according to this embodiment has a configuration that allows for easy alignment of the external light-emitting element and optical amplifier with respect to the optical waveguide provided in the optical element.
[0013] Figure 1 is a schematic top view showing the configuration of an optical element according to one embodiment. The optical element 100 is an element consisting of an optical circuit formed on a substrate 101. The substrate 101 may be, for example, a silicon substrate. The optical element 100 wavelength filters the input light L1 output from an external light-emitting element. The optical element 100 then outputs output light L2 of a desired wavelength to an external optical amplifier.
[0014] In Figure 1, the X, Y, and Z axes in a three-dimensional Cartesian coordinate system are shown for clarity. In Figure 1, the horizontal direction to the left on the plane of the paper is defined as the X-axis. The normal direction towards the viewer relative to the plane of the paper is defined as the Y-axis. The vertical direction upward on the plane of the paper is defined as the Z-axis. In Figure 1, the end face 110 of the optical element 100 is a plane parallel to the XY plane. The representation of the X, Y, and Z axes in the figures is the same in subsequent figures.
[0015] Figure 2 is a schematic top view showing the configuration of a tunable light source composed of an optical element and its peripheral components according to one embodiment. The tunable light source 1000 has an optical element 100, a light-emitting element 1010, and an optical amplifier 1020. The light-emitting element 1010 and the optical amplifier 1020 may be configured as, for example, semiconductor optical amplifiers. The end faces 1011 and 1012 of the light-emitting element 1010 and the end faces 1021 and 1022 of the optical amplifier 1020 are planes parallel to the XY plane. Hereinafter, the light-emitting element 1010 will also be referred to as the first element. The optical amplifier 1020 will also be referred to as the second element.
[0016] The light-emitting element 1010 is provided with an optical waveguide 1013 extending between end faces 1011 and 1012. An anti-reflective film (not shown) is formed on end face 1011, which is opposite to end face 110 of the optical element 100. A highly reflective film (not shown) is formed on end face 1012, which is opposite to end face 1011. The optical waveguide 1013 is formed to be inclined by a predetermined angle with respect to end face 1011 in order to prevent the influence of reflection of input light L1 at end face 1011. In this example, in the vicinity of end face 1011, the optical waveguide 1013 extends in a direction inclined by φ clockwise with respect to the Z-axis direction, which is the normal direction of end face 1011. A gain region is provided in the optical waveguide 1013. In the light-emitting element 1010, light is emitted by injecting current into the gain region of the optical waveguide 1013, for example, and the input light L1 is guided by the optical waveguide 1013. The input light L1 guided by the optical waveguide 1013 is emitted from the end face 1011 to the optical element 100.
[0017] The optical element 100 includes a wavelength control unit 1, reference light intensity monitoring units 2 and 3, output light intensity monitoring unit 4, and optical waveguides 11-13, 21 and 22. The optical waveguides 11-13, 21 and 22 are formed on a substrate 101. When the optical element 100 is configured as a SiP element, the substrate 101 is configured as a silicon substrate. The optical waveguides 11-13, 22 and 22 are configured as, for example, silicon oxide (SiO2) optical waveguides. The reference light intensity monitoring units 2 and 3 and the output light intensity monitoring unit 4 may include, for example, photodiodes. Hereinafter, optical waveguides 11 and 12 will also be referred to as the first and second optical waveguides, respectively.
[0018] The input light L1 emitted from the light-emitting element 1010 is incident on the optical waveguide 11 through the end face 11A. An antireflection film (not shown) may be formed on the end face 11A. The end face 11A is provided so as to belong to the same plane as the end face 110 of the optical element. Since the optical waveguide 11 guides the input light L1 from the optical waveguide 1013 inclined with respect to the end face 1011 of the light-emitting element 1010, it extends in a direction inclined by φ in the clockwise direction with respect to the normal direction of the end face 11A. Thus, by properly aligning the optical waveguide 1013 of the light-emitting element 1010 and the optical waveguide 11 of the optical element 100, the input light L1 smoothly enters from the optical waveguide 1013 into the optical waveguide 11.
[0019] The input light L1 incident on the optical waveguide 11 enters the wavelength control unit 1. The wavelength control unit 1 wavelength filters the input light L1 and emits the output light L2 having a desired wavelength to the optical waveguide 12. The wavelength control unit 1 may be configured, for example, as a wavelength filter having a general double-ring resonator structure. In this example, by applying a voltage to the electrode provided on the optical waveguide constituting the ring resonator or driving a heater provided near the ring resonator, the effective refractive index of the optical waveguide is adjusted. Thereby, the resonance state of light is controlled, and the wavelength of the oscillating light can be controlled to a desired wavelength.
[0020] Note that the configuration of the wavelength control unit 1 in FIG. 2 is merely an example, and the wavelength control unit 1 may have another configuration as long as it can wavelength filter the input light L1 and emit the output light L2 having a desired wavelength to the optical waveguide 12.
[0021] The optical waveguide 12 is formed so as to be inclined by a predetermined angle with respect to the end face 12A in order to prevent the influence of reflection of the output light L2 at the end face 12A. The end face 12A is provided so as to belong to the same plane as the end face 110 of the optical element. In this example, the optical waveguide 12 extends in a direction inclined by φ in the counterclockwise direction with respect to the normal direction of the end face 12A in the vicinity of the end face 12A. The output light L2 is emitted from the end face 12A to the optical amplifier 1020.
[0022] The optical waveguide 12 is branched between the wavelength control unit 1 and the end face 12A and connected to the optical waveguide 13. A portion of the output light L2 is branched from the optical waveguide 12 to the optical waveguide 13 and incident on the output light intensity monitoring unit 4. The output light intensity monitoring unit 4 receives the incident output light L2. As a result, the output light intensity monitoring unit 4 monitors the intensity of the output light L2.
[0023] The optical amplifier 1020 is provided with an optical waveguide 1023 extending between end faces 1021 and 1022. An anti-reflective coating (not shown) is formed on the end face 1012 facing the end face 110 of the optical element 100. An anti-reflective coating (not shown) is also formed on the end face 1022 opposite to the end face 1021. To prevent the effect of reflection at the end face 1022 of the output light L2 emitted from the optical waveguide 12 of the optical element 100, the optical waveguide 1023 is formed to be inclined by a predetermined angle with respect to the end faces 1021 and 1022. In this example, the optical waveguide 1023 extends in a direction inclined by φ counterclockwise with respect to the Z-axis direction, which is the normal direction of the end faces 1021 and 1022. A gain region is provided in the optical waveguide 1023. In the optical amplifier 1020, for example, excited carriers are generated by injecting current into the gain region of the optical waveguide 1023. This amplifies the output light L2 guided by the optical waveguide 1023 to the desired intensity. The amplified output light L2 is emitted to the outside from the end face 1022.
[0024] In the optical element 100, an additional optical waveguide 21 is provided near the optical waveguide 11, extending between the end face 21A and the reference light intensity monitoring unit 2. The end face 21A is provided so as to belong to the same plane as the end face 110 of the optical element 100. The optical waveguide 21 is formed parallel to the optical waveguide 11, allowing input light L1 from the light-emitting element 1010 to be incident onto it, similar to the optical waveguide 11. Therefore, the optical waveguide 21 extends in a direction inclined by an angle φ clockwise with respect to the Z-axis direction, which is the normal direction of the end face 21A, similar to the optical waveguide 11. The optical waveguide 21 is provided on the substrate 101 at a distance D1 from the optical waveguide 11 in the +X-axis direction, which intersects with the extension direction of the optical waveguide 21.
[0025] Hereafter, optical waveguide 21 will also be referred to as the third optical waveguide. The direction parallel to the X-axis in which optical waveguide 21 is separated from optical waveguide 11 will also be referred to as the first direction. The plane parallel to the XY plane to which end faces 110, 11A, and 21A belong will also be referred to as the first plane. The Y-axis direction, which is the axis of inclination of the optical waveguide 21 in the direction of extension with respect to the first plane to which end face 21A of optical waveguide 21 belongs, will be referred to as the third direction. Furthermore, the clockwise angle φ indicating the inclination of optical waveguide 21 will also be referred to as the first angle.
[0026] The reference light intensity monitoring unit 2 receives the input light L1 incident on the optical waveguide 21 as reference light for aligning the light-emitting element 1010. The reference light intensity monitoring unit 2 then monitors the intensity of the input light L1, which is the reference light. Hereinafter, the input light L1 incident on the optical waveguide 21 from the light-emitting element 1010 as reference light will also be referred to as the first reference light. The reference light intensity monitoring unit 2 will also be referred to as the first reference light intensity monitoring unit.
[0027] Furthermore, in the optical element 100, an optical waveguide 22 is provided near the optical waveguide 12, extending between the end face 22A and the reference light intensity monitoring unit 3. The end face 22A is provided so as to belong to the same plane as the end face 110 of the optical element. The optical waveguide 22 is formed as an optical waveguide parallel to the optical waveguide 12. Therefore, like the optical waveguide 12, the optical waveguide 22 extends in a direction inclined by φ counterclockwise with respect to the Z-axis direction, which is the normal direction of the end face 22A. On the substrate 101, the optical waveguide 22 is provided at a position separated from the optical waveguide 12 by a distance D2 in the -X-axis direction intersecting the extension direction of the optical waveguide 22.
[0028] Hereinafter, optical waveguide 22 will also be referred to as the fourth optical waveguide. The direction parallel to the X-axis in which optical waveguide 22 is separated from optical waveguide 12 will also be referred to as the second direction. The plane parallel to the XY plane to which end faces 110, 12A, and 22A belong will also be referred to as the second plane. The Y-axis direction, which is the axis of inclination of the optical waveguide 22 in the direction of extension with respect to the second plane to which end face 22A of optical waveguide 22 belongs, will be referred to as the fourth direction. The counterclockwise angle φ indicating the inclination of optical waveguide 22 will also be referred to as the second angle.
[0029] The reference light intensity monitoring unit 3 receives the reference light L3 incident on the optical waveguide 22 as reference light for aligning the optical amplifier 1020. The reference light intensity monitoring unit 3 then monitors the intensity of the reference light L3. Hereinafter, the reference light L3 incident on the optical waveguide 22 from the optical amplifier 1020 will also be referred to as the second reference light. The reference light intensity monitoring unit 3 will also be referred to as the second reference light intensity monitoring unit.
[0030] As explained above, it can be understood that in the optical element 100, the optical waveguides 11 and 21 are arranged so that they move away from the optical waveguides 12 and 22 as they approach the end face.
[0031] Next, the alignment of the light-emitting element 1010 and the optical amplifier 1020 relative to the optical element 100 will be described. Figure 3 is a flowchart of the alignment process according to one embodiment. In this embodiment, as shown in Figure 3, steps S11 and S12 for aligning the light-emitting element 1010 and steps S21 and 22 for aligning the optical amplifier 1020 are performed in parallel.
[0032] Step S1 First, the light-emitting element 1010 is placed in its initial position. Figure 4 is a schematic diagram showing the arrangement of the optical elements, light-emitting element, and optical amplifier at the start of alignment. Here, the light-emitting element 1010 is positioned so that the end face of the optical waveguide 1013 of the light-emitting element 1010 is located near the end face 21A of the optical waveguide 21. Similarly to the light-emitting element 1010, the optical amplifier 1020 is placed in its initial position. Here, the optical amplifier 1020 is positioned so that the end face of the optical waveguide 1023 of the optical amplifier 1020 is located near the end face 22A of the optical waveguide 22.
[0033] In the following, the alignment operation is performed by driving the light-emitting element 1010 and the optical amplifier 1020 according to the results of monitoring the light intensity by the reference light intensity monitoring units 2 and 3. Figure 5 shows an example of the alignment operation of the light-emitting element and the optical amplifier. Various driving means may be used to drive the light-emitting element 1010 and the optical amplifier 1020. For example, the positions of the light-emitting element 1010 and the optical amplifier 1020 may be adjusted by moving the probe while adsorbing it onto the upper surfaces of the light-emitting element 1010 and the optical amplifier 1020 with an adsorption probe. The control unit 1300 controls the drive units 1100 and 1200 by providing drive signals DR1 and DR2 according to the monitor signals M1 and M2 indicating the results of monitoring the light intensity by the reference light intensity monitoring units 2 and 3. As a result, the control unit 1300 can move the light-emitting element 1010 and the optical amplifier 1020 to a desired position and hold that position.
[0034] Step S11 The control unit 1300 monitors the intensity of the input light L1 received by the reference light intensity monitoring unit 2 based on the monitor signal M1, while the light-emitting element 1010 is outputting input light L1. The control unit 1300 may also control the output of the input light L1 from the light-emitting element 1010 by controlling, for example, an external power supply. The control unit 1300 then drives the light-emitting element 1010 along the horizontal direction (i.e., the X-axis direction) and the vertical direction (i.e., the Y-axis direction) using the drive unit 1100. The control unit 1300 maintains the positional relationship between the light-emitting element 1010 and the optical waveguide 21 at a position where the intensity of the monitored input light L1 falls within a predetermined range, preferably at a position where the intensity of the input light L1 is at its maximum.
[0035] Step S12 By moving the light-emitting element 1010 along the X-axis by a predetermined distance after alignment is complete, the optical waveguide 1013 of the light-emitting element 1010 is aligned with the optical waveguide 11 of the optical element 100. Figure 6 shows an example of alignment performed by moving the light-emitting element and the optical amplifier. In this example, as shown in Figure 6, the light-emitting element 1010 is moved by a distance D1 in the -X-axis direction. This makes it easy to align the optical waveguide 1013 and the optical waveguide 11.
[0036] Step S21 When current is injected into the optical amplifier 1020, the active region of the optical waveguide 1023 emits light. As a result, reference light L3 is emitted from the optical waveguide 1023 toward the optical element 100. In this state, the control unit 1300 monitors the intensity of the reference light L3 received by the reference light intensity monitoring unit 3 based on the monitor signal M2. The control unit 1300 drives the optical amplifier 1020 along the horizontal direction (i.e., the X-axis direction) and the vertical direction (i.e., the Y-axis direction) using the drive unit 1200. The control unit 1300 then maintains the positional relationship between the optical amplifier 1020 and the optical waveguide 22 at a position where the intensity of the monitored reference light L3 falls within a predetermined range, preferably at a position where the intensity of the reference light L3 is maximum. The control unit 1300 may also control the output of the reference light L3 from the optical amplifier 1020 by controlling, for example, an external power supply.
[0037] Step S22 By moving the optical amplifier 1020 along the X-axis by a predetermined distance after alignment is complete, the optical waveguide 1023 of the optical amplifier 1020 is aligned with the optical waveguide 12 of the optical element 100. In this example, as shown in Figure 6, the optical amplifier 1020 is moved by a distance D2 in the +X-axis direction. This makes it easy to align the optical waveguide 1023 with the optical waveguide 12.
[0038] As explained above, with the optical element 100, the alignment of the light-emitting element 1010 and the alignment of the optical amplifier 1020 can be performed independently. Therefore, the alignment of the light-emitting element 1010 and the alignment of the optical amplifier 1020 can be performed simultaneously.
[0039] It is known that when aligning a light-emitting element and an optical amplifier sequentially with respect to an optical element using a general alignment method, it generally takes several tens of minutes, for example, about 30 minutes. In contrast, by using the optical element 100, the light-emitting element and the optical amplifier can be aligned with respect to the optical element simultaneously, thus reducing the working time to half, for example, about 15 minutes, compared to a general alignment method.
[0040] Furthermore, in a typical alignment method, when aligning the light-emitting element 1010, the intensity of the output light L2 after wavelength filtering by the wavelength control unit 1 is monitored by the output light intensity monitoring unit 4. Therefore, time was required for wavelength control in the wavelength control unit 1 to stabilize the output light L2. In contrast, by using the optical element 100, the reference light intensity monitoring unit 2 monitors the intensity of the input light L1 input from the light-emitting element 1010 via the optical waveguide 21. As a result, there is no need to control the wavelength control unit 1 when aligning the light-emitting element 1010. Therefore, by using the optical element 100, the time required for controlling the wavelength control unit 1 can be further reduced. As a result, by using the optical element 100, the working time can be reduced to about one-third, for example, about 10 minutes, compared to a typical alignment method.
[0041] Therefore, the optical element 100 significantly reduces the time required for aligning the light-emitting element and the optical amplifier. In other words, it allows for efficient alignment of opposing optical paths.
[0042] Embodiment 2 In Embodiment 1, a configuration was described in which the optical element 100 is provided with a wavelength control unit 1 and an output light intensity monitoring unit 4. However, it is possible to incorporate a modulator into the optical element. This makes it possible to configure a wavelength-tunable optical transmitter.
[0043] Figure 7 is a schematic top view showing the configuration of an optical element according to one embodiment. The optical element 200 according to this embodiment has a configuration in which a modulator 5 is added to the optical element 100 according to Embodiment 1.
[0044] Modulator 5 is inserted into optical waveguide 12. Modulator 5 modulates output light L2 in response to a modulation signal applied, for example, from a modulator driver (not shown). The modulated output light L2 is incident from optical waveguide 12 into optical waveguide 1023 of optical amplifier 1020. Optical amplifier 1020 amplifies the modulated output light L2.
[0045] The other configurations and alignment procedures for the optical element 200 are the same as in Embodiment 1, so redundant explanations will be omitted.
[0046] In the optical element 200, the optical waveguides 21 and 22 used for alignment and the reference light intensity monitoring units 2 and 3 are provided independently of the wavelength control and modulation functions of the optical element. This allows for easy alignment without being affected by the configuration related to the wavelength control and modulation functions of the optical element.
[0047] Embodiment 3 The optical element according to Embodiment 3 will now be described. Figure 8 is a schematic top view showing the configuration of the optical element according to one embodiment. The optical element 300 according to this embodiment has a configuration in which electrodes 31-35, 41 and 42 are added to the optical element 100 according to Embodiment 1. Hereinafter, electrodes 31-35 will also be referred to as the first electrode group. Electrodes 41-42 will also be referred to as the second electrode group.
[0048] Electrodes 31-35 are arranged in the Z-axis direction at the +X-axis end of the substrate 101, where the reference light intensity monitoring unit 2 is located. Electrodes 31-35 are used to control the operation of the optical element 300. Electrode 31 is connected to the output light intensity monitoring unit 4. Electrode 32 is connected to the wavelength control unit 1. Electrodes 33-35 are connected to components (not shown) provided on the optical element 300, such as modulators and control units. This allows external devices to monitor the intensity of the output light L2 by observing the monitor signal from electrode 31, which indicates the intensity of the output light L2 from the output light intensity monitoring unit 4. Furthermore, by inputting a wavelength control signal to electrode 32, the passband of the wavelength control unit 1 can be controlled, for example.
[0049] Electrodes 41 and 42 are positioned on the substrate 101 opposite to electrodes 31-35. That is, electrodes 41 and 42 are arranged side by side in the Z-axis direction at the -X-axis end, which is the side where the reference light intensity monitoring unit 3 is located. Electrodes 41 and 42 are used for alignment work of the light-emitting element 1010 and the optical amplifier 1020. Electrodes 41 and 42 are connected to the reference light intensity monitoring units 2 and 3, respectively. As a result, as shown in Figures 5 and 6, the control unit 1300 can monitor the monitor signal M1 output from electrode 31 and the monitor signal M2 output from electrode 32.
[0050] In the optical element 300, electrodes 31-35 used during operation of the optical element and electrodes 41 and 42 used only for alignment are physically separated. This makes it easy to distinguish between electrodes 31-35 used during operation of the optical element and electrodes 41 and 42 used only for alignment.
[0051] This allows the operator performing the alignment work to easily identify the electrodes 41 and 42 to be used. As a result, the alignment work can be shortened.
[0052] Furthermore, when mounting the optical element in a communication device or the like, the risk of mistaking electrodes 41 and 42, which are used only for alignment, for electrodes 31-35, which are used during the operation of the optical element, can be reduced. This helps to suppress the occurrence of wiring errors.
[0053] Other embodiments Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure can be made as can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.
[0054] In the above-described embodiment, an example was given in which the end faces 11A of the optical waveguide 11, 12A of the optical waveguide 12, 21A of the optical waveguide 21, and 22A of the optical waveguide 22 are located on the same plane as the end face 110. However, this is merely an example. To align the light-emitting element 1010, it is sufficient that the end face 11A of the optical waveguide 11 and the end face 21A of the optical waveguide 21 are located on the same plane. Similarly, to align the optical amplifier 1020, it is sufficient that the end face 12A of the optical waveguide 12 and the end face 22A of the optical waveguide 22 are located on the same plane. Therefore, the first plane to which the end faces 11A and 21A belong and the second plane to which the end faces 11A and 22A belong may be different planes.
[0055] In the optical element according to Embodiment 2, electrodes 31-35, 41, and 42 may also be provided, similar to the optical element according to Embodiment 3. Furthermore, in the embodiments described above, electrodes 31-35, 41, and 42 are merely illustrative examples, and any number of electrodes may be provided.
[0056] In the above-described embodiment, an example was given in which the optical waveguides 11 and 21 are arranged so that they move away from the optical waveguides 12 and 22 as they approach the end face, but this is merely illustrative. The optical waveguides 11 and 21 may also be arranged so that they move closer to the optical waveguides 12 and 22 as they approach the end face. Alternatively, the optical waveguides 11 and 21 may be arranged parallel to the optical waveguides 12 and 22.
[0057] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps shown in any of the drawings may be changed as appropriate.
[0058] Some or all of the above embodiments may also be described as follows, but are not limited to the following:
[0059] (Note 1) A first optical waveguide into which the input light is incident, Wavelength control means for wavelength filtering the input light guided by the first optical waveguide to output output light of a desired wavelength, A second optical waveguide that guides the output light, Output light intensity monitoring means for monitoring the intensity of the output light guided by the second optical waveguide, A third optical waveguide is provided parallel to the first optical waveguide and spaced apart from the first optical waveguide along a first direction that intersects the direction in which the first optical waveguide extends, A first reference light intensity monitoring means for monitoring the intensity of the first reference light input to the third optical waveguide, A fourth optical waveguide is provided parallel to the second optical waveguide and spaced apart from the second optical waveguide along a second direction intersecting the direction in which the second optical waveguide extends, The system includes a second reference light intensity monitoring means for monitoring the intensity of the second reference light input to the fourth optical waveguide, The end face into which the input light is incident in the first optical waveguide and the end face into which the first reference light is input in the third optical waveguide belong to a first plane parallel to the first direction and a third direction perpendicular to the first direction and the direction in which the first and third optical waveguides extend. The end face from which the output light is emitted in the second optical waveguide and the end face from which the second reference light is input in the fourth optical waveguide belong to a second plane parallel to the second direction and to a fourth direction perpendicular to the second direction and the direction in which the second and fourth optical waveguides extend. Optical element.
[0060] (Note 2) The first and third optical waveguides extend in a direction inclined by a first angle with respect to the first plane, with respect to the third direction as the axis. The second and fourth optical waveguides extend in a direction inclined by a second angle with respect to the second plane, with respect to the fourth direction as the axis. The optical element described in Appendix 1.
[0061] (Note 3) The first and second directions are the same predetermined direction. The third and fourth directions are the same direction. The first and second surfaces are the same predetermined surface. The optical element described in Appendix 2.
[0062] (Note 4) The first angle and the second angle are opposite angles centered on the axis. The optical element described in Appendix 3.
[0063] (Note 5) The absolute value of the first angle and the absolute value of the second angle are the same. The optical element described in Appendix 4.
[0064] (Note 6) The first and third optical waveguides are arranged so as they move toward the predetermined plane, they move away from the second and fourth optical waveguides. The optical element described in Appendix 4 or 5.
[0065] (Note 7) A first electrode group comprising a plurality of electrodes, including at least one electrode connected to the output light intensity monitoring means and the wavelength control means, The system comprises a second group of electrodes connected to the first and second reference light intensity monitoring means, The first electrode group and the second electrode group are provided separated in the predetermined direction. The optical element according to any one of claims 3 to 6.
[0066] (Note 8) The second optical waveguide is provided with optical modulation means for modulating the output light. The optical element according to any one of claims 1 to 7.
[0067] (Note 9) The aforementioned optical element is configured as a silicon photonic optical element formed on a silicon substrate. The optical element according to any one of claims 1 to 8.
[0068] (Note 10) A first optical waveguide that guides the input light, Wavelength control means for wavelength filtering the input light guided by the first optical waveguide to output output light of a desired wavelength, A second optical waveguide that guides the output light, Output light intensity monitoring means for monitoring the intensity of the output light guided by the second optical waveguide, A third optical waveguide is provided parallel to the first optical waveguide and is spaced a distance apart from the first optical waveguide along a first direction that intersects the direction in which the first optical waveguide extends, A first reference light intensity monitoring means for monitoring the intensity of the first reference light input to the third optical waveguide, A fourth optical waveguide is provided parallel to the second optical waveguide, separated from the second optical waveguide by a second distance along a second direction that intersects the direction in which the second optical waveguide extends, The system includes a second reference light intensity monitoring means for monitoring the intensity of the second reference light input to the fourth optical waveguide, The end face into which the input light is incident in the first optical waveguide and the end face into which light is input in the third optical waveguide belong to a first plane parallel to the first direction and to a third direction perpendicular to the first direction and the direction in which the first and third optical waveguides extend. The end face from which the output light is emitted in the second optical waveguide and the end face from which the second reference light is input in the fourth optical waveguide are, with respect to an optical element belonging to a second plane parallel to the second direction and to a fourth direction perpendicular to the second direction and the direction in which the second and fourth optical waveguides extend, The first alignment, which aligns the first element capable of outputting light, and the second alignment, which aligns the second element capable of outputting light, are performed in parallel. In the first adjustment described above, With the first reference light output from the first element to the third optical waveguide, the position of the first element relative to the third optical waveguide is adjusted while monitoring the intensity of the first reference light using the first reference light intensity monitoring means. The first element is held at a position where the intensity of the first reference light falls within a predetermined first range. From the position in which the first element is held, the first element is moved by a first distance in a direction toward the first optical waveguide along the first direction, In the second adjustment described above, With the second reference light output from the second element to the fourth optical waveguide, the position of the second element relative to the fourth optical waveguide is adjusted while monitoring the intensity of the second reference light using the second reference light intensity monitoring means. The second element is held at a position where the intensity of the second reference light falls within a predetermined second range. From the position where the second element is held, the second element is moved by the second distance in the direction toward the second optical waveguide along the second direction. Alignment method. [Explanation of symbols]
[0069] 1 Wavelength control unit 2, 3 Reference light intensity monitoring section 4. Output light intensity monitoring unit 5 Modulator 11~13, 21, 22, 1013, 1023 Optical waveguide 11A, 12A, 21A, 22A, 110, 1011, 1012, 1021, 1022 End face 31~35, 41, 42 electrode 100, 200, 300 optical elements 101 circuit board 1000 wavelength tunable light source 1010 Light-emitting element 1020 Optical Amplifier 1100, 1200 Drive Unit 1300 Control Unit L1 Input Light L2 Output Light L3 Reference Light M1, M2 monitor signals
Claims
1. A first optical waveguide into which the input light is incident, Wavelength control means for wavelength filtering the input light guided by the first optical waveguide to output output light of a desired wavelength, A second optical waveguide that guides the output light, Output light intensity monitoring means for monitoring the intensity of the output light guided by the second optical waveguide, A third optical waveguide is provided parallel to the first optical waveguide and spaced apart from the first optical waveguide along a first direction that intersects the direction in which the first optical waveguide extends, A first reference light intensity monitoring means for monitoring the intensity of the first reference light input to the third optical waveguide, A fourth optical waveguide is provided parallel to the second optical waveguide and spaced apart from the second optical waveguide along a second direction intersecting the direction in which the second optical waveguide extends, The system includes a second reference light intensity monitoring means for monitoring the intensity of the second reference light input to the fourth optical waveguide, The end face into which the input light is incident in the first optical waveguide and the end face into which the first reference light is input in the third optical waveguide belong to a first plane parallel to the first direction and a third direction perpendicular to the first direction and the direction in which the first and third optical waveguides extend. The end face from which the output light is emitted in the second optical waveguide and the end face from which the second reference light is input in the fourth optical waveguide belong to a second plane parallel to the second direction and to a fourth direction perpendicular to the second direction and the direction in which the second and fourth optical waveguides extend. Optical element.
2. The first and third optical waveguides extend in a direction inclined by a first angle with respect to the first plane, with respect to the third direction as the axis. The second and fourth optical waveguides extend in a direction inclined by a second angle with respect to the second plane, with respect to the fourth direction as the axis. The optical element according to claim 1.
3. The first and second directions are the same predetermined direction, The third and fourth directions are the same direction. The first and second surfaces are the same predetermined surface. The optical element according to claim 2.
4. The first angle and the second angle are opposite angles centered on the axis. The optical element according to claim 3.
5. The absolute value of the first angle and the absolute value of the second angle are the same. The optical element according to claim 4.
6. The first and third optical waveguides are arranged so as they move toward the predetermined plane, they move away from the second and fourth optical waveguides. The optical element according to claim 4.
7. A first electrode group comprising a plurality of electrodes, including at least one electrode connected to the output light intensity monitoring means and the wavelength control means, The system comprises a second electrode group consisting of electrodes connected to the first and second reference light intensity monitoring means, The first electrode group and the second electrode group are provided separated in the predetermined direction. The optical element according to claim 3.
8. The second optical waveguide is provided with optical modulation means for modulating the output light. The optical element according to claim 1 or 2.
9. The aforementioned optical element is configured as a silicon photonic optical element formed on a silicon substrate. The optical element according to claim 1 or 2.
10. A first optical waveguide that guides the input light, A wavelength control means that wavelength filters the input light guided by the first optical waveguide to output output light of a desired wavelength, A second optical waveguide that guides the output light, Output light intensity monitoring means for monitoring the intensity of the output light guided by the second optical waveguide, A third optical waveguide is provided parallel to the first optical waveguide and is spaced a distance apart from the first optical waveguide along a first direction that intersects the direction in which the first optical waveguide extends, A first reference light intensity monitoring means for monitoring the intensity of the first reference light input to the third optical waveguide, A fourth optical waveguide is provided parallel to the second optical waveguide, separated from the second optical waveguide by a second distance along a second direction that intersects the direction in which the second optical waveguide extends, The system includes a second reference light intensity monitoring means for monitoring the intensity of the second reference light input to the fourth optical waveguide, The end face into which the input light is incident in the first optical waveguide and the end face into which light is input in the third optical waveguide belong to a first plane parallel to the first direction and a third direction perpendicular to the first direction and the direction in which the first and third optical waveguides extend. The end face from which the output light is emitted in the second optical waveguide and the end face from which the second reference light is input in the fourth optical waveguide are, with respect to an optical element belonging to a second plane parallel to the second direction and to a fourth direction perpendicular to the second direction and the direction in which the second and fourth optical waveguides extend, The first alignment, which aligns the first element capable of outputting light, and the second alignment, which aligns the second element capable of outputting light, are performed in parallel. In the first adjustment described above, With the first reference light output from the first element to the third optical waveguide, the position of the first element relative to the third optical waveguide is adjusted while monitoring the intensity of the first reference light using the first reference light intensity monitoring means. The first element is held at a position where the intensity of the first reference light falls within a predetermined first range. From the position in which the first element is held, the first element is moved by a first distance in a direction toward the first optical waveguide along the first direction. In the second adjustment described above, With the second reference light output from the second element to the fourth optical waveguide, the position of the second element relative to the fourth optical waveguide is adjusted while monitoring the intensity of the second reference light using the second reference light intensity monitoring means. The second element is held at a position where the intensity of the second reference light falls within a predetermined second range. From the position in which the second element is held, the second element is moved by the second distance in the direction toward the second optical waveguide along the second direction. Alignment method.