Wavelength variable laser device and method for configuring the same

Abstract

To achieve a reduced size in a wavelength variable laser device with a simple configuration.SOLUTION: A wavelength variable optical resonator includes a wavelength variable filter, and first and second waveguides each including a part inclined relative to a first end surface in such a way that the first and second waveguides are separated from each other from the wavelength variable filter toward the first end surface. A first optical amplifier includes a third waveguide including an active region, the third waveguide being provided between a second end surface which faces the first end surface and a third end surface which is opposed to the second end surface and on which reflection means is provided, the third waveguide further including a part that is inclined relative to the second end surface and is extended from the second end surface in such a way that the third waveguide and the first waveguide are coaxial with each other. A second optical amplifier amplifies laser light propagating through a fourth waveguide after the laser light whose wavelength is adjusted to a desired wavelength by the wavelength variable filter is input to the fourth waveguide via a fourth end surface facing the first end surface, the fourth waveguide including a part that is inclined relative to the fourth end surface and is extended from the fourth end surface in such a way that the fourth waveguide and the second waveguide are coaxial with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wavelength tunable laser device and a method for configuring the same. [Background technology]

[0002] In optical communications, wavelength-tunable lasers capable of adjusting the wavelength of output laser light are used when communications are performed using wavelength-multiplexed optical signals.

[0003] A wavelength-tunable laser is constructed by connecting a wavelength-tunable filter chip, which is an external resonator, to a semiconductor optical amplifier. In this case, the effective refractive indexes of the waveguides in the wavelength-tunable filter chip and the waveguides in the semiconductor optical amplifier are different, so connecting waveguides perpendicular to the end facets causes reflection. As a result, laser oscillation becomes unstable. Therefore, to suppress the effects of reflection, it is desirable to connect waveguides tilted at a predetermined angle to the end facets so as to minimize the effects of reflection, as in Patent Document 1.

[0004] Furthermore, in a wavelength tunable laser, it is required to independently stabilize laser oscillation and control optical output. Therefore, as in Non-Patent Document 1, two semiconductor optical amplifiers, a semiconductor optical amplifier (SOA: Semiconductor Optical Amplifier) ​​for laser oscillation and a semiconductor optical amplifier (BOA: Booster Optical Amplifier) ​​for optical output, are connected to a wavelength tunable filter chip. In this configuration, the SOA, the BOA, and the wavelength tunable filter chip are cascaded in the waveguiding direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-108714 [Non-patent literature]

[0006] [Non-Patent Document 1] Naoki Kobayashi, et al., “Silicon Photonic Hybrid Ring-Filter External Cavity Wavelength Tunable Lasers”, Journal of Lightwave Technology, vol. 33, No. 6, March 15, 2015, pp. 1241-1246 Summary of the Invention [Problem to be solved by the invention]

[0007] In Non-Patent Document 1, the SOA, BOA, and tunable filter chip are cascaded in the waveguide direction, which increases the dimension of the tunable laser in the waveguide direction, making it difficult to miniaturize the tunable laser.

[0008] To solve this problem, it is possible to arrange the SOA and BOA side by side on one end face of the tunable filter chip. However, simply arranging the SOA and BOA side by side on the same end face increases the size of the tunable filter chip in the direction parallel to the end face, which is the direction in which the SOA and BOA are arranged. This limits the miniaturization of the tunable laser device in the direction in which the SOA and BOA are arranged. [Means for solving the problem]

[0009] A wavelength-tunable laser device according to one aspect of the present disclosure comprises: a wavelength-tunable optical resonator having a wavelength-tunable filter capable of adjusting the wavelength of output light, the wavelength-tunable optical resonator having first and second waveguides including portions inclined with respect to the first end face so as to be spaced apart from each other from the wavelength-tunable filter toward the first end face; a first optical amplifier having a third waveguide including an active region disposed between a second end face facing the first end face and a third end face opposite the second end face on which reflecting means is provided, the third waveguide including a portion inclined with respect to the second end face so as to be coaxial with the first waveguide and extending from the second end face; and a second optical amplifier configured to amplify the laser light propagating through the fourth waveguide, the laser light being oscillated by the resonator configured between the wavelength-tunable filter and the reflecting means and being tuned to a desired wavelength by the wavelength-tunable filter, and inputting the laser light into a fourth waveguide including a portion inclined with respect to the fourth end face so as to be coaxial with the second waveguide and extending from the fourth end face, via a fourth end face facing the first end face.

[0010] A method for configuring a wavelength-tunable laser device according to one aspect of the present disclosure includes providing a wavelength-tunable optical resonator having a wavelength-tunable filter capable of adjusting the wavelength of output light, the wavelength-tunable optical resonator having first and second waveguides including portions inclined with respect to the first end face so as to be spaced apart from each other from the wavelength-tunable filter toward a first end face; providing a first optical amplifier having a third waveguide including an active region provided between a second end face facing the first end face and a third end face opposite the second end face on which reflecting means is provided, the third waveguide including a portion inclined with respect to the second end face so as to be coaxial with the first waveguide; and providing a second optical amplifier in which laser light oscillated by the resonator configured between the wavelength-tunable filter and the reflecting means is input to a fourth waveguide including a portion inclined with respect to the fourth end face so as to be coaxial with the second waveguide and to be coaxial with the second waveguide, via a fourth end face facing the first end face. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to achieve miniaturization of a wavelength tunable laser device with a simple configuration. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a configuration of a wavelength tunable laser device according to an embodiment; [Figure 2] FIG. 1 is a diagram schematically illustrating the configuration of a general wavelength tunable laser device. [Figure 3] FIG. 1 is a diagram illustrating a first example of miniaturization of a wavelength tunable laser device. [Figure 4] FIG. 10 is a diagram illustrating a second example of miniaturization of a wavelength tunable laser device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same elements are designated by the same reference numerals, and redundant explanations will be omitted as necessary.

[0014] Embodiment 1 A wavelength tunable laser device according to a first embodiment will be described. FIG. 1 is a diagram schematically illustrating the configuration of a wavelength tunable laser device according to one embodiment. The wavelength tunable laser device 100 has a wavelength tunable optical resonator 1 and two semiconductor optical amplifiers. In this configuration, the two semiconductor optical amplifiers are a semiconductor optical amplifier (SOA: Semiconductor Optical Amplifier) ​​2 for laser oscillation and a semiconductor amplifier (BOA: Booster Optical Amplifier) ​​3 for optical output. The wavelength tunable optical resonator 1, SOA 2, and BOA 3 are mounted on, for example, a substrate (not shown).

[0015] Hereinafter, the horizontal direction from left to right on the paper surface of the drawing, which is the longitudinal direction of the wavelength tunable laser device, will be referred to as the X direction. The vertical direction from bottom to top on the paper surface of the drawing, which is the lateral direction of the wavelength tunable laser device, will be referred to as the Y direction. Herein, the +Y direction will also be referred to as the first direction, and the -Y direction will also be referred to as the second direction.

[0016] The end face on the +X direction side where light enters and exits the wavelength tunable optical resonator 1 is referred to as end face 1A. On the side of end face 1A of the wavelength tunable optical resonator 1, SOA 2 and BOA 3 are arranged in the Y direction, which is a direction parallel to end face 1A. In the following, each end face of the wavelength tunable optical resonator 1, SOA 2, and BOA 3 is a surface perpendicular to the longitudinal direction, i.e., the X direction.

[0017] In this configuration, it is desirable to arrange SOA2 and BOA3 with a predetermined distance between them. This is effective in avoiding any adverse effects during mounting. For example, if SOA2 is mounted first and then BOA3 is mounted, if the mounting positions of SOA2 and BOA3 are close to each other, there is a risk that BOA3 may come into contact with SOA2, or that the jig used to mount BOA3 may come into contact with SOA2. This may cause axial misalignment of one or both of SOA2 and BOA3, resulting in unstable laser oscillation. To avoid such problems that may arise during the mounting process, it is desirable to arrange SOA2 and BOA3 far enough apart that no physical interference occurs during mounting.

[0018] Furthermore, by separating the SOA 2 and the BOA 3, it is possible to prevent or suppress the influence of heat generated by one on the other.

[0019] The tunable optical resonator 1 has a tunable filter 10, straight waveguides 11 and 12, and inclined waveguides 13 and 14. The straight waveguide 11 and the inclined waveguide 13 form a path connecting the tunable filter 10 and the SOA 2. The straight waveguide 12 and the inclined waveguide 14 form a path connecting the tunable filter 10 and the BOA 3.

[0020] Here, straight waveguide 11 and inclined waveguide 13 are also referred to as first waveguides. Straight waveguide 11 is also referred to as the seventh portion included in the first waveguide. Inclined waveguide 13 is also referred to as the sixth portion included in the first waveguide. Straight waveguide 12 and inclined waveguide 14 are also referred to as second waveguides. Straight waveguide 12 is also referred to as the ninth portion included in the second waveguide. Inclined waveguide 14 is also referred to as the eighth portion included in the second waveguide. End face 1A is also referred to as the first end face.

[0021] The tunable filter 10 has, for example, one or more ring waveguides and can adjust the wavelength of light propagating through the waveguides. The figure shows an example in which the tunable filter 10 has two ring waveguides. However, this tunable filter 10 is merely an example, and other configurations may be used as appropriate. Like a typical tunable filter configured with a ring waveguide, the tunable filter 10 can adjust the wavelength of light traveling to and from a resonator configured between the tunable filter 10 and a reflecting member provided on the end face of the SOA 2 to a desired wavelength. The tunable filter 10 then outputs laser light L of a desired wavelength to the BOA 3 via the straight waveguide 12 and the tilted waveguide 14.

[0022] The straight waveguide 11 and the tilted waveguide 13 are optically smoothly cascaded in the longitudinal direction of the tunable optical resonator 1. The straight waveguide 11 extends from the tunable filter 10 in the longitudinal direction of the tunable optical resonator 1 and is connected to the tilted waveguide 13. The tilted waveguide 13 extends from the connection with the straight waveguide 11 toward the end face 1A facing the SOA 2 at a predetermined angle with respect to the end face 1A. This makes it possible to suppress reflection at the end face 1A of light exiting the tilted waveguide 13 via the end face 1A and light entering the tilted waveguide 13 via the end face 1A. It is desirable to determine the angle that the tilted waveguide 13 makes with respect to the end face 1A so that the reflection of light at the end face 1A is minimized or falls within a desired range.

[0023] The straight waveguide 12 and the tilted waveguide 14 are optically smoothly cascaded in the longitudinal direction of the tunable optical resonator 1. The straight waveguide 12 extends from the tunable filter 10 in the longitudinal direction of the tunable optical resonator 1 and is connected to the tilted waveguide 14. The tilted waveguide 14 extends from the connection with the straight waveguide 12 toward the end face 1A at a predetermined angle relative to the end face 1A. However, the tilted waveguide 14 is provided so as to be tilted in the opposite direction to the tilted waveguide 13. In other words, the tilted waveguides 13 and 14 are provided so as to be spaced apart from each other as they approach the end face 1A. This makes it possible to suppress reflection at the end face 1A of light emitted from the tilted waveguide 14 via the end face 1A. It is desirable to determine the angle that the tilted waveguide 14 forms with respect to the end face 1A so that light reflection at the end face 1A is minimized or within a desired range.

[0024] It is desirable that the inclined waveguide 13 and the inclined waveguide 14 are inclined in opposite directions with respect to an axis along the X direction. The inclined waveguide 13 and the inclined waveguide 14 may also be arranged symmetrically with respect to the axis along the X direction. That is, the angle of inclination of the inclined waveguide 13 in the clockwise direction with respect to the end face 1A and the angle of inclined waveguide 14 in the counterclockwise direction with respect to the end face 1A may be the same angle.

[0025] The SOA 2 is configured as a light-emitting device having an active region, for example, a semiconductor optical amplifier.

[0026] The SOA 2 has a straight waveguide 21 and a tilted waveguide 22 that are optically smoothly cascaded in the longitudinal direction of the SOA 2. An active region is provided in one or both of the straight waveguide 21 and the tilted waveguide 22, or is provided adjacent to them. The tilted waveguide 22 and the straight waveguide 21 are provided in this order between an end face 2A facing the end face 1A and an end face 2B opposite the end face 2A. A member that reflects light incident from the end face 2B, such as a total reflection mirror 23, is formed on the end face 2B. The total reflection mirror 23 may be, for example, a mirror formed of a multilayer film.

[0027] Here, SOA 2 is also referred to as a first optical amplifier. Straight waveguide 21 and tilted waveguide 22 are also referred to as a third waveguide. Tilt waveguide 22 is also referred to as a first portion included in the third waveguide. Straight waveguide 21 is also referred to as a second portion included in the third waveguide. End faces 2A and 2B are also referred to as second and third end faces, respectively.

[0028] The inclined waveguide 22 extends from the connection portion with the straight waveguide 21 extending in the longitudinal direction of the SOA 2 toward the end face 2A at a predetermined angle with respect to the end face 2A. The inclined waveguide 22 is inclined so as to extend in the same direction as the inclined waveguide 13 of the wavelength tunable optical resonator 1. The SOA 2 is arranged so that the inclined waveguide 22 and the inclined waveguide 13 are coaxial. This makes it possible to suppress reflection at the end face 2A of light emitted from the inclined waveguide 22 via the end face 2A and light incident on the inclined waveguide 22 via the end face 2A. It is desirable to determine the angle that the inclined waveguide 22 makes with respect to the end face 2A so that the reflection of light at the end face 2A is minimized or falls within a desired range.

[0029] The BOA 3 is configured as an optical amplifier that amplifies laser light incident on the optical waveguide provided therein, and is configured as, for example, a semiconductor optical amplifier.

[0030] The BOA 3 has a straight waveguide 31 and inclined waveguides 32 and 33 that are cascaded in the longitudinal direction of the BOA 3. The inclined waveguide 32, the straight waveguide 31, and the inclined waveguide 33 are connected in this order from an end face 3A facing the end face 1A toward an end face 3B that is the light emission face.

[0031] Here, BOA 3 is also referred to as a second optical amplifier. Straight waveguide 31 and tilted waveguides 32 and 33 are also referred to as a fourth waveguide. Tilt waveguide 32 is also referred to as a third portion included in the fourth waveguide. Straight waveguide 31 is also referred to as a fourth portion included in the fourth waveguide. Tilt waveguide 33 is also referred to as a fifth portion included in the fourth waveguide. End faces 3A and 3B are also referred to as fourth and fifth end faces, respectively.

[0032] The inclined waveguide 32 extends from the connection portion with the straight waveguide 31 extending in the longitudinal direction of the BOA 3 toward the end face 3A at a predetermined angle with respect to the end face 3A. The inclined waveguide 32 is inclined so as to extend in the same direction as the inclined waveguide 14 of the wavelength tunable optical resonator 1. The BOA 3 is arranged so that the inclined waveguide 32 and the inclined waveguide 14 are coaxial. This makes it possible to suppress reflection at the end face 3A of light incident on the inclined waveguide 32 via the end face 3A. It is desirable to determine the angle that the inclined waveguide 32 makes with respect to the end face 3A so that the reflection of light at the end face 3A is minimized or falls within a desired range.

[0033] The inclined waveguide 33 extends from the connection portion with the straight waveguide 31 toward the end face 3B at a predetermined angle with respect to the end face 3B. This makes it possible to suppress reflection at the end face 3B of light emitted from the inclined waveguide 33 via the end face 3B. It is desirable to determine the angle that the inclined waveguide 33 makes with respect to the end face 3B so that the reflection of light at the end face 3B is minimized or falls within a desired range. The inclined waveguide 33 may be inclined so as to extend in the same direction as the inclined waveguide 32.

[0034] Next, the propagation path of light will be explained. In this configuration, the SOA 2 oscillates as laser light by injecting a current into an active region provided in, for example, a straight waveguide 21, and the light generated travels back and forth between the total reflection mirror 23 provided on the end face 2B of the SOA 2 and the tunable filter 10. In the figure, the oscillated laser light is indicated by the symbol L, and its propagation direction is indicated by an arrow. As described above, the oscillating wavelength of the laser light L can be adjusted to a desired wavelength by the tunable filter 10.

[0035] Laser light L of a desired wavelength is emitted from the wavelength tunable filter 10 to the BOA 3 through the straight waveguide 12 and the inclined waveguide 14. The laser light L incident on the BOA 3 is amplified to a desired intensity while propagating through the straight waveguide 31, the inclined waveguide 32, and the inclined waveguide 33, and then emitted from the end face 3B, which is the emission surface.

[0036] According to the above-described configuration, even if the SOA 2 and the BOA 3 are arranged at a predetermined distance in the Y direction to avoid problems that may occur when mounting the SOA 2 and the BOA 3, the size in the Y direction of the wavelength-tunable laser device 100 can be reduced. As a result, according to this configuration, it is possible to achieve a miniaturized wavelength-tunable laser device.

[0037] Next, the advantages of the wavelength tunable laser device 100 in terms of miniaturization of wavelength tunable laser devices will be explained in comparison with a general wavelength tunable laser device 900. Fig. 2 is a diagram schematically showing the configuration of a general wavelength tunable laser device. The general wavelength tunable laser device 900 has a configuration in which the wavelength tunable optical resonator 1 and the BOA 3 of the wavelength tunable laser device 100 according to the first embodiment are replaced with a wavelength tunable optical resonator 4 and a BOA 5, respectively.

[0038] The tunable filter 40, the straight waveguides 41 and 42, and the inclined waveguides 43 and 44 of the tunable optical resonator 4 correspond to the tunable filter 10, the straight waveguides 11 and 12, and the inclined waveguides 13 and 14 of the tunable optical resonator 1, respectively. However, the inclined waveguide 44 is inclined in the opposite direction to the inclined waveguide 14.

[0039] The straight waveguide 51 and the inclined waveguides 52 and 53 of the BOA 5 correspond to the straight waveguide 31 and the inclined waveguides 32 and 33 of the BOA 3, respectively. However, the straight waveguide 51 and the inclined waveguides 52 and 53 are arranged inverted along the Y direction with respect to the straight waveguide 31 and the inclined waveguides 32 and 33, respectively, i.e., symmetrical with respect to an axis along the X direction.

[0040] As described above, in the wavelength-tunable laser device 100, the tilted waveguide 22 of SOA2 and the tilted waveguide 32 of BOA3 are tilted in opposite directions, whereas in the general wavelength-tunable laser device 900, the tilted waveguide 22 of SOA2 and the tilted waveguide 52 of BOA5 are tilted in the same direction. Therefore, in the general wavelength-tunable laser device 900, if an attempt is made to maintain the distance D between SOA2 and BOA5 equal to the distance D between SOA2 and BOA3, the positions of the straight waveguide 42 and the tilted waveguide 44 of the wavelength-tunable optical resonator 4 will be shifted in the +Y direction relative to the positions of the straight waveguide 12 and the tilted waveguide 14 of the wavelength-tunable optical resonator 1. As a result, as shown by reference numeral 45 in FIG. 2 , the end of the wavelength-tunable optical resonator 4 in the +Y direction will protrude in the +Y direction beyond the SOA5.

[0041] Therefore, the dimension in the Y direction of the tunable optical resonator 4 is larger than the dimension in the Y direction of the tunable optical resonator 1. As a result, the general tunable laser device 900 is disadvantageous in terms of miniaturization of the tunable laser device compared to the tunable laser device 100.

[0042] In contrast, even when the SOA 2 and the BOA 3 are arranged at a predetermined interval in the Y direction, the wavelength tunable laser device 100 according to this embodiment can reduce the size in the Y direction compared to the general wavelength tunable laser device 900. In other words, the wavelength tunable laser device 100 makes it possible to further miniaturize the wavelength tunable laser device.

[0043] A specific example of the miniaturization effect of the wavelength tunable laser device 100 will be shown below. Fig. 3 is a diagram showing a first example of miniaturization of a wavelength tunable laser device. In this example, the dimension S of the tilted waveguides 13 and 14 of the wavelength tunable laser device 100 and the dimension S of the tilted waveguides 43 and 44 of a general wavelength tunable laser device 900 are 500 µm. The distance D between SOA2 and BOA3 and between SOA2 and BOA5 is 1200 µm.

[0044] In this example, the position of the end of the wavelength tunable optical resonator 4 in the +Y direction protrudes in the +Y direction by a shift amount P of about 450 μm from the position of the end of the wavelength tunable optical resonator 1 in the +Y direction. Therefore, it can be seen that the wavelength tunable laser device 100 can reduce the dimension in the Y direction by about 450 μm compared to the general wavelength tunable laser device 900.

[0045] 4 is a diagram showing a second example of miniaturization of a wavelength tunable laser device. In this example, the dimension S of the tilted waveguides 13 and 14 of the wavelength tunable laser device 100 and the dimension S of the tilted waveguides 43 and 44 of the general wavelength tunable laser device 900 are 750 μm. The distance D between the SOA2 and the BOA3 and between the SOA2 and the BOA5 are 1200 μm.

[0046] In this example, the position of the end of the wavelength tunable optical resonator 4 in the +Y direction protrudes in the +Y direction by a shift amount P of about 700 μm from the position of the end of the wavelength tunable optical resonator 1 in the +Y direction. Therefore, it can be seen that the wavelength tunable laser device 100 can reduce the dimension in the Y direction by about 700 μm compared to the general wavelength tunable laser device 900.

[0047] As described above, according to this configuration, the wavelength tunable laser device can be made smaller than a general wavelength tunable laser device.

[0048] Other embodiments Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0049] For example, the waveguides formed in the tunable optical resonator 1, the SOA 2, and the BOA 3 may have portions with the same width or different widths, as necessary. For example, the waveguides near the end faces may be provided with spot size converters or the like that narrow the width toward the end faces, as appropriate.

[0050] The tunable optical resonator 1, the SOA 2, and the BOA 3 may be configured as various semiconductor devices made of any material, such as silicon-based or indium phosphide-based, and may be fabricated by various semiconductor processes.

[0051] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, 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 to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0052] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0053] (Supplementary Note 1) A wavelength-tunable laser device comprising: a wavelength-tunable optical resonator having a wavelength-tunable filter capable of adjusting the wavelength of output light, the wavelength-tunable optical resonator having first and second waveguides including portions inclined with respect to the first end face so as to be spaced apart from each other from the wavelength-tunable filter toward the first end face; a first optical amplifier having a third waveguide including an active region provided between a second end face facing the first end face and a third end face opposite the second end face on which reflecting means is provided, the third waveguide including a portion inclined with respect to the second end face so as to be coaxial with the first waveguide; and a second optical amplifier configured to amplify the laser light propagating through the fourth waveguide, the second optical amplifier inputting laser light oscillated by a resonator configured between the wavelength-tunable filter and the reflecting means into a fourth waveguide including a portion inclined with respect to the fourth end face so as to be coaxial with the second waveguide and extending from the fourth end face, the fourth end face facing the first end face.

[0054] (Supplementary Note 2) The wavelength tunable laser device described in Supplementary Note 1, wherein the first waveguide is inclined relative to the first end face in a first direction parallel to the end face, and the second waveguide is inclined in a second direction opposite to the first direction.

[0055] (Supplementary Note 3) The wavelength tunable laser device according to Supplementary Note 2, wherein the first waveguide and the second waveguide are arranged symmetrically with respect to an axis perpendicular to the first end face.

[0056] (Supplementary Note 4) A wavelength-tunable laser device according to any one of Supplementary Notes 1 to 3, wherein the portion of the third waveguide inclined with respect to the second end face and the portion of the fourth waveguide inclined with respect to the fourth end face are arranged symmetrically with respect to an axis perpendicular to the first end face.

[0057] (Supplementary Note 5) The wavelength-tunable laser device according to any one of Supplementary Notes 1 to 4, wherein the third waveguide includes a first portion inclined with respect to the second end face, and a second portion extending in a direction perpendicular to the third end face between the first portion and the third end face.

[0058] (Supplementary Note 6) The wavelength-tunable laser device according to any one of Supplementary Notes 1 to 5, wherein the fourth waveguide includes a third portion inclined with respect to the fourth end face, a fourth portion extending from the third portion in a direction perpendicular to the fourth end face, and a fifth portion extending from the fourth portion toward a fifth end face opposite the fourth end face at an incline with respect to the fifth end face, and the laser light is emitted from the fifth portion via the fifth end face.

[0059] (Supplementary Note 7) The wavelength tunable laser device according to Supplementary Note 6, wherein the third portion and the fifth portion are inclined in the same direction with respect to the fourth end face and the fifth end face.

[0060] (Supplementary Note 8) The wavelength tunable laser device according to any one of Supplementary Notes 1 to 7, wherein the first waveguide includes a sixth portion inclined with respect to the first end face and a seventh portion extending in a direction perpendicular to the first end face between the sixth portion and the wavelength tunable filter, and the second waveguide includes an eighth portion inclined with respect to the first end face and a ninth portion extending in a direction perpendicular to the first end face between the eighth portion and the wavelength tunable filter.

[0061] (Supplementary Note 9) The wavelength tunable laser device according to any one of Supplementary Notes 1 to 8, wherein the reflecting means is a total reflection mirror that reflects the light incident from the third waveguide.

[0062] (Supplementary Note 10) A method for configuring a wavelength tunable laser device, comprising: a tunable optical resonator having a tunable filter capable of adjusting the wavelength of output light, the tunable optical resonator having first and second waveguides including portions inclined with respect to the first end face so as to be spaced apart from each other from the tunable filter toward a first end face; a first optical amplifier having a third waveguide including an active region provided between a second end face facing the first end face and a third end face opposite the second end face on which reflecting means is provided, the third waveguide including a portion inclined with respect to the second end face so as to be coaxial with the first waveguide; and a second optical amplifier configured to amplify the laser light propagating through the fourth waveguide, the laser light being oscillated by a resonator configured between the tunable filter and the reflecting means, and being input via a fourth end face facing the first end face to a fourth waveguide including a portion inclined with respect to the fourth end face so as to be coaxial with the second waveguide and to be coaxial with the second waveguide. [Explanation of symbols]

[0063] 1, 4 Tunable optical resonator 1A, 2A, 2B, 3A, 3B, 4A, 5A, 5B End face 2. SOA 3, 5 BOA 10, 40 wavelength tunable filter 11, 12, 21, 31, 41, 42, 51 straight waveguide 13, 14, 22, 32, 33, 43, 44, 52, 53 Inclined waveguide 23 Total reflection mirror 100 Tunable wavelength laser device 900 General wavelength tunable laser device

Claims

1. a tunable optical resonator having a tunable filter capable of adjusting the wavelength of output light, the tunable optical resonator having first and second waveguides including portions inclined with respect to the first end face so as to be spaced apart from each other from the tunable filter toward the first end face; a first optical amplifier having a third waveguide including an active region, the third waveguide including a portion extending from the second end face at an angle with respect to the second end face so as to be coaxial with the first waveguide, the third waveguide being provided between a second end face facing the first end face and a third end face opposite the second end face provided with a reflecting means; a second optical amplifier configured to amplify the laser light propagating through the fourth waveguide, wherein the laser light oscillated by a resonator configured between the wavelength tunable filter and the reflecting means and adjusted to a desired wavelength by the wavelength tunable filter is input via a fourth end face facing the first end face to a fourth waveguide including a portion extending from the fourth end face at an angle with respect to the fourth end face so as to be coaxial with the second waveguide, Tunable wavelength laser device.

2. the first waveguide is inclined with respect to the first end face in a first direction parallel to the end face, the second waveguide is tilted in a second direction opposite to the first direction; 2. The wavelength tunable laser device according to claim 1.

3. the first waveguide and the second waveguide are arranged symmetrically with respect to an axis perpendicular to the first end face; 3. The wavelength tunable laser device according to claim 2.

4. the portion of the third waveguide inclined with respect to the second end face and the portion of the fourth waveguide inclined with respect to the fourth end face are arranged symmetrically with respect to an axis perpendicular to the first end face.

3. The wavelength tunable laser device according to claim 1.

5. the third waveguide includes a first portion inclined with respect to the second end face, and a second portion extending between the first portion and the third end face in a direction perpendicular to the third end face; 3. The wavelength tunable laser device according to claim 1.

6. the fourth waveguide includes a third portion inclined with respect to the fourth end face; a fourth portion extending from the third portion in a direction perpendicular to the fourth end face; a fifth portion extending from the fourth portion toward a fifth end face opposite to the fourth end face and at an angle with respect to the fifth end face, the laser light is emitted from the fifth portion through the fifth end face; 3. The wavelength tunable laser device according to claim 1.

7. the third portion and the fifth portion are inclined in the same direction with respect to the fourth end face and the fifth end face; 7. The wavelength tunable laser device according to claim 6.

8. the first waveguide includes a sixth portion inclined with respect to the first end face, and a seventh portion extending in a direction perpendicular to the first end face between the sixth portion and the tunable filter, the second waveguide includes an eighth portion inclined with respect to the first end face, and a ninth portion extending in a direction perpendicular to the first end face between the eighth portion and the tunable filter.

3. The wavelength tunable laser device according to claim 1.

9. the reflecting means is a total reflection mirror that reflects the light incident from the third waveguide; 3. The wavelength tunable laser device according to claim 1.

10. a tunable optical resonator having a tunable filter capable of adjusting the wavelength of output light, the tunable optical resonator having first and second waveguides including portions inclined with respect to the first end face so as to be spaced apart from each other from the tunable filter toward the first end face; a first optical amplifier having a third waveguide including an active region, the third waveguide including a portion extending from the second end face at an angle with respect to the second end face so as to be coaxial with the first waveguide, the third waveguide being provided between a second end face facing the first end face and a third end face opposite the second end face on which a reflecting means is provided; a second optical amplifier is provided, in which laser light oscillated by a resonator configured between the wavelength tunable filter and the reflecting means and adjusted to a desired wavelength by the wavelength tunable filter is input, via a fourth end face facing the first end face, to a fourth waveguide including a portion extending from the fourth end face at an angle with respect to the fourth end face so as to be coaxial with the second waveguide, and the laser light propagating through the fourth waveguide is amplified; A method for configuring a wavelength tunable laser device.

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