Wavelength variable laser

Abstract

To provide a wavelength variable laser including an optical element that splits an optical path in order to couple an optical amplification waveguide to a semiconductor optical amplifier for lasers.SOLUTION: There is provided a wavelength variable laser which includes a semiconductor optical amplification element arranged in such a way that both ends of a first optical amplification waveguide that amplifies light by using a semiconductor are on the same element end surface that is an anti-reflection termination surface, two optical waveguide elements connected to both ends of the first optical amplification waveguide on the element end surface, and a first 2×2 branching unit, the two optical waveguide elements being connected to two ports on one side of the first 2×2 branching unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to tunable lasers. [Background technology]

[0002] A waveguide-type tunable laser formed on a semiconductor chip has been developed. Patent Document 1 discloses a waveguide-type tunable laser including a first reflector that outputs a laser, a second reflector that configures a laser resonator together with the first reflector, and a gain section provided between the first reflector and the second reflector. In the tunable laser, a waveguide is formed between the first reflector and the second reflector such that the optical path is turned back at an angle of substantially 180 degrees. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 156226 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is no disclosure of connecting the tunable laser with a further optical amplification waveguide to further increase the optical output intensity of the tunable laser or to adjust the optical output intensity to a desired value. Therefore, an object of the present disclosure is to provide a tunable laser including an optical element that branches an optical path to couple the optical amplification waveguide to the waveguide-type tunable laser. [Means for solving the problem]

[0005] The tunable laser of the present disclosure comprises: a semiconductor optical amplifier element arranged such that both ends of a first optical amplification waveguide for amplifying light by a semiconductor are located on the same element end face which is a non-reflective termination face; two optical waveguide elements each connected to both ends of the first optical amplification waveguide at the element end faces; The two optical waveguide elements are tunable lasers connected to two ports on one side of a first 2×2 branch. Effect of the Invention

[0006] The present disclosure provides a tunable laser having an optical element that branches an optical path to couple an optical amplification waveguide to a semiconductor optical amplifier for laser. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a configuration of a wavelength tunable laser according to a first embodiment; [Diagram 2] 1 is a schematic diagram showing a configuration of a wavelength tunable laser according to a first embodiment. [Diagram 3] FIG. 11 is a schematic diagram showing a configuration of a wavelength tunable laser according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the invention according to the claims is not limited to the following embodiment. Furthermore, not all of the configurations described in the embodiment are necessarily essential as means for solving the problem. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and repeated explanations are omitted as necessary.

[0009] (Description of Tunable Laser According to First Embodiment) Fig. 1 is a block diagram showing a configuration of a tunable laser according to a first embodiment. Fig. 2 is a schematic diagram showing a configuration of a tunable laser according to the first embodiment. The tunable laser according to the first embodiment will be described with reference to Figs. 1 and 2. The tunable laser 100 is a semiconductor laser capable of changing the wavelength.

[0010] 1 and 2, the tunable laser 100 includes a semiconductor optical amplifier having a first optical amplification waveguide 101, two optical waveguide elements 102, and a first 2×2 branching section 103. As shown in FIG. 2, the tunable laser 100 further includes a reflective tunable filter 104 and a second optical amplification waveguide 105.

[0011] The first optical amplification waveguide 101 is a semiconductor optical amplifier for laser formed in the semiconductor chip 106 for oscillating laser light. The laser light is, for example, infrared light having a wavelength of about 1500 nm. The first optical amplification waveguide 101 is U-shaped and arranged so that both ends are on the same element end face of the semiconductor chip 106. The element end face is an anti-reflection termination end face (AR (Anti-Reflection)).

[0012] The two optical waveguide elements 102 are connected at their element end faces to both ends of the first optical amplification waveguide 101. The two optical waveguide elements 102 transmit laser light that is incident on the first optical amplification waveguide 101 or that is emitted from the first optical amplification waveguide 101.

[0013] The first 2×2 branching unit 103 is a branching unit having two ports on one side arranged at both ends. The two ports on one side of the first 2×2 branching unit 103 are connected to two optical waveguide elements 102.

[0014] With this configuration, a tunable laser is provided that includes an optical element that branches an optical path to couple the semiconductor optical amplifier for laser use to the optical amplification waveguide. In addition, since the semiconductor optical amplifier for laser use is coupled in a U-shape, the laser light can be amplified without excessive optical loss due to the configuration.

[0015] Furthermore, one of the other two ports on the first 2×2 splitter 103 is connected to a reflective tunable filter 104. The reflective tunable filter 104 selects and reflects the wavelength of the incident laser light. Therefore, the laser light travels back and forth between the U-shaped first optical amplification waveguide 101 and the reflective tunable filter 104, and is amplified.

[0016] In this case, the first 2×2 splitting section 103 does not split at 50%. If it did split at 50%, all the light inside the laser resonator would be incident on the reflective tunable filter 104, and the laser light would not be able to be extracted outside the laser resonator. Therefore, it is preferable that the first 2×2 splitting section 103 is a directional coupler that can adjust the split ratio to a value other than 50%.

[0017] The other of the two ports on the other side of the first 2×2 branching section 103 is connected to a second optical amplification waveguide 105. The second optical amplification waveguide 105 is a semiconductor optical amplifier for optical output that uses a semiconductor to amplify laser light. Non-reflective termination end faces are formed on both ends of the second optical amplification waveguide 105. Therefore, the laser light incident on one side of the second optical amplification waveguide 105 is amplified by the second optical amplification waveguide 105 and is output from the other side of the second optical amplification waveguide 105.

[0018] The semiconductor chip 106 is composed of an optical amplification waveguide that generates optical gain by current injection and is formed using GaAs and desired impurities (Al, P, etc.) on a substrate of a semiconductor material such as InP. The second optical amplification waveguide 105 is formed in the same semiconductor chip 106 as the first optical amplification waveguide 101. By forming the second optical amplification waveguide 105 in the same semiconductor chip 106 as the first optical amplification waveguide 101, the wavelength tunable laser can be made smaller. Furthermore, by forming the second optical amplification waveguide 105 in the same semiconductor chip 106 as the first optical amplification waveguide 101, light of the same wavelength can be efficiently amplified.

[0019] (Description of a tunable laser according to the second embodiment) 3 is a schematic diagram showing a configuration of a wavelength tunable laser according to the second embodiment. The wavelength tunable laser according to the second embodiment will be described with reference to FIG.

[0020] 3, the tunable laser 300 includes a semiconductor optical amplifier having a first optical amplification waveguide 301, two optical waveguide elements 302, and a first 2×2 branching section 303. The tunable laser 300 further includes a reflective tunable filter 304 and a second optical amplification waveguide 305.

[0021] The tunable laser 300 further includes a semiconductor optical amplifier element including a third optical amplification waveguide 306, two optical waveguide elements 307, and a second 2×2 branching section 308. The tunable laser 300 further includes a reflective tunable filter 309 and a fourth optical amplification waveguide 310.

[0022] The first optical amplification waveguide 301, two optical waveguide elements 302, and first 2×2 branching section 303 of the tunable laser 300 are the same optical elements as the first optical amplification waveguide 101, two optical waveguide elements 102, and first 2×2 branching section 103 of the tunable laser 100, respectively. Also, the reflective tunable filter 304 and second optical amplification waveguide 305 of the tunable laser 300 are the same as the reflective tunable filter 104 and second optical amplification waveguide 105 of the tunable laser 100. Therefore, a description thereof will be omitted.

[0023] The third optical amplification waveguide 306 is a semiconductor optical amplifier for laser, the same as the first optical amplification waveguide 101. The second 2×2 branching section 308 is a branching section the same as the first 2×2 branching section 103. The second 2×2 branching section 308 does not branch at 50%. The second 2×2 branching section 308 is preferably a directional coupler that can adjust the branching ratio to a value other than 50%. Both ends of the third optical amplification waveguide 306 are connected to two ports on one side of the second 2×2 branching section 308 via two optical waveguide elements 307.

[0024] The fourth optical amplification waveguide 310 is a semiconductor optical amplifier for optical output, the same as the second optical amplification waveguide 105. Therefore, one end of the fourth optical amplification waveguide 310 is connected to the other of the two ports on the other side of the second 2×2 branching section 308. In addition, the other end of the fourth optical amplification waveguide 310 is connected to the non-reflection termination end face. Therefore, the laser light incident on one end of the fourth optical amplification waveguide 310 is amplified in the fourth optical amplification waveguide 310 and is output from the other end of the fourth optical amplification waveguide 310.

[0025] The reflective tunable filter 309 is the same as the reflective tunable filter 104. Therefore, one of the two ports on the other side of the second 2×2 branching unit is connected to the reflective tunable filter 309.

[0026] The third optical amplification waveguide 306 and the fourth optical amplification waveguide 310 are formed on the same semiconductor chip 311 as the first optical amplification waveguide 301 and the second optical amplification waveguide 305. With this configuration, the multi-channel wavelength tunable laser 300 can be formed on the same semiconductor chip 311. Therefore, the wavelength tunable laser 300 can be made compact.

[0027] The present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit and scope of the present invention. For example, if the connection of the optical elements constituting the second embodiment is the same as the connection of the optical elements constituting the first embodiment, it is within the scope of the present disclosure.

[0028] A part or all of the above-described embodiments can be described as follows, but is not limited to the following. (Appendix 1) a semiconductor optical amplifier element arranged such that both ends of a first optical amplification waveguide for amplifying light by a semiconductor are located on the same element end face which is a non-reflective termination end face; two optical waveguide elements each connected to both ends of the first optical amplification waveguide at the element end faces; a first 2×2 branch; The two optical waveguide elements are connected to two ports on one side of the first 2×2 branching section, and the .... (Appendix 2) 2. The tunable laser according to claim 1, wherein one of the two ports on the other side of the first 2×2 branching unit is connected to a reflective tunable filter. (Appendix 3) 2. The tunable laser according to claim 1, wherein the other of the two ports on the other side of the first 2×2 branching section is connected to one end of a second optical amplification waveguide. (Appendix 4) the first optical amplification waveguide is a semiconductor optical amplifier for laser; 4. The tunable laser according to claim 3, wherein the second optical amplification waveguide is a semiconductor optical amplifier for optical output. (Appendix 5) 4. The tunable laser according to claim 3, wherein the first optical amplification waveguide is formed in a same semiconductor chip as the second optical amplification waveguide. (Appendix 6) 6. The tunable laser according to claim 5, wherein the other end of the second optical amplification waveguide is connected to a non-reflection termination facet of the semiconductor chip. (Appendix 7) 2. The tunable laser according to claim 1, wherein the first 2×2 splitting section does not split at 50%. (Appendix 8) 2. The tunable laser according to claim 1, wherein the first 2×2 branching section is a directional coupler. (Appendix 9) the semiconductor chip includes a third optical amplification waveguide and a fourth optical amplification waveguide; the third optical amplification waveguide is connected at both ends to one of two ports of the second 2×2 branching section; 6. The tunable laser according to claim 5, wherein one end of the fourth optical amplification waveguide is connected to the other of the two ports on one side of the other of the second 2×2 branching section. (Appendix 10) 10. The tunable laser according to claim 9, wherein one of the two ports on the other side of the second 2×2 branching unit is connected to a reflective tunable filter. (Appendix 11) the third optical amplification waveguide is a semiconductor optical amplifier for laser; 10. The tunable laser according to claim 9, wherein the fourth optical amplification waveguide is a semiconductor optical amplifier for optical output. (Appendix 12) 10. The tunable laser according to claim 9, wherein the other end of the third optical amplification waveguide is connected to the non-reflection termination end face of the semiconductor chip. (Appendix 13) 10. The tunable laser according to claim 9, wherein the second 2×2 splitting section does not split at 50%. (Appendix 14) 10. The tunable laser according to claim 9, wherein the second 2×2 branching section is a directional coupler. [Explanation of symbols]

[0029] 100 Tunable laser, 101 First optical amplification waveguide, 102 Two optical waveguide elements, 103 First 2×2 branching section, 104 Reflective tunable filter, 105 Second optical amplification waveguide, 300 Tunable laser, 301 First optical amplification waveguide, 302 Two optical waveguide elements, 303 First 2×2 branching section, 304 Reflective tunable filter, 305 Second optical amplification waveguide, 306 Third optical amplification waveguide, 307 Two optical waveguide elements, 308 Second 2×2 branching section, 309 Reflective tunable filter, 310 Fourth optical amplification waveguide

Claims

1. a semiconductor optical amplifier element arranged such that both ends of a first optical amplification waveguide for amplifying light by a semiconductor are located on the same element end face which is a non-reflection termination end face; two optical waveguide elements each connected at an end surface of the element to both ends of the first optical amplification waveguide; a first 2×2 branch; The two optical waveguide elements are connected to two ports on one side of the first 2×2 branching section.

2. 2. The tunable laser according to claim 1, wherein one of the two ports on the other side of the first 2×2 branching section is connected to a reflective tunable filter.

3. 2. The tunable laser according to claim 1, wherein the other of the two ports on the other side of the first 2×2 branching section is connected to one end of a second optical amplification waveguide.

4. the first optical amplification waveguide is a semiconductor optical amplifier for laser; 4. The tunable laser according to claim 3, wherein the second optical amplification waveguide is a semiconductor optical amplifier for optical output.

5. 4. The tunable laser according to claim 3, wherein the first optical amplification waveguide and the second optical amplification waveguide are formed in the same semiconductor chip.

6. 6. The tunable laser according to claim 5, wherein the other end of said second optical amplification waveguide is connected to a non-reflection termination facet of said semiconductor chip.

7. The tunable laser of claim 1 , wherein the first 2×2 splitting section does not split at 50%.

8. The tunable laser according to claim 1 , wherein the first 2×2 branch section is a directional coupler.

9. the semiconductor chip includes a third optical amplification waveguide and a fourth optical amplification waveguide; the third optical amplification waveguide is connected at both ends to one of two ports of the second 2×2 branching section, 6. The tunable laser according to claim 5, wherein one end of the fourth optical amplification waveguide is connected to the other of the two ports on one side of the other of the second 2×2 branching section.

10. 10. The tunable laser according to claim 9, wherein one of the two ports on the other side of the second 2×2 branching unit is connected to a reflective tunable filter.

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