Semiconductor optical amplification element

Abstract

To provide a semiconductor optical amplification element suitable for a wavelength variable laser.SOLUTION: A semiconductor optical amplification element includes: a first optical amplification waveguide that amplifies light by using a semiconductor; a second optical amplification waveguide that amplifies light by using the semiconductor; and a loop waveguide reflector that reflects light by using a loop of a waveguide. One end of the first optical amplification waveguide is connected to the loop waveguide reflector. Another end of the first optical amplification waveguide and another end of the second optical amplification waveguide are formed with a coplanar anti-reflection termination surface, and one end of the second optical amplification waveguide is formed with an anti-reflection termination surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor optical amplifier. [Background technology]

[0002] As semiconductor optical amplifiers for wavelength tunable lasers, SOAs (Semiconductor Optical Amplifiers) for laser oscillation and SOAs for optical amplification (sometimes called BOA (Booster Optical Amplifiers) to distinguish them from SOAs for laser oscillation) are used. FIG. 7 of Patent Document 1 discloses an optical integrated device that includes a first SOA and a second SOA, with a waveguide-type mirror connected to the first SOA. Here, the waveguide-type mirror is a diffraction grating mirror. The role of the first SOA is for laser oscillation, and the role of the second SOA is for optical amplification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-98362 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the diffraction grating mirror connected to the first SOA for laser oscillation has wavelength dependency and is not suitable for use in achieving optical gain for achieving laser oscillation in a wide wavelength band, such as in a wavelength tunable laser. In principle, the diffraction grating mirror cannot reflect all of the spontaneous emission light of the first SOA, and is designed to reflect only a limited wavelength band (the wavelength band used in the wavelength tunable laser). Therefore, the spontaneous emission light of the first SOA outside the wavelength band used is not reflected and is emitted outside the chip, becoming stray light and hindering the operation of the wavelength tunable laser. Therefore, the object of the present disclosure is to provide a semiconductor optical amplifier suitable for a wavelength tunable laser. [Means for solving the problem]

[0005] The semiconductor optical amplifier of the present disclosure comprises: a first optical amplification waveguide that amplifies light using a semiconductor; a second optical amplification waveguide that amplifies light using the semiconductor; and a loop waveguide type reflector that reflects light using a loop of a waveguide; one end of the first optical amplification waveguide is connected to the loop waveguide type reflector; the other end of the first optical amplification waveguide and the other end of the second optical amplification waveguide are formed with a non-reflection termination facet that is in the same plane; One of the second optical amplification waveguides is a semiconductor optical amplifier element having a non-reflective termination facet. Effect of the Invention

[0006] The present disclosure provides a semiconductor optical amplifier suitable for a wavelength tunable laser. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a configuration of a semiconductor optical amplifier according to an embodiment; [Diagram 2] 1 is a schematic diagram showing a configuration of a semiconductor optical amplifier according to an 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 Semiconductor Optical Amplification Device According to an Embodiment) Fig. 1 is a block diagram showing a configuration of a semiconductor optical amplifier according to an embodiment. Fig. 2 is a schematic diagram showing a configuration of a semiconductor optical amplifier according to an embodiment. The semiconductor optical amplifier according to the embodiment will be described with reference to Figs. 1 and 2. Semiconductor optical amplifier 100 is an element that amplifies light using a semiconductor and emits laser light.

[0010] 1 and 2, the semiconductor optical amplifier 100 includes a first optical amplification waveguide 101 (SOA), a second optical amplification waveguide 102 (BOA), and a loop waveguide type reflector 103 in a semiconductor chip 105. Furthermore, as shown in FIG. 2, the semiconductor optical amplifier 100 includes a tunable filter 104 attached to the semiconductor chip 105.

[0011] The semiconductor chip 105 and the optical amplification waveguide are composed of, for example, a semiconductor such as InP or GaAs, and intentionally added impurities (such as Al or P). By forming the first optical amplification waveguide 101 and the second optical amplification waveguide 102 on the same semiconductor chip 105, the semiconductor optical amplifier 100 can be made compact. Furthermore, by forming the first optical amplification waveguide 101 and the second optical amplification waveguide 102 on the same semiconductor chip 105, a waveguide that can efficiently amplify light of the same wavelength can be formed.

[0012] The first optical amplification waveguide 101 is a semiconductor optical amplifier for laser oscillation that amplifies light using a semiconductor. The first optical amplification waveguide 101 is used to oscillate light with a wavelength near infrared light (wavelength of about 1500 nm), for example. One side of the first optical amplification waveguide 101 is connected to a loop waveguide type reflector. In addition, a non-reflection end face (AR (Anti-Reflection) film) is formed on the other side of the first optical amplification waveguide 101. The other side of the first optical amplification waveguide 101 is connected to a wavelength tunable filter 104. Therefore, light from the first optical amplification waveguide 101 passes through the non-reflection end face and enters the wavelength tunable filter 104. By forming an optical resonator in which only a specific wavelength is selected by the wavelength tunable filter 104 and returns to the first optical amplification waveguide 101 again, an optical gain greater than the internal loss of the optical resonator is realized in the first optical amplification waveguide 101, thereby performing laser oscillation. A laser using the first optical amplification waveguide 101 can change the wavelength of laser oscillation light by controlling and changing the wavelength selected by the wavelength tunable filter 104 .

[0013] The second optical amplification waveguide 102 is a semiconductor optical amplifier for optical output that uses a semiconductor to amplify a laser light partially extracted from a wavelength tunable laser using the first optical amplification waveguide 101. One side of the second optical amplification waveguide 102 is formed with a non-reflection end face. The other side of the second optical amplification waveguide 102 is formed with a non-reflection end face on the same plane as the first optical amplification waveguide 101. The other side of the second optical amplification waveguide 102 is connected to the first optical amplification waveguide 101. Therefore, the second optical amplification waveguide 102 amplifies the light incident from the other side while sending it in one direction. Laser light is emitted from one side of the second optical amplification waveguide 102.

[0014] The loop waveguide reflector 103 is an optical element that reflects light using a configuration in which the two output sides of a two-input two-output or one-input two-output directional coupler or a multi-mode interference (MMI (Multi-Mode-Interference)) waveguide are loop-connected with a waveguide. The internal light of the wavelength tunable laser travels back and forth inside the laser resonator formed by the reflectors in the loop waveguide reflector 103 and the wavelength tunable filter 104, and is internally amplified in the first optical amplification waveguide, resulting in laser oscillation. The light incident on the loop waveguide reflector 103 is branched into one and the other, and returns to the first optical amplification waveguide 101 through the waveguide. The loop waveguide reflector 103 can match the phase and multiplex the two paths after branching because the optical distances of the two paths are the same. Therefore, in order to maximize the reflectance, it is preferable that the intensity of each of the branched lights is 50%. Therefore, it is preferable to use an MMI waveguide that can reduce wavelength dependency for coupling between the loop waveguide type reflector 103 and the first optical amplification waveguide 101, but a directional coupler may also be used.

[0015] The tunable filter 104 is an optical element for changing the laser oscillation wavelength of the tunable laser using the first optical amplification waveguide 101 to an arbitrary wavelength. By arbitrarily selecting the wavelength of the laser light traveling back and forth between the first optical amplification waveguide 101 and the tunable filter 104, it is possible to realize single-mode laser oscillation at an arbitrary wavelength.

[0016] The above configuration provides a semiconductor optical amplifier suitable for a wavelength tunable laser.

[0017] The present invention is not limited to the above-mentioned embodiment, and can be modified as appropriate without departing from the spirit of the present invention. For example, in the present disclosure, the first optical amplification waveguide 101 and the second optical amplification waveguide 102 are formed on the same semiconductor chip 105. However, a third optical amplification waveguide which is a semiconductor optical amplifier for laser and a fourth optical amplification waveguide which is a semiconductor optical amplifier for optical output may be further formed on the same semiconductor chip 105.

[0018] A part or all of the above-described embodiments can be described as follows, but is not limited to the following. (Appendix 1) a first optical amplification waveguide that amplifies light using a semiconductor; a second optical amplification waveguide that amplifies light using the semiconductor; and a loop waveguide type reflector that reflects light using a loop of a waveguide; one end of the first optical amplification waveguide is connected to the loop waveguide type reflector; the other end of the first optical amplification waveguide and the other end of the second optical amplification waveguide are formed with a non-reflection termination facet that is in the same plane; a non-reflective termination facet is formed on one side of the second optical amplification waveguide, (Appendix 2) 2. The semiconductor optical amplifier according to claim 1, wherein the first optical amplification waveguide is formed in a same semiconductor chip as the second optical amplification waveguide. (Appendix 3) 2. The semiconductor optical amplifier according to claim 1, wherein the other of the first optical amplification waveguide is connected to a tunable filter. (Appendix 4) the first optical amplification waveguide is a semiconductor optical amplifier for laser; 2. The semiconductor optical amplifier according to claim 1, wherein the second optical amplification waveguide is a semiconductor optical amplifier for optical output. (Appendix 5) 5. The semiconductor optical amplifier according to claim 4, wherein the first optical amplification waveguide is connected to the second optical amplification waveguide. (Appendix 6) 2. The semiconductor optical amplifier according to claim 1, wherein the loop waveguide type reflector is connected to one side of the first optical amplification waveguide using a 1×2 directional coupler. (Appendix 7) 2. The semiconductor optical amplifier according to claim 1, wherein the loop waveguide type reflector is connected to one side of the first optical amplification waveguide using a 1×2 MMI (Multi-Mode-Interference) waveguide. [Explanation of symbols]

[0019] 100: semiconductor optical amplifier element; 101: first optical amplification waveguide; 102: second optical amplification waveguide; 103: loop waveguide type reflector; 104: wavelength tunable filter; 105: semiconductor chip.

Claims

1. a first optical amplification waveguide that amplifies light using a semiconductor; a second optical amplification waveguide that amplifies light using the semiconductor; a loop waveguide type reflector that reflects light using a loop of a waveguide; one end of the first optical amplification waveguide is connected to the loop waveguide type reflector; the other end of the first optical amplification waveguide and the other end of the second optical amplification waveguide are formed with a non-reflection termination end face that is in the same plane; a non-reflective termination facet is formed on one side of the second optical amplification waveguide;

2. 2. The semiconductor optical amplifier according to claim 1, wherein said first optical amplification waveguide and said second optical amplification waveguide are formed in the same semiconductor chip.

3. 2. The semiconductor optical amplifier according to claim 1, wherein the other of said first optical amplification waveguide is connected to a wavelength tunable filter.

4. the first optical amplification waveguide is a semiconductor optical amplifier for laser; 2. The semiconductor optical amplifier according to claim 1, wherein said second optical amplification waveguide is a semiconductor optical amplifier for optical output.

5. 5. The semiconductor optical amplifier according to claim 4, wherein said first optical amplification waveguide is connected to said second optical amplification waveguide.

6. 2. The semiconductor optical amplifier according to claim 1, wherein the loop waveguide type reflector is connected to one side of the first optical amplification waveguide by a 1.times.2 directional coupler.

7. 2. The semiconductor optical amplifier according to claim 1, wherein the loop waveguide type reflector is connected to one side of the first optical amplification waveguide by using a 1×2 MMI (Multi-Mode-Interference) waveguide.

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