CN-121978803-A - Target wave band output structure, laser output light source and gas detection system

Abstract

The application provides a target wave band output structure, a laser output light source and a gas detection system, and relates to the technical field of photoelectricity. The periodic polarized waveguide is arranged on the substrate, and the first optical signal and the second optical signal are transmitted in the periodic polarized waveguide; the reflective films are arranged at two ends of the periodically polarized waveguide along the first direction and reflect the first optical signals; the first directional coupler includes a first coupling waveguide and a first Bragg grating embedded in the first coupling waveguide. According to the scheme, the pump light is converted into the first optical signal and the second optical signal by the periodic polarized waveguide, the first optical signal is limited in the waveguide by the reflecting film, and meanwhile, the second optical signal is efficiently coupled and output from the periodic polarized waveguide by the first directional coupler embedded with the first Bragg grating, so that the separation of dual-band light is realized, the integration level is improved, and meanwhile, the process complexity is reduced.

Inventors

• SHI YUECHUN
• LI SHUAI

Assignees

• 甬江实验室

Dates

Publication Date

20260505

Application Date

20251224

Claims (10)

1. 1. A target band output structure, comprising: A substrate; The device comprises a substrate, a periodically polarized waveguide, a first optical signal and a second optical signal, wherein the periodically polarized waveguide is arranged on the substrate and is used for transmitting the first optical signal and the second optical signal, and the wavelength of the first optical signal is different from that of the second optical signal; Reflective films disposed at both ends of the periodically polarized waveguide in the first direction, the reflective films reflecting the first optical signal; The first directional coupler is arranged on the substrate, comprises a first coupling waveguide and a first Bragg grating embedded in the first coupling waveguide, and is positioned on one side of the periodic polarization waveguide along a second direction and is in coupling connection with the periodic polarization waveguide; Wherein the second optical signal is coupled to the first directional coupler by the periodically poled waveguide.
2. 2. The target band output structure of claim 1, wherein the periodically poled waveguide comprises a first sub-waveguide and two second sub-waveguides located on either side of the first sub-waveguide, the first sub-waveguide having a periodically poled structure, the second sub-waveguide being in an aperiodic poled state; Wherein the reflective films are disposed on two ends of the two second sub-waveguides that are far from each other; the first directional coupler is arranged on one side of one of the second sub-waveguides along the second direction.
3. 3. The target band output structure of claim 1, wherein the first directional coupler has an output, the second optical signal being output by the output of the first directional coupler; Wherein the target band output structure further comprises: and the antireflection film is arranged at the output end of the first directional coupler.
4. 4. The target band output structure of claim 1, wherein the first coupling waveguide includes a first sub-portion and two second sub-portions disposed at both ends of the first sub-portion, the first bragg grating is embedded in the first sub-portion, one of the two second sub-portions serves as an output end of the first directional coupler, and the other is disposed in a curved manner.
5. 5. The target band output structure of claim 1, further comprising: the second directional coupler is arranged on the substrate, and comprises a second coupling waveguide and a second Bragg grating embedded in the second coupling waveguide, wherein the second directional coupler is positioned on one side of the periodic polarization waveguide along a second direction and is in coupling connection with the periodic polarization waveguide; wherein the first directional coupler and the second directional coupler are respectively positioned at two ends of the periodically polarized waveguide.
6. 6. The target band output structure of claim 5, wherein the second directional coupler has an input for input by a light source; Wherein the target band output structure further comprises: The interface waveguide is arranged on the substrate and is connected with the input end of the second directional coupler, and the area of the cross section of the interface waveguide perpendicular to the substrate is gradually changed; a cladding layer disposed around the interface waveguide.
7. 7. The target band output structure of claim 1, further comprising: And the thin film resistor is arranged on one side of the periodically polarized waveguide along the second direction and/or on one side of the first Bragg grating away from the periodically polarized waveguide along the second direction.
8. 8. The target band output structure of claim 1, wherein the wavelength of the light output by the first directional coupler is 2.5-25 μm.
9. 9. A laser output light source, comprising: the target band output structure of any one of claims 1 to 8; and the laser is coupled and connected with the input end of the target wave band output structure.
10. 10. A gas detection system, comprising: a laser output light source as claimed in claim 9; and the detection chamber is used for introducing gas to be detected, and at least part of the laser output light source is positioned in the detection chamber.

Description

Target wave band output structure, laser output light source and gas detection system Technical Field The application relates to the technical field of photoelectricity, in particular to a target wave band output structure, a laser output light source and a gas detection system. Background Because a plurality of gases have unique and strong absorption fingerprint peaks in the mid-infrared wave band of 2.5-25 mu m, the mid-infrared light source has become an ideal choice for trace gas detection and is a core technology of high-precision gas sensing. However, the direct generation of efficient, widely tunable mid-infrared laser sources in this band remains a significant challenge. At present, the pump light can be converted into signal light and idler light by utilizing the nonlinear frequency conversion characteristic of periodically polarized lithium niobate (Periodically Poled Lithium Niobate, PPLN), wherein the idler light is the required mid-infrared band light source. However, when the idler light is output from the PPLN, a dual-wavelength coating is required to be performed on the output end of the PPLN, and the process is complex and has high cost. In order to avoid dual-wavelength coating, although a directional coupler can be used to couple idler light in the PPLN from the main waveguide to the output waveguide, the coupling effect of the traditional directional coupler is relatively weak. Disclosure of Invention The embodiment of the application provides a target wave band output structure, a laser output light source and a gas detection system, which aim to convert pump light into a first optical signal and a second optical signal by using a periodic polarized waveguide, limit the first optical signal in the waveguide by using a reflecting film, and simultaneously efficiently couple and output the second optical signal from the periodic polarized waveguide by using a first directional coupler embedded with a first Bragg grating, thereby realizing the separation of dual-wave band light, improving the integration level and reducing the process complexity. In order to achieve the above purpose, the embodiment of the present application adopts the following technical scheme: in a first aspect, a target band output structure is provided that includes a substrate, a periodically poled waveguide, a reflective film, and a first directional coupler. The periodic polarized waveguide is arranged on the substrate, a first optical signal and a second optical signal are transmitted in the periodic polarized waveguide, the wavelength of the first optical signal is different from that of the second optical signal, the periodic polarized waveguide extends along a first direction, and the first direction is parallel to the substrate. The reflective films are disposed at both ends of the periodically poled waveguide in a first direction, and reflect the first optical signal. The first directional coupler is arranged on the substrate, comprises a first coupling waveguide and a first Bragg grating embedded in the first coupling waveguide, and is positioned on one side of the periodic polarized waveguide along a second direction and is in coupling connection with the periodic polarized waveguide, and the second direction is parallel to the substrate and is mutually perpendicular to the first direction. The second optical signal is coupled to the first directional coupler by a periodically poled waveguide. In particular, the first optical signal may refer to signal light and the second optical signal may refer to idler light (i.e., mid-infrared light source). In the target band output structure provided by the embodiment of the application, the input pump light is efficiently converted into the first optical signal and the second optical signal by utilizing the nonlinear frequency conversion characteristic of the periodic polarization waveguide, the reflective film which only reflects the first optical signal is prepared at the two ends of the periodic polarization waveguide along the first direction, the first optical signal is limited in the periodic polarization waveguide, meanwhile, the first directional coupler embedded with the first Bragg grating is arranged at one side of the periodic polarization waveguide, and the second optical signal (namely, the mid-infrared light source) in the periodic polarization waveguide is efficiently coupled into the first coupling waveguide, so that the output of wavelength conversion and the mid-infrared light source is simultaneously realized on a single substrate, the integration level of the target band output structure is improved, the traditional dual-wavelength coating process is avoided, and the preparation cost and complexity are reduced. In some embodiments, the periodically poled waveguide includes a first sub-waveguide having a periodically poled structure and two second sub-waveguides located at opposite ends of the first sub-waveguide, the second sub-waveguide being i