# US 2016/0261085 A1 · Tunable Narrow-Linewidth Single-Frequency Linear-Polarization Laser Device

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- Number: US 2016/0261085 A1
- Document ID: US20160261085A1
- Status: Published application
- Kind: A1
- Application number: 15/035,605
- Filed: 2014-12-04
- Published: 2016-09-08
- Earliest claimed: 2014-01-17
- Assignees: South China University of Technology
- Applicants: South China University of Technology
- Inventors: Shanhui Xu; Changsheng Yang; Zhongmin Yang; Zhouming Feng; Qinyuan Zhang; Zhonghong Jiang
- Web page: https://patentgrep.com/patent/US20160261085A1

## CPC

- H01S 3/1055: one of the reflectors being constituted by a diffraction grating
- H01S 3/0405: {Conductive cooling, e.g. by heat sinks or thermo-electric elements}
- H01S 3/06712: {Polarising fibre; Polariser}
- H01S 3/06716: {Fibre compositions (per se C03C13/04)or doping with active elements (lasing materials in general H01S3/14)}
- H01S 3/0675: {Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers}
- H01S 3/094042: {of a fibre laser}
- H01S 3/1028: {by controlling the temperature}
- H01S 3/1062: {using a controlled passive interferometer, e.g. a Fabry-Perot etalon}
- H01S 3/137: for stabilising of frequency
- H01S 3/139: by controlling the mutual position or the reflecting properties of the reflectors of the cavity {, e.g. by controlling the cavity length}
- H01S 3/1603: {rare earth}
- H01S 3/0064: {Anti-reflection devices, e.g. optical isolaters (absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955)}
- H01S 3/0401: {of optical elements being part of laser resonator, e.g. windows, mirrors, lenses}
- H01S 3/06708: {Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering (optical fibres as passive waveguides G02B6/02)}
- H01S 3/08027: {by a filter, e.g. a Fabry-Perot filter is used for wavelength setting}
- H01S 3/1618: {ytterbium}
- H01S 3/175: {phosphate glass}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

A tunable narrow-linewidth single-frequency linear-polarization laser device comprising a heat sink, a pumping source packaged on the heat sink, a first and second collimating lenses, a laser back cavity mirror, a thermal optical tunable filter, a rare-earth-ion heavily-doped multicomponent glass optical fiber, a super-structure polarization-maintaining fiber grating, a polarization-maintaining optical isolator, a polarization-maintaining optical fiber, and a thermoelectric refrigerating machine. The laser device uses a short and straight single-frequency resonant cavity structure, the heavily-doped and high-gain characteristics of the multicomponent glass optical fiber, a frequency selection role and wavelength tuning function of the thermal optical tunable filter and the superstructure polarization-maintaining fiber grating, and combines a precision temperature adjustment technology, and by means of real-time adjustment of distribution of reflection wavelengths and transmission wavelengths, the laser device changes spectrum peak overlapping positions, so as to implement stable output of wide-tuning-range, extra-narrow-linewidth, high-extinction-ratio and high-output-power continuously tunable single-frequency linear-polarization laser.

## Claims

### Claim 1

A tunable narrow-linewidth single-frequency linear-polarization laser device, characterized in that, comprising: a heat sink, a pumping source packaged on the heat sink, a first collimating lens, a laser back cavity mirror, a thermal optical tunable filter, a second collimating lens, a rare-earth-ion heavily-doped multicomponent glass optical fiber, a super-structure polarization-maintaining fiber grating, a polarization-maintaining optical isolator, a polarization-maintaining optical fiber, and a thermoelectric cooler TEC; wherein the pumping source, the first collimating lens, the laser back cavity mirror, the thermal optical tunable fiber, the second collimating lens, the rare-earth-ion heavily-doped multicomponent glass optical fiber, the super-structure polarization-maintaining fiber grating, the polarization-maintaining optical isolator, the polarization-maintaining optical fiber being arranged in sequence, and the pumping source, the thermal optical tunable filter and the super-structure polarization-maintaining fiber grating each being arranged on a thermoelectric cooler TEC.

### Claim 2 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the output of the pumping source being coupled with the laser back cavity mirror via the first collimating lens, the laser back cavity mirror being coupled with the thermal optical tunable filter, the thermal optical tunable filter being coupled with the second collimating lens, the second collimating lens being coupled with the input of the rare-earth-ion heavily-doped multicomponent glass optical fiber, the output of the rare-earth-ion heavily-doped multicomponent glass optical fiber being coupled with the input of the super-structure polarization-maintaining fiber grating, the output of the super-structure polarization-maintaining fiber grating being coupled with the input of the polarization-maintaining optical fiber, the output of the polarization-maintaining optical fiber being coupled with the tail fiber of the polarization-maintaining optical fiber.

### Claim 3 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the laser back cavity mirror being coated with thin membrane layer on its mirror terminal surface, the thin membrane layer highly reflecting the laser signal wavelengths more than 80% and highly transmitting the pumping source wavelengths more than 80%.

### Claim 4 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the thermal optical tunable filter being an F-P type membrane tunable filter; the thermoelectric cooler TEC performing precise temperature control and the thermal optical characteristics and the high refraction ratio of the intermediate membrane material of the filter being used, such that the refraction ratio of the intermediate membrane material of the filter being varied to implement the tenability of the transmission wavelengths.

### Claim 5 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the fiber core component of the rare-earth-ion heavily-doped multicomponent glass optical fiber being phosphate glass components, which is 65P2O5-10Al2O3-20BaO-3La2O3-2Nd2O3; the fiber core of the rare-earth-ion heavily-doped multicomponent glass optical fiber were evenly doped with high concentration of rare earth luminescence ions, the doping concentration of the rare earth luminescence ions being more than 1×1020 ions/cm3; the rare earth luminescence ions including one or more of lanthanide ions, alkaline earth metal ions, transition metal ions or their combinations.

### Claim 6 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the shape of the fiber core of the rare-earth-ion heavily-doped multicomponent glass optical fiber being circle with a fiber core diameter of 3˜50 μm; the shape of the wrapping layer being circle, D-shape, hexagon, or octagon, wherein the diameter of the circular wrapping layer or the side-to-side distance of the non-circular wrapping layer being 80˜900 μm.

### Claim 7 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein one end of the rare-earth-ion heavily-doped multicomponent glass optical fiber being coated with a multi-layer antireflection coating, wherein the multi-layer antireflection coating highly transmitting the laser signal wavelengths with a transmission ratio of more than 90% to suppress the reflection of the fiber terminal surface.

### Claim 8 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the super-structure polarization-maintaining fiber grating selectively comb reflecting the laser signal wavelengths which is partial transmission with a reflection ratio of the center wavelength being 20%˜80%, having a good characteristic of uniformity of the reflection peaks and a narrow bandwidth as a coupling component for laser output.

### Claim 9 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization 1 laser device according to claim 1, wherein the pumping source being a semiconductor laser device with an edge emitting structure or other form of package; wherein the output mode of the 1 pumping source being either single-mode or multi-mode, the outputting parameters of the pumping wavelength being 800˜1200 nm and the outputting pumping source being more than 50 mW; the pumping mode of the pumping source being forward pumping, that is, the pumping light emitted from the pumping source coupling directly through the collimating lens into the optical path.

### Claim 10 (depends on 1)

The tunable narrow-linewidth single-frequency linear-polarization laser device according to claim 1, wherein the temperature of the thermal optical tunable filter and the super-structure polarization-maintaining fiber grating being precisely controlled by independent thermoelectric cooler TEC, constituting the laser device wavelength/frequency tenability function section; the precise temperature control causing the refraction ratio of the fiber grating and the filter vary accordingly such that the coupling overlapping positions of the gate reflection spectrum of the super-structure polarization-maintaining fiber grating and the transmission spectrum of the thermal optical tunable filter continuously varying to achieve an optical fiber frequency selection with the most feedback gain at different wavelengths, that is, to implement wide-tuning-range continuously tunable output wavelengths of the single-frequency linear-polarization laser device.