Single longitudinal-mode optical fiber laser with low noise, narrow linewidth and high power

Abstract

The invention discloses a single longitudinal-mode optical fiber laser with low noise, narrow linewidth and high power. Polarization maintaining optical fiber is rare-earth-doped phosphate single-mode glass optical fiber, the component of a fiber core is phosphate glass which consists of 70P2O5-8Al2O3-15BaO-4La2O3-3Nd2O3, the fiber core of the polarization maintaining optical fiber is doped with high-concentration luminous ions, the luminous ions are one or combination of more than one of lanthanide ions and transition metal ions, the doping density of the luminous ions is greater than 1*10<19>ions / cm<3> and the luminous ions are evenly doped in the fiber core. A polarization maintaining fiber Bragg grating with the narrow linewidth and a dichroscope form a front cavity mirror and a rear cavity mirror of the optical fiber laser, a centimeter-sized erbium-ytterbium co-doped phosphate glass polarization maintaining optical fiber is taken as a laser working substance, and polarization maintaining output laser generated by a single-mode semiconductor laser is taken as a pumping source, thus achieving the single longitudinal-mode laser output by designing and manufacturing the reflection spectrum width of the polarization maintaining fiber Bragg grating and controlling the cavity length of the whole laser cavity.

Description

technical field

[0001] The invention relates to a fiber laser, in particular to a low-noise, narrow-linewidth, and high-power single-longitudinal-mode fiber laser. The linewidth of the laser reaches the KHz level, and the output power reaches the order of hundreds of mW. Background technique

[0002] Ultra-narrow linewidth single-frequency laser has a wide range of application prospects in industry, agriculture, military and other fields due to its excellent coherence performance, especially in long-distance, high-precision sensing, laser ranging and indication. To improve the detection distance or accuracy of fiber laser, it is necessary to use laser with high coherence performance. Therefore, the laser is required to have a spectral width with ultra-narrow linewidth. For example, a single-frequency fiber laser with KHz linewidth and mW level is required as a seed source. It is difficult to achieve high power (>100mW) and ultra-narrow linewidth (<2KHz) single-frequenc...

Examples

Embodiment 1

[0024] High-gain rare-earth-doped phosphate glass single-mode polarization-maintaining fiber 4 is used as the gain medium of the fiber laser. The length can be selected according to the laser output power of the device and the reflection spectral width of the narrow-linewidth polarization-maintaining fiber grating 3. In this example, it is 0.5 cm, generally 0.5 to 10 cm. The fiber core 9 is doped with high-concentration luminescent ions of erbium and ytterbium, and the doping concentrations of erbium and ytterbium rare earth ions are 2.5×10 20 ions / cm 3 , 5.0×10 20 ions / cm 3 , generally greater than 1×10 19 ions / cm 3 . Such as Figure 2a As shown, the cross-sectional structure of the core 9 of the rare earth-doped phosphate glass single-mode polarization-maintaining optical fiber 4 is elliptical, the ratio of the major axis to the minor axis is 1.2:1, generally 1.1-3.0:1, and the minor axis length is 5 μm. Generally, it can be 1-10 μm, and the cladding layer 8 is circul...

Embodiment 2

[0028] High-gain rare-earth-doped phosphate glass single-mode polarization-maintaining fiber 4 is used as the gain medium of the fiber laser. The length can be selected according to the laser output power of the device and the reflection spectral width of the narrow-linewidth polarization-maintaining fiber grating 3. In this example, it is 0.8 cm, generally 0.5 to 10 cm. The fiber core 9 is doped with high-concentration luminescent ions of ytterbium, and the doping concentration of ytterbium rare earth ions is 7.5×10 20 ions / cm 3 , generally greater than 1×10 19 ions / cm 3 . Such as Figure 2b As shown, the rare earth-doped phosphate glass single-mode polarization-maintaining optical fiber 4 has a cross-sectional structure of a panda structure, the fiber core 9 is circular, and its diameter is 8 μm, generally 1-10 μm. Consistent, the distance from the fiber core 9 is 20-40 μm, the diameter of the cat’s eye 10 is 15 μm, generally 10-20 μm is acceptable, the cladding 8 is ci...

Embodiment 3

[0032] The high-gain rare-earth-doped phosphate glass single-mode polarization-maintaining fiber 4 has a length of 10 cm, and the fiber core 9 is doped with high-concentration luminescent ions that are transition metal ions Cu. 2+ , Cu 2+ The doping concentrations are 1.5×10 19 ions / cm 3. Others are with embodiment 2. Similarly, the core 9 doped with a high concentration of luminescent ions is Co 2+ 、Cr 3+ , Fe 2+ or Mn 2+ transition metal ions.

technical field

[0001] The invention relates to a fiber laser, in particular to a low-noise, narrow-linewidth, and high-power single-longitudinal-mode fiber laser. The linewidth of the laser reaches the KHz level, and the output power reaches the order of hundreds of mW. Background technique

[0002] Ultra-narrow linewidth single-frequency laser has a wide range of application prospects in industry, agriculture, military and other fields due to its excellent coherence performance, especially in long-distance, high-precision sensing, laser ranging and indication. To improve the detection distance or accuracy of fiber laser, it is necessary to use laser with high coherence performance. Therefore, the laser is required to have a spectral width with ultra-narrow linewidth. For example, a single-frequency fiber laser with KHz linewidth and mW level is required as a seed source. It is difficult to achieve high power (>100mW) and ultra-narrow linewidth (<2KHz) single-frequenc...

Examples

Embodiment 1

[0024] High-gain rare-earth-doped phosphate glass single-mode polarization-maintaining fiber 4 is used as the gain medium of the fiber laser. The length can be selected according to the laser output power of the device and the reflection spectral width of the narrow-linewidth polarization-maintaining fiber grating 3. In this example, it is 0.5 cm, generally 0.5 to 10 cm. The fiber core 9 is doped with high-concentration luminescent ions of erbium and ytterbium, and the doping concentrations of erbium and ytterbium rare earth ions are 2.5×10 20 ions / cm 3 , 5.0×10 20 ions / cm 3 , generally greater than 1×10 19 ions / cm 3 . Such as Figure 2a As shown, the cross-sectional structure of the core 9 of the rare earth-doped phosphate glass single-mode polarization-maintaining optical fiber 4 is elliptical, the ratio of the major axis to the minor axis is 1.2:1, generally 1.1-3.0:1, and the minor axis length is 5 μm. Generally, it can be 1-10 μm, and the cladding layer 8 is circul...

Embodiment 2

[0028] High-gain rare-earth-doped phosphate glass single-mode polarization-maintaining fiber 4 is used as the gain medium of the fiber laser. The length can be selected according to the laser output power of the device and the reflection spectral width of the narrow-linewidth polarization-maintaining fiber grating 3. In this example, it is 0.8 cm, generally 0.5 to 10 cm. The fiber core 9 is doped with high-concentration luminescent ions of ytterbium, and the doping concentration of ytterbium rare earth ions is 7.5×10 20 ions / cm 3 , generally greater than 1×10 19 ions / cm 3 . Such as Figure 2b As shown, the rare earth-doped phosphate glass single-mode polarization-maintaining optical fiber 4 has a cross-sectional structure of a panda structure, the fiber core 9 is circular, and its diameter is 8 μm, generally 1-10 μm. Consistent, the distance from the fiber core 9 is 20-40 μm, the diameter of the cat’s eye 10 is 15 μm, generally 10-20 μm is acceptable, the cladding 8 is ci...

Embodiment 3

[0032] The high-gain rare-earth-doped phosphate glass single-mode polarization-maintaining fiber 4 has a length of 10 cm, and the fiber core 9 is doped with high-concentration luminescent ions that are transition metal ions Cu. 2+ , Cu 2+ The doping concentrations are 1.5×10 19 ions / cm 3. Others are with embodiment 2. Similarly, the core 9 doped with a high concentration of luminescent ions is Co 2+ 、Cr 3+ , Fe 2+ or Mn 2+ transition metal ions.

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