An all-fiber ld-pumped multimode fiber cascaded Raman random laser

Abstract

The invention discloses an all-fiber LD-pumped multi-mode optical fiber cascaded Raman random laser, comprising: an LD pumping laser source group, the output end of the LD pumping laser source group is connected to a multi-mode optical fiber combiner, and multiple The output end of the mode fiber combiner is connected to a mode field adapter, the output end of the mode field adapter is connected to a fiber grating string, the output end of the fiber grating string is connected to a multimode fiber, and the input and output fibers of the multimode fiber combiner have the same core diameter and The fiber type at the input end is the same as the output fiber type of the LD pump laser source, the fiber type at the input end of the mode field adapter is the same as that at the output end of the multimode fiber combiner, and the fiber type at the output end of the mode field adapter and the fiber grating string are the same as those of the multimode fiber same type. Using a specific matching multimode fiber combiner and a matching mode field adapter, the matching fiber grating series can be cascaded to obtain a cascaded Raman random laser with high beam quality and high power.

Description

technical field

[0001] The invention belongs to the technical field of fiber lasers, in particular to an all-fiber LD-pumped multimode fiber cascaded Raman random laser. Background technique

[0002] High-power fiber random lasers have excellent performance in terms of beam quality, output power, and efficiency, and can be widely used in industrial applications and can be used as powerful pump sources for mid-infrared laser generation. Most high-power fiber random lasers usually couple multiple LDs into a double-clad active fiber doped with rare earth elements Yb, Er, etc., through a multimode fiber combiner, so that the corresponding emission bands, for Yb-approx. 1.05 μm and about 1.55 μm for erbium-doped fiber provide amplification. However, Raman lasers based on pumping to introduce Raman gain in passive fibers have small quantum defects, fast gain response, low background spontaneous emission, and no photodarkening effect compared with Er or Yb-doped fiber lasers. adv...

Examples

Embodiment 1

[0039] An all-fiber LD-pumped multimode fiber cascaded Raman random laser provided by a preferred embodiment of the present invention uses a multimode fiber combiner whose fiber core matches the LD pump laser source to match the mode field adapter effectively Increase the coupling efficiency of the pump laser into the graded-index multimode fiber, provide sufficient pump light power, realize the cascading of the fiber grating series, and the Raman gain plays a role in purifying the beam quality, so as to obtain high beam quality and high power level Combined Raman random laser. Including the LD pumping laser source group with the core diameter / cladding diameter of the output fiber being 105 / 125 μm and NA being 0.15, the output end of the LD pumping laser source group is connected with a multimode fiber combiner with the same core diameter of the input and output fibers , the output end of the multimode fiber combiner is connected with a mode field adapter, the output end of th...

Embodiment 2

[0041] Based on the first embodiment, the graded-index multimode optical fiber is 4.3 km long.

[0042] figure 2 It is the simulation diagram of the power input and output curves when the graded index multimode fiber is 2.1km and 4.3km respectively and the fiber grating string N=2 in the present invention, the abscissa corresponds to the pump power value, and the ordinate corresponds to the output power value at the end of the fiber. When the length of the graded-index multimode fiber 5 is 4.5 km, the output power is relatively small due to the large fiber loss, but because sufficient fiber length provides sufficient Rayleigh feedback, the first and second order thresholds are low; when When the length of the graded-index multimode fiber 5 is 2.1 km, the threshold value is higher than that of the 2.5 km scheme because the Rayleigh feedback provided is smaller than that of 4.5 km, but because the fiber loss is small, the output power and the slope Higher efficiency.

technical field

[0001] The invention belongs to the technical field of fiber lasers, in particular to an all-fiber LD-pumped multimode fiber cascaded Raman random laser. Background technique

[0002] High-power fiber random lasers have excellent performance in terms of beam quality, output power, and efficiency, and can be widely used in industrial applications and can be used as powerful pump sources for mid-infrared laser generation. Most high-power fiber random lasers usually couple multiple LDs into a double-clad active fiber doped with rare earth elements Yb, Er, etc., through a multimode fiber combiner, so that the corresponding emission bands, for Yb-approx. 1.05 μm and about 1.55 μm for erbium-doped fiber provide amplification. However, Raman lasers based on pumping to introduce Raman gain in passive fibers have small quantum defects, fast gain response, low background spontaneous emission, and no photodarkening effect compared with Er or Yb-doped fiber lasers. adv...

Examples

Embodiment 1

[0039] An all-fiber LD-pumped multimode fiber cascaded Raman random laser provided by a preferred embodiment of the present invention uses a multimode fiber combiner whose fiber core matches the LD pump laser source to match the mode field adapter effectively Increase the coupling efficiency of the pump laser into the graded-index multimode fiber, provide sufficient pump light power, realize the cascading of the fiber grating series, and the Raman gain plays a role in purifying the beam quality, so as to obtain high beam quality and high power level Combined Raman random laser. Including the LD pumping laser source group with the core diameter / cladding diameter of the output fiber being 105 / 125 μm and NA being 0.15, the output end of the LD pumping laser source group is connected with a multimode fiber combiner with the same core diameter of the input and output fibers , the output end of the multimode fiber combiner is connected with a mode field adapter, the output end of th...

Embodiment 2

[0041] Based on the first embodiment, the graded-index multimode optical fiber is 4.3 km long.

[0042] figure 2 It is the simulation diagram of the power input and output curves when the graded index multimode fiber is 2.1km and 4.3km respectively and the fiber grating string N=2 in the present invention, the abscissa corresponds to the pump power value, and the ordinate corresponds to the output power value at the end of the fiber. When the length of the graded-index multimode fiber 5 is 4.5 km, the output power is relatively small due to the large fiber loss, but because sufficient fiber length provides sufficient Rayleigh feedback, the first and second order thresholds are low; when When the length of the graded-index multimode fiber 5 is 2.1 km, the threshold value is higher than that of the 2.5 km scheme because the Rayleigh feedback provided is smaller than that of 4.5 km, but because the fiber loss is small, the output power and the slope Higher efficiency.

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