Directly-pumping self-stimulated Raman scattering human eye safe waveband laser

Abstract

The invention discloses a directly-pumping self-stimulated Raman scattering human eye safe waveband laser. The laser comprises a laser pumping source, a laser energy transmission fiber, a plano-convex lens collimator, a plano-convex focus lens, a cavity reflector, a laser gain medium crystal, a laser output mirror and a laser collimating lens, wherein pumping light output by the laser pumping source is transmitted to the plano-convex lens collimator through the laser energy transmission fiber; after being collimated, the pumping light is focused on the end face of the laser gain medium crystal through the plano-convex focus lens; the laser gain medium crystal absorbs the pumping light and generates stimulated radiation with a waveband of 1.3 microns; and when the radiation with the waveband of 1.3 microns surpasses a self-stimulated Raman scattering threshold value of the laser gain medium crystal, generated human eye safe waveband laser with the waveband of 1.5 microns is collimated and output by the output mirror. The laser has the advantages of enhancing self-stimulated Raman scattering conversion rate in the waveband of Nd3+1.3 microns, eliminating thermal relaxation process of electronics from a pumping energy grade to a laser energy grade in a conventional pumping mode, enhancing quantum efficiency and reducing heat.

Description

technical field [0001] The invention relates to a laser, in particular to a directly pumped self-stimulated Raman scattering laser in a human eye-safe band. Background technique [0002] The 1.5-micron eye-safe band laser has important applications in laser ranging, laser space communication, medical treatment and other fields. At present, there are mainly optical parametric oscillation (OPO), Er glass lasers, semiconductor diode lasers, etc. to realize the 1.5 micron human eye-safe laser band. However, OPO has a complex structure, high cost, and poor stability, which is not conducive to miniaturization and commercialization. Er glass It can emit a laser with a wavelength of 1.54 microns, but because Er glass has a three-level structure, it has little absorption of pump light, low efficiency, and the thermal conductivity of Er glass is very low, so there are few practical applications. Semiconductor laser diodes can also generate laser light in the 1.5 micron band, but thei...

AI Technical Summary

Problems solved by technology

At present, there are mainly optical parametric oscillation (OPO), Er glass lasers, semiconductor diode lasers, etc. to realize the 1.5 micron human eye-safe laser band. However, OPO has a complex structure, high cost, and poor stability, which is not conducive to miniaturization and commercialization. Er glass It can emit a laser with a wavelength of 1.54 microns, but because Er glass has a three-level structure, it has little absorption of pump light, low efficiency, and the thermal conductivity of Er glass is very low, so there are few practical applications

Semiconductor laser diodes can also generate laser light in the 1.5 micron band, but their beam quality is poor, which limits their applications

[0003] In recent years, using Nd:YVO 4 , Nd:GdVO 4 Eye-safe lasers in the 1.5-micron band produced by the self-stimulated Raman scattering of the 1.3-micron band of the crystal have gradually attracted people's attention. This laser has a simple structure, low cost, and is easy to implement, but the efficiency of this method is not very high. This is because the quantum efficiency of 1.3 micron pumped by 808nm is very low, and the heat generation is large, which largely suppresses the generation of stimulated Raman scattering in the 1.3 micron band, and the efficiency is not very high. The highest efficiency obtained so far is 2009 The article "Compactefficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO4crystal as a self-Raman medium" published on OPTICS EXPRESS (Optical Express) Composite Nd:YVO4 crystal self-Raman 1525nm eye-safe band laser), this article uses Nd:YVO4 4 The crystal uses a fiber-coupled output 808nm fiber-coupled output array as the pump source, and adopts the pulse work method. When the pump power is 17.2W, the laser output in the 1525nm band of human eyes is obtained at 2.3W, and the light-to-light conversion rate is 13%, although this method uses coincident crystals to reduce the thermal effect of laser crystals and improve the efficiency of stimulated Raman scattering, this method does not fundamentally reduce the generation of heat

[0004] Patent CN101276984 proposes a laser gain medium using microchip Nd3+ ions, V:YAG passively Q-switched self-stimulated Raman scattering to generate a human eye-safe band, because the method uses a microchip structure, the efficiency is low

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