High power narrow linewidth fiber laser based on superfluorescent white noise modulation

Abstract

High power narrow linewidth fiber lasers have important applications in the fields of national defense, military and industrial intelligent manufacturing. At present, the power enhancement of narrow linewidth lasers is limited by the nonlinear and thermal effects of fiber, among which the stimulated Brillouin scattering (SBS) effect is highly destructive due to its low threshold. The SBS effect is easily produced using a single frequency laser as the seed of a high power narrow linewidth laser directly. The Brillouin scattering threshold can be effectively increased by broadening the spectrum line at a single frequency. A spectral broadening technique for single frequency lasers based on superfluorescent white noise modulation was proposed. The broadband characteristics of the amplified spontaneous emission light source to generate noise voltage on the photodetector was employed, and the lithium niobate electro-optical modulator was driven to perform broadband phase modulation in a single frequency laser. The phase modulation broadening of the single frequency laser was carried out using superfluorescent white noise. Different linewidth broadening effects of single frequency lasers were realized by changing the amplitude of the white noise. An experimental platform of the four-stage main oscillation power amplification structure was built, and a high power narrow linewidth laser with output power of 2 kW and spectral linewidth of 0.15 nm (10 dB) was realized, which effectively inhibited the SBS effect of the laser.