Study On Multi-wavelength Fiber Lasers With Narrow Line Width And Their Applications

Multi-wavelength fiber laser has been widely studied in recent years due to its narrow line width,a large number of laser lines,low cost,compatibility with fiber system and wide tunable range.According to Stimulated Brillouin scattering effect in optical fiber,multi-wavelength Brillouin-Raman fiber laser(MBRFL),multi-wavelength Brillouin fiber laser(MBFL),beat frequency microwave signals based on MBFL and high-sensitivity temperature sensor based on MBFL have been studied from theory to experiment in this thesis.The main research results are summarized as follows:1.A MBRFL in a linear cavity has been designed.The MBRFL is a hybrid gain multiwavelength fiber laser which combines two nonlinear effects of stimulated Brillouin scattering effect and stimulated Raman scattering effect in fiber.The dispersion compensated fiber(DCF)acts as a Brillouin gain medium and a Raman gain medium,and the DCF also provides random distributed Rayleigh feedback.245 Brillouin Stokes lines with 0.072 nm channel-spacing are generated across the wavelength range of 18.6 nm from 1544.98 nm to 1563.58 nm.Finally,we investigate the effect of Rayleigh scattering on the spectrum shaping.2.MBFLs with three different wavelength spacing have been designed.Based on the different wavelength spacing MBFLs,10.5 GHz?21.48 GHz and 31.77 GHz beat frequency microwave signals are generated by utilizing optical heterodyne technique respectively.The beat frequency microwave signals have good stability at room temperature.In the first MBFL,9 Brillouin Stokes lines including Brillouin pump with 0.084 nm channel-spacing are generated across the wavelength range from 1544.98 nm to 1563.58 nm.In the second MBFL,odd-order Brillouin stokes lines and even-order Brillouin stokes lines are separated through structural design.7 even-order Brillouin Stokes lines including Brillouin pump and 16 odd-order Brillouin Stokes lines with wavelength spacing of 0.175 nm are obtained.The third MBFL can generate 9 Brillouin Stokes lines with wavelength spacing of 0.259 nm.3.Based on the double frequency spacing MBFL,a high-sensitivity fiber temperature sensor is designed.High-order Brillouin stokes pairs generated by two double frequency spacing MBFLs are used to beat frequency to obtain microwave signals.Then we demodulate the microwave signals and get the temperature information to realize the high-sensitivity fiber temperature sensing.The sensing sensitivity is up to 13.083 MHz/?.