Research On 1.7?m Band Fiber Laser Based On Nonlinear Effect

1.7?m band fiber laser has great application prospects in the fields of bio-imaging,laser medical treatment,special material processing,micro-measurement of organic matter,mid-infrared laser generation and so on,and has become a research hotspot at home and abroad.In this paper,a 1.7?m band fiber laser is designed and experimentally studied by means of the nonlinear effect of fiber.The main contents can be divided into the following three parts:?1?Research of 1.7?m band gain spectrumFirstly,the related theory of generating 1.7?m band gain spectrum is studied based on ion-doped fiber and nonlinear effect of fiber.The energy level structure and spectral characteristics of Bi⁺,Tm³⁺,ions of Tm,Ho co-doped fiber and Tm,Tb co-doped fiber are analyzed,and the mechanism of generating gain spectra based on different pumping sources is also analyzed.Secondly,according to theoretical analysis,we built an experimental system of generating 1.7?m band gain spectrum is established based on nonlinear effect.A spectrally sliced amplified spontaneous emission?SS-ASE?light source is used as the pump source.After shaping and optimizing the spectrum,a spectrum with 20dB range of1570.9-1710.5nm,peak wavelength tunable range of 20nm and peak power of-35dBm was obtained.In addition,a picosecond pulse pump source based on cascaded modulator is designed.When the center wavelength of pump is 1565 nm,the amplified optical power reaches the maximum,and an optimal gain spectrum with 20dB range of 1528.6-1910.4nm is obtained.?2?Experimental research of 1.7?m continue-wave laserThe performance of various filters is analyzed theoretically.Then,a 1.7?m band tunable narrow-linewidth Raman fiber laser based on the gain spectrum generated by the SS-ASE pump.The center wavelength of the single laser output can be tuned from1652.1nm to 1680.1nm,and the effective linewidth is 0.0232nm.In addition,the stable multi-wavelength laser operation of up to four wavelengths can be obtained by increasing the pump power and adjusting the polarization controller?PC?.?3?Experimental research of 1.7?m picosecond-pulse laserA picosecond-pulsed source based on the gain spectrum generated by the cascaded modulator pump and multiple filter structures.The wavelength of the picosecond-pulsed output can be tuned from 1660.1nm to 1703.7nm,and the pulse duration is estimated as 151ps.A 1.7?m band single/dual-pulse switched picosecond-pulsed light source based on single modulator is designed and implemented.The signal/dual-pulse train can be obtained and switched by adjusting the direct current?DC?bias of intensity modulator.The center wavelength of the light source is 1726.9nm,and 20dB spectrum range is from1570.9-1710.5nm.The pulse duration of dual-pulse train is between 60ps and 180ps,when the repetition rate of the generated pulse train is from 170MHz to 2GHz.The continue-wave laser can effectively reduce the quantum defect of mid-infrared laser,and the picosecond pulse laser can improve the imaging depth as a source of optical tomography.The research content is of great significance for the research and application of1.7?m band fiber laser.