Design And Research Of Single Frequency Laser Based On Yb:YAG Crystal Derived Fiber

With the progress of laser technology,single frequency fiber laser is widely used in the sensing field.Among them,1 ?m band laser has broad application prospects in laser guidance,space detection and other high-tech fields due to its excellent far-field beam characteristics,transmission characteristics and low space background noise.In this paper,the optical path of DBR single frequency fiber laser based on the Yb:YAG crystal derived fiber is built.Aiming at the problem of poor output stability,the constant current circuit,temperature control system and mechanical shell are designed.After the assembly,the DBR single frequency fiber laser prototype is researched again.The details are as follows.Firstly,Yb:YAG crystal derived fiber is obtained by "secondary drawing" method with drawing tower,the seed optical path of DBR single frequency fiber laser based on special fiber is designed.The bare machine of DBR fiber laser is built by a simple fixed way,the preliminary performance test of the bare laser is carried out.The test results show that the OSNR is about 59dB,the center wavelength is 1064.43nm,and the wavelength shift is 5pm in 3 hours;when the seed pump power is 79mW,the output power is 13.3mW;when the pump power of MOPA is 180mW,the output power is 102.2mW,and the power fluctuation is 0.26%in 3 hours;because of the absence of whole packaging of temperature control module,it is tough to obtain single-mode in normal environment.After turning off the air conditioning fan and other instruments which have a great impact on the environmental stability,the single-mode output is realized at 20?,and the linewidth is 4kHz measured.The output power and wavelength of the bare laser fluctuate obviously,at the same time,it is necessary to keep the ambient temperature fluctuation and environmental vibration in a low state when realizing the single mode.The above problems are mainly caused by the instability of LD pump output,the poor temperature control effect of the temperature control module of the resonator and the weak anti-interference ability of the laser optical path.Then,aiming at the problems in the bare metal experiment of the laser,the LD pump constant current drive circuit,TEC temperature control circuit,the resonant cavity temperature control box and mechanical shell with better thermal insulation and vibration isolation effect are designed.The resonant cavity is fixed with soft glue to reduce the impact of external shock.Lab VIEW PC control program is designed to reduce the operation difficulty of low DBR single frequency fiber laser.After the above improvements,a laser prototype is obtained by assembling the optical path,circuit board and mechanical shell.Finally,the laser prototype is tested with the same instrument at the same temperature.The test results show that the OSNR is about 63dB,the center wavelength is 1064.46nm,the wavelength shift is 2pm in 48 hours;when the pump power of amplified light is 180mW,the output power is 105.6mW,and the power fluctuation is 0.096%in 48 hours;under normal experimental conditions,stable single-mode output whose linewidth is 3kHz is achieved when the cavity temperature is set at 20?.When the frequency exceeds 3.2 MHz,RIN is stable at-110dB/Hz;about frequency noise,white noise is 10 ? Hz,1/f noise bottoms out at 50kHz.The test results show that Yb:YAG crystal derived fiber is a kind of fiber with good application prospects,and the output stability of DBR single frequency fiber laser based on Yb:YAG crystal derived fiber is obviously improved after design.