Experimental Studies On A 4.77 GHz Mode-filter Of An Erbium-doped Fiber Comb

Optical frequency comb which works as a repetition-rate and carrier-envelop offset frequency controlled mode-locked laser,has been widely used in optical frequency transfer and comparison? precision spectroscopy?ultra-stable microwave source and so on.The special optical frequency comb applied in the astronomical spectroscopy is significant for the development of astronomy.It can work for astronomical spectrometer to raise measurement accuracy by two orders of magnitude,1 cm / s.This kind of optical frequency comb,which has a ultra-high repetition-rate(> 10 GHz),is called astronomical comb.The repetition-rate of the optical frequency comb is generally between 100 MHz and 1 GHz.While the high resolution astronomical spectrometer has a limited resolution capability and can identify the minimum optical comb interval of 10-30 GHz.Therefore,the primary prob lem of applying the optical frequency comb to the astronomical spectroscopy is to increase the repetition-rate of the optical frequency comb.In order to solve the problem,this thesis has carried out the experimental study of high repetition-rate femtosecond pulse laser taking Fabry-Perot(F-P)cavity mode-filtered method.In this paper,a high repetition-rate femtosecond pulse laser source based on a home-made femtosecond erbium-doped fiber mode-locked laser?a F-P mode-filtered cavity and Tilt-Lock electric circuits is realized,by locking the Fabry-Perot cavity resonant position to the modes with Free Spectral Range(FSR)of 4.77 GHz.The transmission power is about 0.246 mW and the repetition-rate of the mode-filtered comb is 23 times higher than the home-made mode-locked laser.The main experimental contents and results of this thesis include the following aspects:1.Based on the Nonlinear Polarization Rotation(NPR)Mode-Locking,a femtosecond erbium-doped fiber mode-locked laser is achieved.The repetition-rate of the mode-locked laser is about 207 MHz.The pulse width is 52 fs.The spectral wavelength covers from 1425 nm to 1700 nm and the center wavelength is 1565 nm.The home-made femtosecond erbium-doped fiber mode-locked laser which has the feathers of high-stability and high practicality is long-term stable mode-locked(more than three months in succession).The home-made erbium-doped femtosecond fiber laser works as an input laser source of the mode-filtered system.2.Based on the F-P cavity mode-filtered method,a F-P mode-filtered system is realized.The transmission signal and the error signal(peak-to-peak value 30 mV)of the mode-filtered system are detected by DC detector and four quadrant detector respectively.Using the Tilt-Lock frequency stabilization technique,a high repetition-rate femtosecond pulse laser source is realized by locking the Fabr y-Perot cavity resonant position to the modes with FSR of 4.77 GHz.The Tilt-Lock technique has the same reaction speed compared to the conventional Pound-Drever-Hall(PDH)technique.At the same time,the Tilt-lock technique employed in this experiment will not add the modulation noise to the system.The results show that the F-P cavity mode-filtered method and Tilt-Lock frequency stabilization technique can realize the generation of the high repetition-rate pulse laser and can be applied to the following research of the astronomical comb.