All-polarization Ytterbium-doped Passive Mode-locked Fiber Laser

Mode-locked laser is an important research direction in the laser field,especially all polarization-maintaining passive mode-locked ytterbium-doped fiber lasers,which have the advantages of easy integration,small size,and good stability.Ytterbium-doped fiber lasers and amplifiers have a wide range of scientific value and industrial application value.Due to the high optical-to-optical conversion efficiency and good thermal-optical characteristics of ytterbium-doped fiber,they can provide ultra-short pulses with high energy and high peak power,becoming ideal light source for micro-nano processing,Biological imaging and large laser devices.The main research results of this paper are as follows:1.Based on the principle of nonlinear amplified loop mirror(NALM),an all-positive dispersion ytterbium-doped fiber mode-locked laser is introduced.The oscillator adopts a figure-"9" type all polarization maintaining fiber structure,and a transmissive Faraday phase retarder is inserted into the cavity to complete the accumulation and matching of the phase shift,reduce the mode locking threshold,and realize the self-starting function of the mode locking laser.In the case of pump power of 80 mW,the ytterbium-doped fiber mode-locked laser can achieve a stable output with an average power of 7.8 mW,the repetition rate of the output laser pulse is 9.9 MHz,and the center wavelength is 1064 nm.As measured by a time-frequency domain instrument,the pulse width of its output pulse is about 18 ps,and the spectral width is 0.18 nm.2.Based on Master Oscillator Power-Amplifier(MOPA)technology and circuit-driven electro-optic devices to reduce the repetition rate of optical pulses,and to achieve frequency doubling by using periodic polarized lithium niobate crystals(PPLN)It is successful to conver the seed light which the average power is 7.8 mW,repetition rate is 10 MHz center wavelength is 1064 nm to the dual-wavelength pulse laser output which the repetition rate is 10 kHz,the center wavelength are 1064 nm,and 532 nm.And the single pulse energy at 532 nm is 0.82 nJ.3.Based on SESAM mode-locking technology,combined with CFBG,using ytterbium-doped fiber as the gain fiber,developed a linear cavity all polarization-maintaining fiber-structured ytterbium-doped fiber laser,achieving a repetition rate of 20.23 MHz,an average power of 14.7mW,and a center wavelength of 1064 nm,picosecond pulse laser output with a spectral width of 1.65 nm.