Research On High Energy Ytterbium Doped All-fiber Femtosecond Laser Three-dimensional Direct Writing System

With the further research of micro/nano photonics,micro/nano photonic devices are developing towards the direction of new materials,multi-function,high precision and three-dimensional structure,which puts forward higher requirements for the fabrication technology of devices,and various new fabrication technologies arise at the right moment.Femtosecond laser 3D direct writing system has unique advantages.As the working light source and the core component of laser direct writing system,femtosecond laser can be used in a wider range of applications and has a finer 3D direct writing capability.At the same time,due to its advantages in beam quality,integration and cost,all-fiber femtosecond laser is gradually replacing Ti:Sapphire laser as the laser source of femtosecond laser direct writing system.In this paper,the main research objective is to develop a high energy ytterbium-doped all-fiber femtosecond laser,and the systematic research has been carried out including ultra-fast ytterbium-doped fiber oscillator,high energy chirped pulse amplification system,engineering prototype of femtosecond laser and design and construction of femtosecond laser three-dimensional direct writing system.The main contribution and innovaton of this dissertation are presented as follows:1.Research on all-fiber ytterbium-doped ultrafast laser oscillatorIn the dissipative soliton mode-locked region,a semiconductor saturable absorber mirror dissipative soliton passively mode-locked fiber laser based on ring cavity structure is constructed.The central wavelength of output laser is 1030 nm,the average power is 3 m W,the pulse repulse frequency is 34.2 MHz,and the pulse width after unchirped is 1.117 ps.A chirped fiber bragg grating dispersion-managed soliton passively mode-locked fiber laser based on linear cavity structure was constructed in the dispersion-managed soliton mode-locked region.The central wavelength of the output laser was 1033 nm,the spectral width of 3 d B was 21 nm,the average power was 5.5 m W,the pulse repetition frequency was 48 MHz,and the pulse width was 2.858ps.2.Research on High pulse energy femtosecond ytterbium-doped chirp pulse amplification systemFirstly,the main parameters of pulse expander and pulse compressor commonly used in chirped pulse amplification system are compared and analyzed.A ytterbium-doped all-fiber femtosecond chirped pulse amplification system with high monopulse energy was constructed using a dispersion-managed soliton mode-locked fiber laser as the seed source,a long-distance polarization-maintaining single-mode fiber and a fiber mirror constitute a dual-path pulse stretcher,a two-stage core preamplifier,a primary cladding amplifier and a transmission diffraction grating pairs as the pulse compressor.An ultrashort-pulsed laser with a central wavelength of 1030 nm,an average power of10 W,a repetition frequency of 500 k Hz,a pulse width of 634 fs,a single pulse energy of 20?J,and a peak power of 31.54 MW was obtained.The beam quality M~2factors in horizontal and vertical directions are respectively M_x~2=1.44 and M_y~2=1.65.3.Research on three-dimensional femtosecond laser direct writing systemIn order to further improve the integration of high-energy femtosecond chirped pulse amplification system,the hardware circuit of laser pump source driver board and serial port panel control board was independently designed,and corresponding control programs were written for the microcontroller and intelligent serial port panel by using VS-Code and USART-HMI software.Solid Works software was used to design the integrated mechanical dimensions of the laser prototype,and the power stability of the engineering prototype was tested for 90 minutes.Finally,a complete femtosecond laser three-dimension direct writing system was successfully developed after the design and construction of the high precision beam regulation system,microscopic imaging system and three-dimension writing platform.Single point writing and line etching on the optical fiber surface have been carried out by using the direct writing system.