Research On Generation And Amplification Of Near/Mid-Infrared Pulsed Laser At Different Wavelength

The pulsed lasers are widely used in biomedicine,industrial processing,space communication and advanced scientific research,based on the characteristic of high peak power.Among different types of pulsed lasers,the all-solid-state pulsed laser and fiber pulsed laser are proved to be important in investigating the characteristics of the pulsed lasers.The corresponding output power,pulse duration and pulse energy are very important technical parameters for pulsed laser.Recently,the output power of pulsed laser oscillator is limited,which can not directly fulfill the requirements of the related applications.Therefore,it is necessary to design the laser amplifier to scale up the average power and pulse energy of the pulsed lasers.In the optical fiber amplifiers,the influences of the nonlinear effects such as the stimulated Raman scattering and the stimulated Brillouin scattering become significant,when the peak power of the optical pulses exceeds the corresponding power threshold.The further improvement of the average power is limited.Therefore,it is of great scientific significance and practical value to carefully investigate the pulsed laser generation and the corresponding amplification process.This dissertation mainly describes the theoretical and experimental results of the investigations in generating and amplifying the near/mid-infrared pulsed laser.The main contents of this dissertation are as follows:1.The Nickel-cobalt layered double hydroxide saturable absorber and the Nickel-vanadium layered double hydroxide saturable absorber were fabricated based on the liquid-phase exfoliation method.And the structure,component and optical absorption properties of the Ni-based LDHs were investigated.The saturable absorption properties in the 3-μm wavelength region were further characterized with the I-scan method.The Q-switched Er:YAP lasers were realized by applying the Ni-based LDH SAs as the optical modulation devices.The optical pulses with the shortest pulse duration of 141 ns were realized with the corresponding repetition rate of 295 kHz.The perfect nonlinear optical modulation characteristics of the Ni-based LDHs in the 3-μm pulsed laser generation was proved,based on the experimental results.2.Based on the optical pulse modulation,the high-peak-power,single-frequency,1.55μm fiber laser amplification with the master oscillator power amplifier configuration was demonstrated.The 1548-nm,single-frequency,continuous-wave laser was utilized as the seed laser,which was modulated into the 10-kHz single-frequency pulsed laser by two acousto-optic modulators.And different types of the temporal modulated pulsed were employed as the signal pulses,in order to investigate the pulse-profile distortion during the amplification process.Based on the aforementioned experimental results,a customized pulse profile was proposed.The stimulated Brillouin scattering effect was inhibited,owing to the customized pulse profile.Finally,a 10-kHz,353-μJ,574-ns,1548-nm single-frequency fiber laser system was achieved.3.Based on the principle of nonlinear amplifying loop mirror,an all-positive dispersion mode-locked fiber oscillator was fabricated.The mode-locking state can be achieved under the pump power of 130 mW.The central wavelength and repetition rate of the mode-locked laser were 1030 nm and 32.77 MHz,respectively.The single-mode fiber nonlinear amplification system was fabricated to investigate the four wave mixing effect in the photonic-crystal fiber.Besides,the stretched-pulse mode-locked fiber oscillator was fabricated by applying a nonlinear amplifier loop mirror.Based on the optimization of the intra-cavity loss and net cavity dispersion,a 1090-nm mode-locking state was achieved.The measured repetition rate of the mode-locked pulse train was 39.7 MHz.The 1090-nm fiber nonlinear amplification system was fabricated by applying pre-chirp managed amplification.The 10-nJ,55.5-fs amplified signal pulses can be delivered by the system.