Precise Control Of Ultrashort Pulse Laser In The Time And Frequency Domain

Ultrashot pulse laser technology has provided us measurement tools of high time resolution and high frequency accuracy, with which we can improve our ability to explore the law of nature. Precise control of the ulrashort pulses in the time and frequency domain has become a crucial key to research the frontier science and leading technology. In this dissertation, theoretical and experimental investigation was given on this topic. In the time domain of ultrashort pulse generation, the theory and configuration of the mode-locked laser were detailed discussed, and then femtosecond fiber lasers were built to do the research on precise control of ulashort pulse. In the time domain of pulsed laser synchronization, harmonic mode-locked laser, multi-colour laser and square nanosecond laser were synchronized to a master ultrashort pulse laser. In addition, an application of the synchronized ulrashort pulses has been illustrated in the single photon upconversion detection system. In the precise control of frequency domain, a carrier-envelop offset frequency stabilized ultrashort pulse laser system with an average power up to 50 W has been developed, which lays a foundation for the generation of ultraviolet and extreme ultraviolet frequency combs.The detailed works in this dissertation include:1. Ultrashort pulse laser generation is the basis for preside control in the time and frequency domain. Based on the theoretical and experimental development of ultrashort pulse laser, femtosecond mode-locked fiber lasers have been accomplished.1) Mode-locked erbium-doped fiber laser has been realized with the nonlinear polarization rotation effect in fiber. When the net dispersion of the cavity is negative, the pulses are running like solitons. The peak power of the pulse is constrained and the pulse duration is relatively long. So, dispersion management is introduced and then the laser is mode-locked in the stretched-pulse way. With this technology, pulse duration of 92 fs has been obtained in the mode-locked erbium doped fiber laser.2) Wave-breaking free ytterbium doped fiber laser was realized by insertion of a piece of erbium-doped fiber in the cavity. The inserted erbium doped fiber acted as an additional saturable absorber to suppress intra-cavity wave-breaking. The pulse duration of the wave-breaking free mode-locked ytterbium doped fiber laser was measured to be 41 fs.2. When different wavelength lasers propagate in the fiber, the nonlinear refractive index of one laser will be changed by another through cross phase modulation. The change of nonlinear refractive index will lead to nonlinear polarization rotation. With this effect, the synchronization among pulsed lasers in the time domain was realized.1) With master-slave cavity configuration, harmonic mode-locked Er-fiber laser was synchronized to a passively mode-locked Yb:GSO laser with a mismatch length of 14 mm based on cross phase modulation. At large cavity mismatch length, the pulse duration was stretched which has a potential application in pulse shaping and optical parametric chirped pulse amplification.2) Synchronization was obtained among 3-color ultrashort pusles at 800 nm, 1030 nm,1550 nm based on fractional spectrum amplification and cross phase modulation. The timming jitters between 800 nm,1030 nm and 1030 nm,1550 nm were 0.55 fs and 8.3 fs respectively.3) Square 5.5 ns mode-locked laser was generated in the long cavity with peak power clapping effect. Then the square ns pulse was synchronized to an ultrashort pulse laser with an all optical way. The timming jitter of the two lasers was 4.3 ps with a maximum cavity mismatch length of 2.6 mm.4) High speed single photon frequency upconversion was achieved by synchronized mode-locked Er-fiber laser and Yb-fiber laser, the maximum conversion efficiency of the infrared single photons was 31.2%。3. In the precise control in frequency domain, high repetition and high power carrier-envelop offset frequency stabilized ultrashort pulse laser has been realized. Based on chirped pulse double clad fiber amplifier technology, an average output power of 50 W was obtained. The carrier-envelope offset frequency was detected by a cross-reference interferometer and locked by the electronic feed-back loops. The stabilized carrier-envelop offset frequency has an out of loop linewidth of 2.27 mHz. The phase noise between the carrier and envelop is 0.72 rad with the according timming jitter of 300 as. The average power of the carrier-envelop phase stabilized ulstrashort pulses in our experiment is five times larger than that has ever been reported in the world. This work opens a way for generating ultraviolet and extreme ultraviolet frequency combs in the future.