Research On Passively Mode-locked Fiber Laser For High-speed All-optical Sampling

As an effective method for high speed optical signal characterization, optical sampling is a key technique for high-speed optical oscilloscope, all-optical analog-to-digital conversion, and high-speed optical signal processing. In order to realize high precision measurement, we genarally need a stable and reliable optical sampling pulse source, which has several chacteristics including narrow pulse width, low timing-jitter, high repetition rate and wide wavelength-tuning range. Moreover, according to the operation principle of linear optical sampling, there must exit spectral overlap between the signal under test and the sampling source. In addition, in order to reduce the sampling error, the sampling source must have a wide and flat rectangular optical spectrum.In this dissertation, which supported by the 2013 national major scientific instruments and equipment development – broadband high-speed optoectronic signal analyzer, we investigate the passively mode-locked fiber laser as all-optical sampling source. For SESAM-based passively mode-locked fiber laser, we obtain soliton pulse output at the anomalous dispersion regime and dissipative soliton pulse output at the normal dispersion regime after dispersion optimization. The repetition rate of the dissipative soliton pulse is 20.3 MHz, while its pulse width is 19.8ps. Moreover, a flat rectangular optical spectrum with 3dB bandwidth of 8.1nm is obtained, which can be used for future all-optical sampling equipment. Additionally, we obtain multi-wavelength mode-locked pulse output and wavelength-tunable mode-locked pulse output.The thesis can be divided into four parts. Firstly, the optical sampling technique and the mode-locked fiber laser is briefly introduced. The development of the all-optical sampling technique and optical sampling source is reviewed. The second chapter mainly introduces the operation principle, the implementation of different mode-locked fiber laser and several pulse characteristics at different dispersion regime. In the third chapter, we achieve soliton pulse output based on SESAM mode-locker at the anomalous dispersion regime. The sideband asymmetric phenomena of the soliton pulse is invesitigated. In the fourth chapter, we obtain the dissipative soliton pulse output with a repetition rate of 20.8 MHz, pulse duration of 19.8ps and 3dB bandwidth of 8.1nm. What's more, we also demonstrate multi-wavelength mode-locked fiber laser and wavelength-tunable mode-locked fiber laser.