Research On Intensity And Phase Tunable Comb Filter

Optical arbitrary waveform generator (OAWG), which is a versatile ultrafast laser, cangenerate output signal pulses in arbitrary waveform. OAWG has advantages that the past light laserdoes not have. For instance, it breaks the electronic bottleneck for speed and utilizes thelow-frequency pulse source to generate high-frequency of arbitrary light pulse. Hence, OAWG hasbeen widely applied in the field of ultra-high speed optical communication, microwave photonics,and high quality light producing. Structure of OAWG is mainly composed of the stable comb lightsource and the pulse shaper. The principle of pulse shaping is the most important part of OAWGtechnology. The pulse shaper which can adjust the amplitude and phase of each spectral lineindependently, as the key of OAWG pulse shaping has been widespread concerned. In this thesis,theoretical research for all-fiber intensity and phase controllable comb filter based on Fouriertransform is proposed, and ultimately realize of OAWG pulse shaping. The main achievements andconclusions are listed as follows:(1) The research signification of intensity and phase tunable comb filter is analyzed. Theresearch background of the line-by-line shaping technique in OAWG is summarized.(2) A novel shame for all-fiber intensity and phase controllable comb filter is presented. Thecouple mode theory models of intensity modulator, phase modulator and comb filter areestablished based on mode coupling theory in single mode filer. In this model, the impactof birefringence effected on the structure parameters of intensity and phase modulators areconsidered. Eventually, blameless theoretical model about intensity and phase controllablecomb filter is established combined with the transfer matrix theory.(3) By using the software of Matlab (2011a), the performance on the magnitude and phasetunable comb filer is studied. The impacts of structure parameters in fiber micro-bendintensity modulator, fiber PZT phase modulator and superstructure fiber Bragg grating(SSFBG) on the output spectrum are simulated and studied, and ultimately optimize itsstructural parameters to improve the output spectral resolution, and the modulatedprecision of intensity and phase modulator.(4) According to the principles of the Fourier transform of plastic and the all-fiber intensityand phase controllable comb filter, a new optical arbitrary waveform pulse shaping systemis designed. In this new scheme, periodic Gaussian pulse, periodic triangular signal pulse and arbitrary waveform signal pulse are generated successfully, and also the similaritybetween the real output waveform and ideal waveform are studied.