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In this thesis, we demonstrate a new stabllization method based on an optoelectronic harmonic mixer (OEHM) biased by picosecond electrical pulse in a phase-locked loop to reduce and measure the timing jitter of the passively mode-locked Ti: sapphire laer. We stabilize the laser by intermixing harmonics of the electrical pulse with higher harmonics of the laser pulse train. We also demonstrated a new method which detects the phase error signal directly for computation of the r.m.s. timing jitter. The results are in good agreement with the conventional phase noise spectra measurements. The best r.m.s timing jitter for the freee running Ti: sapphire/SSBR laser is 7.24ps. With an optoelectronic phaselocked loop (OEPLL) and intermixing higher harmonics of the laser pulse train with the reference RF sine wave signal, the r.m.s. timing jitter calculated rrom the conventional phase noise spectra is 1.56ps. We then replace. RF sine wave signal with a 1GHz comb generator and the corresponding r.m.s timing jitter is reduced to 1.36ps, 1.26ps, 0.94ps, and 1.33ps when the 11th, 22th 33th, and 45th harmonic of the laser pulse train is used for intermixing. We design a circuit to detect the phase error signal in the time domain directly for computing the r.m.s timing jitter. The dorresponding r.m.s thming jitter is reduced to 524fs, 351fs, and 493fs when the 22th, 33th, and 45th harmonic of the laser pulse was used for intermixing.
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