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UBC Theses and Dissertations

New methods of coherent anti-Stokes Raman spectroscopy based on broadband pulses Xu, Xiaoji

Abstract

The research work of this Ph.D. thesis is centered on coherent anti-Stokes Raman spectroscopy (CARS) with broad band coherent pulses. After a mathematical derivation of the formula that is responsible for CARS, four new approaches were proposed. The first method of Noise-autocorrelation spectroscopy with coherent Raman scattering utilizes spectral noise to reveal vibrational level spacings through autocorrelation. Its variation of Narrowband spectroscopy by all-optical correlation of broadband pulses, uses the technique of optical processing based on noisy probe pulse of special shape to obtain high resolution CARS spectra. The method of complete characterization of molecular vibration, can measure the phase of laser induced vibration through amplitude and phase retrieval on a time-frequency spectrogram. It is also a high resolution method. The final method Background free coherent Raman spectroscopy by detecting spectral phase of molecular vibrations is the spectroscopic application of detected spectral phase of laser induced vibration.

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