| Summary: | 博士 === 國立交通大學 === 光電工程所 === 87 === In this thesis, we studied several important topics on nonlinear optical spectroscopy and microscopy. As for nonlinear optical spectroscopy, we studied how a phase-retrieval procedure based on the maximum-entropy method is applied to the coherent nonlinear optical spectra. The error-phase behavior was found to be influenced by the interference between the resonant part and a nonresonant background. This result implies that the estimation of the error-phase, the key-step in the whole phase-retrieval procedure, will depend on the nonresonant-background contribution. We also discovered a new application of the maximum-entropy phase-retrieval procedure. This method can solve the phase retrieval problem in the deconvolution process for nonlinear optical spectra measured with transform-limited light pulses. On the other hand, we also presented the potential of the infrared-visible sum-frequency spectroscopy in studying the molecular chirality. An experimental spectra from a chiral liquid crystal showed that the vibrationally stretching mode of a methyl group will be affected by a nearby chiral center. Therefore the local mirror-asymmetry can be measured by using methyl group as a probe. The normalized intensity difference between left- and right-hand circularly excitation in the measured spectrum was found to be as high as 50%. As for the nonlinear optical microscopy, our studies were focused on the second harmonic microscopy. We constructed a pico-second diode-pumped solid-state-laser as the exciting source for the second harmonic microscope. We applied the second harmonic microscopy to the characterization of a in-plane electric-field-poled polymer and a periodically poled lithium niobate crystal. From the recorded second harmonic intensity pattern, we can deduce the information about the local orientation of the nonlinear optical molecule in the poled polymer and the inverted domain structure in a periodically poled lithium niobate crystal.
|
|---|
