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Jordan Cox
2007 U.S. Student
Advisor: Martin C. Richardson
"Investigation of Notchless In situ μ-Raman Spectroscopy"
Micro-Raman spectroscopy is a powerful method for analyzing the bond structure of matter. The Laser Materials Processing group uses a femtosecond pulsed laser to create waveguides in Chalcogenide and Oxide glasses. Raman spectroscopy is used to identify changes in the glasses before and after laser irradiation. More effective is in situ Raman spectroscopy, tracking the changes in the glass in real time. The objective of this project was to develop a μ-Raman spectrometer system without the necessity of expensive notch filters. Rayleigh scattering, the primary scattered light that has the same wavelength as the pump light, is one million times more intense than the Raman scattering. For this reason, notch filters have been traditionally used to suppress only the strong pump light to increase the signal-to-pump ratio and allow for the detection of Raman scattering. The project described here employs a laser with a very narrow bandwidth to obtain the data. In this way the necessity of the notch filter is bypassed while maintaining the detection of Raman scattering. Future work includes the creation of a Raman system that tracks changes in situ. ...full text
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