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Self-heterodyne beating of dual polarization modes in a single-frequency, microchip holmium,thulium:YAG laser and injection -seeding of a Q-switched oscillator

Posted on:1995-07-11Degree:Ph.DType:Dissertation
University:University of South FloridaCandidate:He, ChuanFull Text:PDF
This dissertation presents results of a study on the development of an injection-seeded flashlamp-pumped, Q-switched Ho,Tm,Cr:YAG 2.1 ;A flashlamp-pumped Ho,Tm,Cr:YAG laser was developed and modified for Q-switched operation. The maximum output energy for TEM;After a high-resolution spectral study was made, it was determined that the supposedly CW single-frequency microchip Ho:YAG laser did not operate on a single frequency, but actually operated on two, slightly elliptical, dual-polarized orthogonal laser modes, which could not be detected by conventional spectroscopic techniques (i.e. spectrometer, Fabry-Perot). These two orthogonal modes were separated in frequency by approximately 12 MHz, and when photodetected, produced a 12 MHz self-heterodyne beat signal. Our studies indicated, for the first time to our knowledge, that the dual-polarization modes were produced by residual stress in the Ho:YAG laser crystal, which caused the normally isotropic YAG crystal to become slightly birefringent. It was found that one of the dual polarization modes could be eliminated through use of an external polarizer and a quarter-wave plate, but that small changes (;Lastly, the wavelength of the microchip Ho,Tm:YAG laser could be tuned continuously by changing either the crystal temperature or pump laser power. Crystal temperature tuning provided 20 GHz tuning range and pump power tuning provided 4 GHz fine tuning range. In order to study the wavelength tuning of the microchip laser, the laser was used as a tunable optical source to conduct preliminary laboratory absorption measurements of CO...
Keywords/Search Tags:YAG, Microchip, Q-switched, Modes
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