Study Of Dual-frequency Nd:YAG Laser Technology Using Electrically Controlled Birefringence Of Liquid-crystal

Daul-frequency laser plays an important role in optical interferometry. The synthetic wavelength of the dual-frequency laser directly affects the measurement accuracy in absolute-distance interferometry. The shorter the synthetic wavelength is, the higher the measurement accuracy becomes. Up to now, the frequency-difference of dual-frequency laser is as large as 3.4GHz, so it is of great significance to research the dual-frequency laser with large frequency-difference. In resent years, the electrically controlled birefringence of liquid crystal is widely used in displays, light valves and optical filters, more and more researchers have paid special attentions to it and shown great interests in it. The subject mainly studies the splitting phenomena of laser longitudinal mode and the transmitted resonant mode of Fabry-Perot etalon using electrically controlled birefringence of liquid crystal, so as to find a new approach to obtain the dual-frequency laser output.Based on the laser longitudinal mode splitting theory, a novel scheme of dual-frequency laser with large frequency-difference is presented using electrically controlled birefringence of liquid crystal, and the transmitted resonant mode splitting by birefringent of Fabry-Perot etalon has been analyzed theoretically. A new element of liquid crystal Fabry-Perot etalon (LCFP) is designed and fabricated, which serves as aselector and splitter of both laser longitudinal modes and Fabry-Perot etalon's transmitted resonant modes. Two different experimental systems of laser-diode (LD) end-pumped Nd:YAG laser have been set up using two different LDs, and the transmission of liquid-crystal cell have been measured. When the empty LCFP is inserted in the cavity of high-power LD pumped Nd:YAG laser, the oscillation of a single laser longitudinal mode have been observed, such a result shows that the designed and fabricated LCFP element is capable of selecting single axial mode. While an anti-reflected liquid crystal cell is inserted in the cavity of Nd:YAG laser end-pumped by the high-power LD, it is difficult to confirm weather the laser longitudinal modes have been spitted or not. The subject is summarized in this thesis and the improvement of the project has been presented. The experiences have been accumulated and the solid foundations have been laid for further research of large frequency-difference dual-frequency laser technology.