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Theoretical And Experimental Investigation Of All-solid-state Nd:YAG Dual-wavelength Laser At473nm And946nm

Posted on:2014-02-08Degree:MasterType:Thesis
Country:ChinaCandidate:X Q LiFull Text:PDF
GTID:2268330401962464Subject:Optics
Abstract/Summary:PDF Full Text Request
For solid-state blue lasers there exist numerous applications, such as color displays, high-density optical data storage, and underwater communication. In addition, Si photodiodes with quantum efficiencies over99%are available at946nm. Hence the use of Nd:YAG laser at946nm and Si photodiodes will reduce the detection loss in the generation of squeezed light. So the473nm laser and the946nm laser have attracted much attention.Efficient lasing on this4F3/2-4l9/2transition at946nm is a quasi-three-level system, which has the need for high pump deposition density to achieve population inversion. This in turn leads to very strong thermal effects. Among all thermal effects, thermally induced birefringence is a knotty phenomenon in particular. What’s more, the presence of ETU effects gives to a significant extra heat in the laser crystal. So in our paper, the thermal effect is theoretically investigated by including energy-transfer upconversion (ETU) effects into the space-dependent rate equations. At the same time, the three-mirror folded cavity was designed to realize the dual-wavelength output at473nm and946nm. The research in detail is as follows:1. The influence of ETU effect on thermal effects in Nd:YAG946nm laser is theoretically studied, by solving the space-dependent rate equations including energy-transfer upconversion (ETU) effects.2. An all-solid-state dual-wavelength laser at473nm and946nm is designed considering the influence of thermal effects. By the way of composite crystal Nd:YAG end-pumped by a laser diode at the central wavelength of808nm, the three-mirror folded cavity is designed to realize laser output. The periodically poled crystal PPKTP is employed as intracavity frequency doubling crystal. Given the existence of thermal depolarization of Nd:YAG crystal, the Brewster plate is inserted into the cavity as a polarizer and output coupler of fundamental laser.3. For the existence of thermal depolarization losses in Nd:YAG laser crystal, we introduce two ways to compensate the thermally induced birefringence. Using Jones matrix, the principle and comparison of the two methods are studied theoretically and experimentally. The experiment is carried with a quarter-wave plate to compensate the loss resulting from the thermal induced birefringence.
Keywords/Search Tags:Dual-wavelength output at473nm and946nm, Energy-transfer upconversion, thermal depolarization loss, Output transmission, Compensation of thermal inducedbirefringence
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