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|Title:||STUDY OF COMPACT AND EFFICIENT DIODE PUMPED SOLID STATE GREEN LASERS FOR DISPLAY APPLICATION|
|Abstract:||Due to the long lifetime, high directionality, and narrow spectral linewidth, laser-based displays have several advantages over other display technologies, such as high brightness, low maintenance cost and vivid color. In recent years, laser displays have attracted a lot of attention from academia and industrial community, but a number of difficulties prevent further commercialization of laser displays. The main obstacle is the speckle noise caused by the high coherence of lasers, especially in the green region, because the wavelength of commercial watt-class LD is still too short, > 530 nm DPSS green laser need to be employed to improve the image’s color quality and further speckle reduction. Since DPSS green lasers are still essential for display application, their miniaturization is necessary for pico-projection system and the field sequential modulation is needed as well. However, the modulation properties of the compact DPSS green module have not been studied yet. In this dissertation, the field sequential modulation properties of a compact Nd:YVO4/MgO:PPLN green laser module was investigated. Its output performance under a modulation condition were studied and analyzed. Furthermore, a number of single-(dual-) wavelength continuous wave green DPSS lasers are proposed and demonstrated for the purpose of speckle reduction and color improvement. An intra-cavity frequency doubling configuration was used to achieve efficient nonlinear conversion and smaller dimensions. Specifically, a 531.5 nm was built based on Nd:GdVO4 and MgO:PPLN crystals, it has a output power of 1.9 W with an O-O efficiency of 37%. A compact 540 nm laser was achieved by using Nd:YAP and LBO, in which a 0.8 W output power was achieve with an O-O efficiency of 20%. Watt-class 542 nm / 543 nm Nd:YVO4/MgO:PPLN green lasers was achieved by customized cavity coating design since weaker fluorescence peaks are used as fundamental light. An O-O efficiency of 22% and 35% was obtained, which are the highest O-O efficiencies achieved so far to the best of our knowledge. In addition, an orthogonally polarized dual-wavelength (542 & 543 nm) was realized by using a conventional Nd:YVO4 crystal and two MgO:PPLN crystals. An optical-to-optical (O-O) efficiency as high as 15.3% was achieved when the powers of the two emission wavelengths were equal. This is the first time that a dual-wavelength orthogonally polarized visible solid state laser is achieved. Moreover, the speckle reduction performance of the proposed lasers was studied as well. It shows that the SCR value is effectively reduced by blending different green wavelengths together, which agree well with the theoretical expectation. Generally, those lasers have features of efficient, compact, and low cost which are suitable for laser display application. At last, a tri-wavelength wavelength blending method was proposed and studied. A 523 nm green LD, 532 nm and 543 nm green DPSS lasers are employed for wavelength blending purpose. It shows that lower SCR was achieved where all three wavelengths are involved, which agrees well with the theory. Moreover, optimal color performance was maintained as a result of the employment of 543 nm laser, which was the purpose for developing long wavelength green laser.|
|Appears in Collections:||Open Access Dissertations and Theses|
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