From Event: SPIE LASE, 2019
Most of the nonlinear optical material for ultraviolet generation are borate material such as LBO, BBO, and CLBO. There are the intrinsic disadvantages of those UV devices such as walk-off and hygroscopicity. As a result, the laser system based on those devices always require a special beam shape treatment and an anti-humidity control during storage and in operation. On the other hand, quasi phase matching devices are very attractive since there are no requirement of beam shaping. We focus on periodically poled LaBGeO5 (PP-LBGO) device since it is QPM structure and transparent at UV region. In addition, even it is borate crystal, it does not have hygroscopicity. Therefore, it is easy to treat in the fabrication process and assembling phase. In this paper, fabrication of PP-LBGO for 266nm generation was demonstrated with the first order QPM structure. The periodicity of the first order QPM for 266 nm generation from 532 nm is approximately 2.1 micrometer. The thickness of 0.3 mm LBGO plates are prepared. The electrode pattern was created on the plate. Several different electrode size and poling conditions were investigated. Finally, we successfully fabricated 2.1 micrometer periodically poled structure with 0.3 mm thick device with 10 mm in length. Its aspect ratio of periodic structure was achieved approximately 300. By using fabricated device, the better conversion efficiency for 266 nm generation was confirmed than former 2nd order PP-LBGO device by using pulsed 532 nm laser.
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Junji Hirohashi, Koichi Imai, Shunsuke Watanabe, Mitsuyoshi Sakairi, and Yasuhiro Tomihari, "Fabrication of PP-LBGO device for 266nm generation with the 1st order QPM structure (Conference Presentation)," Proc. SPIE 10902, Nonlinear Frequency Generation and Conversion: Materials and Devices XVIII, 1090206 (Presented at SPIE LASE: February 05, 2019; Published: 4 March 2019); https://doi.org/10.1117/12.2514795.6008597016001.
