成果報告書詳細
管理番号20160000000673
タイトル*平成27年度中間年報 国際研究開発・実証プロジェクト/コファンド事業 フランスBpifranceとの国際研究開発・実証事業 ライダー用可視・紫外レーザ光源の研究開発  
公開日2016/8/18
報告書年度2015 - 2015
委託先名株式会社オキサイド
プロジェクト番号P14005
部署名IoT推進部
和文要約
英文要約Title: Japan-France Bilateral R&D Cooperation Program/ Visible and ultraviolet pulsed fiber laser development for LIDAR system (FY2015-FY2017) FY2015 Annual report

1. Research and development of frequency convertor for small size and low cost green laser for LIDAR.
In order to design mass production process for frequency conversion device, we designed photomask of PPMgSLT device and investigated the effective procedures of polishing and coating. In order to design optical configuration, we investigated focusing of the 1064nm laser, device length, and QPM chirping patterns by taking robustness and components of the module into consideration. We tested the fundamental properties of 5mm-long PPMgSLT under several focusing and confirmed the optimum condition of the 50% conversion efficiency without any distortion of green light. For the QPM chirping pattern device, we confirmed the expansion of temperature tolerances by increasing the chirping rate. Based on above measurements, we applied them to Keopsys’s laser. We checked conversion several optical parameters by changing the device length and found the optimum condition of more than 50% conversion efficiency with 2 to 3 mm-long PPMgSLTs. For the chirping device, we found the optimum design for more than 50% conversion efficiency with 20 degree-C temperature tolerances. Those data are applied for the convertor design.
2. Research and development of frequency convertor for UV laser for LIDAR.
LBGO crystals were grown by the RF-heated Czockralski method. Single crystals were achieved after several growth conditions were examined. The yield of the single-crystalizing is now approximately 20 to 30 %. Based on our present results, we found that that the crystals had difficulty in growing along radial direction of the crystal and poly-crystallization was frequently appeared. We measured temperature dependence on melting and/or growing speed of seeds and temperature distribution of the present growth furnace. We found that temperature range between melting of the seed and growing crystal on the seed was extremely large as compared to other materials and high supercooling temperature more than 5 degree-C was needed to start the growth. The high supercooling is one reason for ploy-crystalizing. We also found that the temperature gradient ratio between radial direction and pulling direction was about 1:2. The temperature gradient ratio was revealed that the crystal is easily grown along the radial direction. The temperature distribution of the present growth furnace is another reason for ploy-crystalizing. Testing growth conditions by using new construction of the furnace is needed in order to increase the yield of the single-crystalizing. We also prepared another furnace for LBGO crystal with large diameter to achieve the longer PP-LGBO devices. We also developed single domain poling condition by selecting optimum setup and environment and the yield was increased from 20% to 80%. For THG and FHG materials, we grew LBOs and BBOs with optimized melt condition. We are now approaching the characterization of those grown materials from the point of laser properties.
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