摻雜氧化鎂鈮酸鋰之帶狀波導大溫度頻寬綠光雷射晶片之研製

Abstract

摘要 本論文以摻雜氧化鎂鈮酸鋰為基板，利用啁啾型光柵在其上製作長為5mm之多週期反轉結構帶狀波導，目的為利用1064nm基頻光耦合至光波導，經由準相位匹配倍頻產生532nm綠光，並量測其輸出之溫度頻寬和光功率。 波導製程方面本論文使用鋅鎳共同擴散式波導與鎵擴散式波導，其中鋅鎳共同擴散式波導線寬為160μm，膜厚100nm，在擴散溫度880℃下擴散3小時，可導TM和TE模態光，符合前人所作之極化與製程相依性 ; 鎵擴散式波導線寬為160μm，膜厚120nm，在擴散溫度980℃下擴散2小時，可單導TM模態。 本論文在綠光量測方面，以最大能量8mW之1064nm基頻光入射於晶片之波導，未製作波導之晶片，其溫度頻寬為60℃，倍頻轉換效率為9.9%。鋅鎳共同擴散式波導，其溫度頻寬增加為80℃，倍頻轉換效率提高為15.4% ; 鎵擴散式波導，其溫度頻寬增加為85℃，倍頻轉換效率提高為13.9%。此結果說明了在週期性極化反轉結構上加上光波導，也就是增加了光場侷限性，有助於溫度頻寬和倍頻轉換效率的提升。

Abstract Magnesium-doped lithium niobate substrates are used for the design and fabrication of waveguides on a 5 mm long segment-chirped grating structure. Green laser of wavelength 532 nm is obtained by the quasi-phase matching second harmonic generation (QPM-SHG), when launched with an incident laser of wavelength 1064nm. On the part of waveguide fabrication, two waveguides are fabricated by zinc-and-nickel co-diffusion and gallium diffusion in this thesis. The zinc-and-nickel co-diffusion waveguides have linewidth of 160 μm and film thickness of 100 nm, which were diffused for 3 hr at 880 ˚C. The gallium diffusion waveguides have linewidth of 160 μm and film thickness of 120 nm, which were diffused for 2 hr at 980 ˚C. TM and TE modes are supported in the zinc-and-nickel co-diffusion waveguides, but only TM modes are supported in the gallium diffusion waveguides, which agrees quite well with those reported previously. On the part of green laser measurement, an incident laser of maximum power 8mW with wavelength 1064 nm is launched into the sample. The sample without waveguides have temperature bandwidth of 60 ˚C, and green laser conversion efficiencies of 9.9%. The zinc-and-nickel co-diffusion waveguides have a larger temperature bandwidth of 80 ˚C, and a higher green laser conversion efficiencies of 15.4%. Similarly, the gallium diffusion waveguides have a larger temperature bandwidth of 85 ˚C, and a higher green laser conversion efficiencies of 13.9%. Experimental results show the temperature bandwidth and conversion efficiencies are both increased owing to the proposed waveguide structures provided better optical confinement.