We report low-loss channel waveguides in a single-crystal LiNbO3 thin film achieved using the annealed proton exchange process. The simulation indicated that the mode size of the alpha phase channel waveguide could be as small as 1.2 mu m(2). Waveguides with several different widths were fabricated, and the 4 mu m-wide channel waveguide exhibited a mode size of 4.6 mu m(2). Its propagation loss was accurately evaluated to be as low as 0.6 dB/cm at 1.55 mu m. The single-crystal lattice structure in the LiNbO3 thin film was preserved by a moderate annealed proton exchange process (5 min of proton exchange at 200 degrees C, followed by 3 h annealing at 350 degrees C), as revealed by measuring the extraordinary refractive index change and x ray rocking curve. A longer proton exchange time followed by stronger annealing would destroy the crystal structure and induce a high loss in the channel waveguides. (C) 2015 Optical Society of America
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机译：我们报告了使用退火的质子交换过程实现的单晶LiNbO3薄膜中的低损耗通道波导。仿真表明，α相通道波导的模式大小可能小至1.2μm（2）。制作了具有几种不同宽度的波导，并且4微米宽的通道波导的模式尺寸为4.6微米（2）。在1.55微米下，其传播损耗被精确评估为低至0.6 dB / cm。 LiNbO3薄膜中的单晶晶格结构通过适度退火的质子交换过程（在200摄氏度下质子交换5分钟，然后在350摄氏度下退火3小时）得以保留，这通过测量异常折射率来揭示变化和X射线摇摆曲线。较长的质子交换时间，然后进行更强的退火，将破坏晶体结构并在通道波导中引起高损耗。 （C）2015年美国眼镜学会
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