不同晶体对称类的栅条反射系数的理论与实验研究  

A theoretical and experimental study on strip reflection coefficient of different crystal symmetry class

作　　者：徐方迁[1] 何世堂[1] 

机构地区：[1]中国科学院声学研究所,北京100080

出　　处：《声学学报》2005年第1期26-30,共5页Acta Acustica

摘　　要：对四方4／mmm、六角6／mmm和三角3m等晶体栅条反射系数进行了详细理论分析,给出具体的数学表达式,不同于已有的立方m3m栅条反射系数理论计算公式。根据理论分析结果给出112°旋转X切Y传LiTaO3基片上的铝短路反射栅和沟槽的反射系数。用实验方法研究了112°LiTaO3基片上的沟槽填铝短路反射的反射特性,得到了内反射为零的条件。证明了在112°LiTaO3基片上可用沟槽填铝单指结构实现无内反射的结论。将上述结果应用于单指无内反射滤波器的研制,得到了中心频率255 MHz、带宽约10 MHz、带内畸变小于0.4 dB的带通滤波器。The closed-form expressions of strip reflection coefficients of tetragonal 4/mmm, hexagonal 6/mm and trigonal 3m crystal etc are derived, which are different from that of cubic m3m crystal published. The reflection coefficients for short-circuited Al grating and groove grating on 112° rotated X-cut Y-propagation LiTaO3 are then given by our theory. The reflection property of the groove grating on 112°LiTaO3 in which short-circuited Al grating was placed has been studied by an experimental method and the condition that internal reflection is close to zero was achieved. It concluded that the structure of single finger without internal reflection can be realized by placing short-circuited Al strip in groove grating on 112°LiTaO3 and thereafter a pass-band filter with central frequency 255 MHz, bandwidth about 10 MHz, pass-band ripples less than 0.4 dB are yielded by utilizing those results in the study of single finger without internal reflection.

关 键 词：LITAO3 反射系数 晶体 基片 对称 立方 证明 带通滤波器 中心频率 反射特性 

分 类 号：O73[理学—晶体学]