提出了一种新型的宽带声光表面波叉指换能器(SAW-IDT), 该换能器应用双梯形倾斜电极,可对单梯形倾斜电极IDT通带的高频成分进行补偿,使通带更宽更平直,并无需外补偿网络.通过计算机模拟得出IDT的优化高频补偿因子ρ=0.12及其他的优化参数.该器件以Y切X传Ti扩散LiNbO3作为光波导,以～150 nm厚的SiO2/In2O3薄膜作为声波导,声孔径W0=110 μm,叉指对数N=9.IDT的中心频率为187.7 MHz,Bragg声光带宽为55.3 MHz,通带斜率为0.00,通带凹陷深度<1.0 dB.当模转换效率为99%时,测得射频(RF)驱动功率为45 mW,该器件可望作为1.15～1.65 μm红外频谱分析仪的分光器件.

A novel broadband acoustooptical (AO) surface acoustic wave interdigital transducer (SAW-IDT) scheme is presented, by using double-tapezia-electrode IDT to compensate high-frequency component of the slanted single-trapezia-electrode IDT. It makes flatter amplitude response and wider bandwidth than those of the single-trapezia-electrode IDT. At the same time, the external compensating network is eliminated. The optimal compensating factor ρ=0.12 and other optimal parameters are found by computer simulation. In the device, Ti-Diffused YX-lithium niobate substrate was applied as optical waveguide, a SiO2/In2O3 film of thickness ~150 nm as ASW waveguide and an acoustical aperture of width 110 μm, in conjunction with N=9 finger pairs. This laboratory prototype shows Bragg acoustooptical bandwidth is 55.3 MHz at 187.7 MHz, its passband slope is 0 and hollow depth is less than 1.0 dB. The RF drive power is measured to be 45 mW at mode-conversion efficiency of 99%. The device is expected to be a integrated optics acoustooptical spectroscopein spectrometer for 1.15~1.65 μm.