高频补偿倾斜电极型宽带声光叉指换能器

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～ 15 0nm厚的SiO2 /In2 O3 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 7MHz,Bragg声光带宽为 5 5 3MHz,通带斜率为 0 0 0 ,通带凹陷深度 <1 0dB。当模转换效率为 99%时 ,测得射频 (RF)驱动功率为 4 5mW ,该器件可望作为 1 15～ 1 6 5 μm红外频谱分析仪的分光器件

Wide-band Acoustooptical IDT with High-frequency Compensated Slanted Transducer Fingers

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.