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已采用体波声延迟器件的在晶体上沉积氧化锌压电换能器的成熟工艺来制作微波声-光器件。与粘结薄片压电换能器在高频工作时所遇到的基本困难不同,溅射氧化锌换能器在高频能很好地工作,但却碰到了膜太厚的问题(>10微米)。当频段限制在200兆赫-18千兆赫时,传播纵体波的氧化锌膜能很好地工作。氧化锌换能器的沉积不适用于某些具有高声-光品质因素的材料,如钼酸铅和二氧化碲,但是与铌酸锂、钮酸锂、三氧化钛、铌酸钠钡、熔石英、钇-铝石榴石、水晶和兰宝石配合能很好地工作。用氧化锌换能器能获得宽带宽。用铌酸锂和钽酸锂为声-光材料制作了带宽大于1千兆(3分贝)的声-光器件。其中心频率从2.6-6.5千兆赫。1千兆带宽元件的换能器转换损耗(入射射频信号到声信号的总损耗,包括匹配网络损耗)小于10分贝。在此,介绍几种用于腔倒空器的微波声-光器件(目前已生产)的例子。
Microwave acousto-optic devices have been fabricated using a sophisticated process of depositing a zinc oxide piezoelectric transducer on a crystal with a volume acoustic delay device. In contrast to the fundamental difficulties encountered when bonding thin-film piezoelectric transducers operate at high frequencies, sputtered ZnO transducers work well at high frequencies, but run into the problem of too thick films (> 10 Micron). Zinc oxide films that propagate longitudinal waves work well when the band is limited to 200 MHz -18 GHz. Deposition of zinc oxide transducers is not suitable for certain materials with high acoustic-optical quality factors such as lead molybdate and tellurium dioxide but with lithium niobate, lithium niobate, titanium oxide, barium sodium niobate, Fused silica, yttrium-aluminum garnet, crystal and sapphire work well. Wide bandwidth is achieved with zinc oxide transducers. Acousto-optic devices with a bandwidth of more than 1 gigabit (3 dB) were fabricated using lithium niobate and lithium tantalate as acousto-optic materials. Its center frequency is 2.6-6.5 GHz. Transducer conversion loss (total loss of incident RF signal to acoustic signal, including matched network loss) for 1 Gigabit bandwidth components is less than 10 dB. Here, several examples of microwave acousto-optic devices (currently produced) for cavity emptyors are presented.