Research of surface acoustic wave acousto-optic effect - art. no. 68381E

A strengthened acousto-optic (AO) coefficient of piezoelectric crystal is defined. AO coupled-wave equations of surface acoustic wave (SAW) to plane guide optic wave (PGOW) and to fiber guide optic wave (FGOW) are given respectively. A diffractive efficiency formula of SAW PGOW AO interaction and a back-wave efficiency formula of SAW FGOW AO interaction are given. The formulas indicate that under condition of weak AO interaction intensities of the diffractive wave and the back-wave are proportional to ultrasonic powers. Lithium Niobate (LN) is optimum crystal of SAW PGOW AO device, quartz is optimum crystal of SAW FGOW AO device. A SAW PGOW AO modulator using LN and a SAW FGOW AO modulator using quartz are designed and manufactured. Some curves of the diffractive wave power and the back-wave power vs. electric powers of signals driving the modulators are measured. SAW AO modulators have many advantages, for example small volume, good stability, low energy consumption and it is easy to integrate. The modulators can be used as intensity modulators. The modulators have applications in optic communication and real time signal processing.