Fabrication of Surface Acoustic wave resonator as Acousto-optic Modulator

Acousto-optic modulation techniques are gaining edge in diverse applications in the area of agriculture, entertainment and defense. Present work focuses on indigenously developed pump probe technique to study the acousto-optic modulation using surface acoustic wave (SAW) device. For this study, SAW device has been fabricated on ST-cut quartz that is an optically nonlinear piezoelectric material. Coupling of acoustic wave with optical wave has been monitored and a visible modulation in the intensity of probe laser beam has been obtained. A clear shift in the value of probe intensity (∼12 μW) is observed when surface acoustic waves are excited. Angular rotation of the fabricated SAW device under pump probe microscopy shows the periodicity of the nonlinearity in substrate while acoustic wave is propagating in it. The effect of variation in the intensity of pump laser beam on the acousto-optic modulation is also studied. The acousto-optic modulation behavior observed in surface acoustic devices in the present study demonstrates the possible application in telecommunication for signal modulation and in spectroscopy for frequency control.