acousto optic modulator efficiency means Diffraction Efficiency.
Diffraction Efficiency
For small acoustic powers, the diffraction efficiency is proportional to the acoustic power; for higher powers, it saturates. For sufficiently high acoustic power, more than 50% of the optical power can be diffracted – in extreme cases, even more than 95% diffraction efficiency is achieved. High diffraction efficiencies are easier to achieve for short optical wavelengths.
In many cases, a high diffraction efficiency is important. For example, this matters when using the AOM as a Q switch in a high-gain laser, and even more so for cavity dumping. The required RF power influences both the electric power demands and cooling issues. It is lower for acousto-optic materials with high elasto-optic coefficients.
Note that the diffraction efficiency depends nonlinearly on the acoustic drive power. For an effectively linear response, a suitable pre-distortion of the drive signal is required.
Traditional acousto-optic (AO) devices based on bulk crystal materials have weak energy confinement abilities for both photons and phonons, leading to a low AO interaction strength. Compared with bulk materials, photonic integrated circuits (PICs) allow surface acoustic waves (SAWs) to be well confined within the thin film used to disturb the guided light waves, exhibiting a high energy overlap within the wavelength scale.
More acousto optic modulators are developed in the year of 2020 – 2022 . There are 532nm, 780nm and other visible laser light acousto optic modulator.