Andy Resnick said:In acousto-optic devices, the permittivity changes due to changes in the density. Do you have a link to a specific device?
Permittivity is a measure of a material's ability to store electric charge and influence the electric field. In the context of electro-optic modulation, varying permittivity refers to changing the permittivity of a material in order to manipulate the electric field and affect the transmission of light through the material.
Low-frequency modulation refers to varying the permittivity of a material at a low frequency, typically in the range of a few Hertz to a few kilohertz. This is significant because it allows for precise and efficient manipulation of the electric field without causing any unwanted side effects such as heating or electrical breakdown in the material.
Electro-optic modulation works by applying an electric field to a material with varying permittivity. This electric field causes a change in the material's refractive index, which in turn affects the transmission of light through the material. By controlling the strength and frequency of the electric field, the amount of light passing through the material can be modulated.
Low-frequency electro-optic modulation has a wide range of applications, including telecommunications, optical computing, and laser technology. It is used for signal processing, switching, and controlling the intensity, phase, and polarization of light in various optical devices.
Some common materials used for low-frequency electro-optic modulation include lithium niobate, potassium dihydrogen phosphate, and lead zirconate titanate. These materials have high permittivity and can be easily manipulated by an external electric field, making them ideal for use in electro-optic devices.