An acousto-optic modulator (AOM) is a device that uses sound waves to control light. It works by creating a periodic change in the refractive index of a material, which can diffract and shift the frequency of a light beam. This allows for precise modulation of the intensity, frequency, and direction of the light, making AOMs useful in various applications like telecommunications and laser systems. AOMs are commonly used in conjunction with lasers, such as solid-state lasers or fiber lasers, to achieve rapid and accurate control over the output. They are essential in fields like optical communication, spectroscopy, and laser printing, where precise light manipulation is crucial for performance and efficiency.