What is tunable filter?

A tunable filter is an optical device that allows specific wavelengths of light to be selectively transmitted or blocked, based on adjustable parameters. By altering its characteristics, such as the refractive index or physical dimensions, the filter can be tuned to different wavelengths, making it useful in applications like spectroscopy, telecommunications, and imaging systems. These filters can be implemented using various technologies, including liquid crystals, microelectromechanical systems (MEMS), and photonic crystals.