Tunable filter and the method for making the same

摘要

A tunable filter and its manufacturing method are disclosed. Interference of two laser beams defines the grating pattern required by the filter to make a micro grating with a period as small as several hundred nanometers on a polymer film. As the refractive index of the polymer film changes with the temperature, one can control the temperature to adjust the wavelengths of optical signals that the micro grating can reflect.