Patent ID: 10845251

Abstract:
Method and apparatus for determining the wavelength of a light beam are provided. An input light beam is received, and light from the input light beam is distributed to multiple channels. At a first pair of interferometer cavities that has a first free spectral range, two of the multiple channels of light are received. The intensity of light reflected from the first pair of cavities is measured, and a first estimate of the wavelength or optical frequency of the input light beam is determined based on measurements of interference signals from the first pair of cavities and an initial estimate of the wavelength or optical frequency. At a second pair of cavities that has a second free spectral range smaller than the first free spectral range, another two of the multiple channels of light are received. The intensity of light from the second pair of cavities is measured, and a second estimate of the wavelength or optical frequency of the input light beam is determined based on the first estimate and measurements of interference signals from the second pair of cavities, in which the second estimate is more accurate than the first estimate.