Optical filter, method of controlling transmission wavelength thereof, and optical receiver using the method

摘要

An optical filter selectively receives a signal of a desired optical frequency from a plurality of optical-frequency-division multiplexing signals. Additionally, a transmission wavelength of the optical filter can be controlled using an optical receiver which includes the optical filter. The optical filter can perform a narrow-band optical filtering and permit, in optical communication systems using the optical filter, the transmission wavelength range of the optical filter to follow up a change in the wavelength of a light source. The optical filter selectively receives a signal of a desired optical frequency from a plurality of optical frequency-multiplexed signals. Additionally, the optical filter includes a first optical filter having a transmission band characteristic with a single peak in a desired band and a half band width of a desired amount of attenuation in the transmission band equal to or smaller than about two times a channel interval of the multiplexed light signals. A second optical filter, also in the optical filter, has a periodic transmission characteristic, an odd multiplication of a half of a free spectral range of the periodic transmission characteristic being equivalent to the channel interval of the multiplexed signals. The transmission band of the first optical filter matches with a transmission peak of the second optical filter.