Interleaver, filter included therein, and interleaver system

摘要

The present invention relates to an interleaver and others with a transmission spectrum excellent in isolation between signal channels and flat near each channel wavelength. The interleaver is provided with an input port for receiving a signal of multiple channels, and first and second output ports for outputting signals of first and second channel groups, respectively, separated from the signal of multiple channels. Each of transmission spectra of output light from the first output port and output light from the second output port has such flatness that a difference between a maximum transmittance and a minimum transmittance in a wavelength range of ±0.06 nm centered about each signal channel wavelength falls within 0.4 dB, preferably within 0.2 dB, and crosstalk between adjacent signal channels is controlled to -20 dB or less, preferably to -30 dB or less.