| 摘要 |
A comb splitting system demultiplexes and/or multiplexes a plurality of optical signal channels at various wavelengths. The comb splitting system has at least two interconnected successive stages of wavelength division multiplexers (WDMs). The first stage comprises a Fourier filter that communicates bands of channels to respective WDMs of the second stage via suitable optical paths. Each of the bands has a plurality of the individual channels that are separated by at least one other of the channels. Each second stage WDM, which is allocated to a particular band, is interconnected to respective optical paths for carrying one or more individual channels. Furthermore, in accordance with a significant feature of the present invention, the passband width and periodicity (i.e., free spectral range) associated with the first stage Fourier filter are smaller than the passband width and periodicity associated with the second stage WDMs. Consequently, the second stage WDMs can be less expensive and physically smaller than the first stage WDM. Moreover, later stages can tolerate larger fabrication errors, do not require birefringence compensation, and can tolerate full environmental temperature variations without feedback control in the central office. In accordance with another feature of the present invention, a double filtering scheme can be utilized to reduce crosstalk between channels.
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