Red/Blue Band Filter

The C Band Red/Blue Filter(bandsplitter) is a thin film filter micro optics device used to separate or combine Red band wavelength signals and Blue band wavelength signals in C band range in single fiber Bi-directional DWDM systems and high power amplifier systems.

The device is a three-port device. One port is called the”Common.” The other two ports provide the conduit for the two wavelength bands. The two bands are the Blue band (λ<1543 nm) and the Red band (λ>1547nm). One band goes thru the Reflect band leg, and the other band which requires the highest isolation goes thru the Pass band leg.

The R/B Band Filter may be used in several ways. The device can be used as a band combiner or a band splitter. As a combiner, the bands are combined in the filter and sent to the Common leg. Or, as a splitter, the both bands are fed from the Common leg, and split to the corresponding leg. Typically, however, the device is used as a two-way (i.e. bidirectional) WDM. One band is sent to the Common leg, while the other band is delivered from the Common leg.

In a DWDM module, which uses a Red/Blue filter, a Mux may be combined with a Demux. For example, the Mux combines DWDM channels in the Red band, while the Demux separates DWDM channels in the Blue Band. Using a Red/Blue filter, one can combine the Red Transmit channels and the Blue Receive channels onto a single fiber.