A wavelength sensor coupled to the drop filter to monitor the selected frequency to which the drop filter arrangement has been tuned.

The band drop filter has a drop range selected to drop selected ones of the wavelength channels used by the WDM transmitters in the satellite nodes.

A photonic circuit includes a tunable drop filter arrangement that includes a plurality of resonators.

This allows the use of light signals of wavelength channels outside the drop range of the band drop filter for carrying information in the network.

A single band drop filter (35) is arranged in the main node to receive the light signals from the satellite nodes.

The beverage extraction filter comprises a filter unit (40) where coffee powder is housed and a planar lid unit (41) mounted to the top section of the filter unit (40).

An edge extraction section (66) of a contour image generating section (22) generates an edge image of an input image (62) by means of an edge extracting filter or the like.

The present invention is a method and apparatus for a rotating, tunable, holographic drop filter connected to a fiber optic source.

The bottom (6) and the lid (4) can both be removed from the cylinder (2) in order to open the brewing chamber (8), a water inlet (26) being located in the lid (4) and an extraction filter and a beverage outlet being located in the bottom (6).

The drop filter arrangement is tuned to remove a selected frequency from an input data stream from a waveguide.

In another, methods for optical filtering using an SPPC waveguide-coupled cavity drop filter are disclosed.