Optical distributed-feedback channel-dropping filters: design and fabrication

The integrated resonant channel-dropping filter is used in wavelength-division multiplexing (WDM) systems. The integrated filters are constructed by electron beam etching quarter-wave shifted distributed feedback (QWS-DFB) gratings on top of integrated rib waveguides. A QWS-DFB structure allows for a single optical resonance in the underlying waveguide. Such QWS-DFB structures can interact with optical signals in such as way as to selectively transmit, reflect, or detect the signals that are resonant with the structure. These frequency-selective operations are well suited for a variety of communication applications.<
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