A high density WDM optical receiver using an integrated detector array

Wavelength division multiplexing of closely spaced channels (HDWDM) in direct detection optical systems is recognised as an attractive way of distributing broadband services and flexible capacity in networks for multiterminal working. In many of these systems the demultiplexing component is based upon an optical diffraction grating with fibre input and outputs. It is shown that an alternative, and in many ways superior, implementation results from replacing the array of output fibres by an array of optical detectors. This arrangement gives a number of distinct advantages over the fibre coupled outputs: a more compact realisation better suited to matrix switching at low electrical levels; very much higher channel bandwidth to spacing ratio alleviating the need for tight wavelength control; and reduced insertion loss