Abstract

Wavelength-selective receivers are crucial components for wavelength-division multiplexed (WDM) systems. Most dense-WDM receivers use broadband photodetectors and require an expensive and complex wavelength demultiplexer to separate the wavelengths before detection. For low-cost WDM interconnects it is desirable to use transmitters with large wavelength spacing (10~ 20 nm) and detectors with simple built-in wavelength selectivity. Figure 1(a) shows an ideal configuration where at each stage a single wavelength is dropped and detected from the WDM signal without deteriorating other wavelengths. The ideal photodetector for this configuration should have very high responsivity and no transmission in the detection band and very high transmission at other wavelengths to achieve very low insertion losses, cross talk, and increased cascadability. A simple quantum well (QW) or bulk detector with varied composition in the absorption region can not fulfill these requirements because of substantial cross talk¹ and difficulties in obtaining wavelength accuracy and selectivity.

© 1996 Optical Society of America