A 1:4 demultiplexer for 40 Gb/s fiber-optic applications

The demultiplexer (DEMUX) is a critical component of a fiber communication system. In order to satisfy increasing demands for data, fiber systems will employ several wavelengths carrying 40 Gb/s data in the near future. The requirements for such systems dictate that the DEMUX handle at least 4 channels of 10 Gb/s SONET/SDH data. The challenge is to build a 1:4 DEMUX that is both manufacturable and cost-effective to be integrated onto a receiver board. The authors describe a monolithic four-channel DEMUX for 40 Gb/s applications which uses an AlInAs/InGaAs HBT technology from a commercial foundry. Measurements demonstrate 40 Gb/s operation for 0.3 Vpp single-ended data input and 0.6 Vpp differential clock input.