Photonic integrated circuits: research curiosity or packaging common sense?

The potential of photonic integrated circuits (PICs) for meeting the requirements of high-connectivity optical communication architectures (where there is a variety of cascaded, interconnected optical devices at each station) at a reasonable cost is discussed. PICs refer to the monolithic (single-substrate) integration of optically interconnected guided-wave devices. PIC technology replaces the separate, sequential alignment of single-mode fiber interconnections between the discrete devices with lithographically produced single-crystal waveguides, eliminating the cost of individual alignments through a wafer-scale batch process and providing a lower-loss connection, a low-reflection connection, and a very robust, small package. To illustrate the application of PIC techniques, a balanced heterodyne receiver, a wavelength-division-multiplexing source, and tapered waveguide output couplers are considered.>