Photonic Integrated Circuits for microwave photonics

InP-based Photonic Integrated Circuits (PICs) have found applications in the telecommunication and sensing arena because they have offered improvements in cost and function as well as size, weight and power. For microwave photonics applications, it has been found that some analog functions such as optical-phase locked loops (OPLLs) can be greatly improved and enabled with PIC technology. Primary reasons are significantly reduced path lengths that enable much higher loop bandwidths and very stable optical paths enabling low noise coherent summing of optical signals. In this paper significant advances in PIC technology will be summarized. Integrated PIC coherent receivers and phase-locked transmitter arrays using OPLLs will be reviewed. Programmable PIC microwave photonic filters will also be briefly discussed.