Photonics for RF Front Ends

In this article, some of the latest technology advancements in microwave photonics, in particular those related to the RF front end were reviewed. The generic salient features and issues associated with microwave photonic links were provided. It is shown that optical amplification and high power photodiodes can lower the noise figure of these links. Photonic downconversion and microwave-to-digital systems and potential photonic simultaneous transmit and receive configurations were also reviewed. Opto-electronic oscillator technologies to create low phase noise RF signals and also the efficient integration of photonic components directly with antennas were examined. While progress is expected to continue in the near future to improve on the efficiency and performance of microwave photonic components and subsystems, significant future challenges will be dominated by activities involving the integration of the technologies discussed into microwave systems to fully realize the benefits discussed. This will require the active involvement and education of RF and microwave system designers to the benefits and interface challenges of microwave photonic systems, as well as the different packaging, powering and controls required. All the technologies reviewed are potential enabling technologies for photonic implementations of RF front ends and point to an expectation for many future improvements and new capabilities enabled.