Photonically-Enabled Software Defined Radios for Broadband Applications

Software defined radios (SDRs) have redefined many areas of modern electronics, from enabling reconfigurable communications to rapid prototyping of new electronic support concepts. However, current implementations of SDRs are limited by the underlying electronic approaches used to realize them. Herein, we describe a novel photonically-enabled SDR (PESDR) that utilized the inherently broadband nature of signal generation, mixing, and routing in optics to enable extremely broadband SDRs with wide frequency tunability and deployment flexibility. Using optimized versions of optical modulators and photodiodes, first developed for the telecommunications industry, efficient conversion to and from the optical domain is possible and optical fiber and photonic integrated circuit routing provides low-loss, low-SWaP form factors for SDR realization. Using experimentally-validated injection locking techniques, PSI has been able to realize tunable optical paired sources (TOPS) that lock two laser cavities with a precise frequency offset and replicate linewidth and noise between the two lasers. Thus, when these two lasers, or any modulated signals deriving from these lasers, are beat together on a photodiode, a precise sub-1Hz linewidth tone is generated in the electrical domain. These locked lasers can then form the basis for a widely-tunable, software-defined transmit and receive channels that can be modulated, routed, and