Reconfigurable Local Oscillator for Coherent Optical Detection

The innovation expands the range of signals that coherent optical receivers can detect. Unlike traditional systems with fixed LOs, this approach allows real-time adjustments to an LO’s properties, such as frequency, phase, polarization, amplitude, spatial mode, or timing, to better match incoming signals. These adjustments improve measurement accuracy and signal recovery in various scenarios, such as shifting heterodyne frequencies into the receiver’s bandwidth or adapting to different signal polarizations. The innovation lies in the ability to switch an LO's configurations on the fly using technologies like fiber-optic or integrated photonic switches, as well as other methods like optical modulation or tunable delay lines. This dynamic capability allows coherent receivers to switch seamlessly between range-Doppler and Doppler-only modes. As a result, a single system can track both nearby, slow-moving targets and distant, high-velocity objects (up to 20+ km/s) while operating with a compact, low-speed receiver (<1 GHz). This versatility significantly enhances the performance and adaptability of advanced optical sensing and communication systems. While initially developed for NASA’s Navigation Doppler LiDAR project, this invention can support advanced signal detection applications across several industries, including optical communications, aerospace, structural health monitoring, and autonomous vehicles. By enabling real-time reconfiguration, the invention offers improved signal recovery, enhanced sensitivity, and broader system adaptability for challenging detection environments. The technology has gone through prototype development and is currently at TRL 3 (proof-of-concept), and the reconfigured LO is available for patent licensing. Current coherent optical receivers use fixed local oscillators (LOs), and the characteristics of LOs, such as frequency, polarization, or spatial mode, determine which incoming signals can be detected. These constraints reduce sensitivity and restrict the range of detectable signals. Signals that fall outside the receiver’s bandwidth or have mismatched polarization may not be detected. This challenge is especially relevant to NASA’s Navigation Doppler LiDAR, where signals from fast or distant targets can fall outside the receiver’s range or become difficult to detect due to low-frequency noise. To overcome these limitations, researchers at NASA’s Langley Research Center have developed the Reconfigurable Local Oscillator for Coherent Optical Detection. This innovative technology can be applied to LiDAR, fiber-optic sensing, and optical communications. By enabling real-time adjustment of an LO’s properties, the system can dynamically match incoming signal characteristics, enhancing signal recovery, improving sensitivity, and increasing adaptability across a wide range of operating conditions.