Chirped Lidar Using Simplified Homodyne Detection

A simplified homodyne detection scheme for linear FM modulated lidar is presented in which pulse dechirping is performed in the optical domain. This method provides quantum limited detection sensitivity with much less receiver complexity compared to heterodyne detection systems. Another advantage of this approach is the reduced bandwidth requirement for the photodetector. This removes the limit on the chirp bandwidth, and enables the use of more efficient photodiodes with larger detector area. A field trial using a 5-in aperture diameter commercial telescope and a 370-m target range verified the sensitivity estimation and demonstrated the feasibility of this technique.