Technique for precision optical timing measurements

摘要

Abstract: High-accuracy absolute timing of optical pulses is usually performed by PMTs, in conjunction with advanced discriminator and time-measurement electronics. This paper presents a new technique that is capable of less than 1.0 psec absolute timing measurements, using Si APDs, with significantly relaxed requirements for the discriminator and timing electronics. An EO modulator is used to modulate the polarization of the optical pulse at a microwave frequency (e.g., 8 GHz), and the two resulting polarization components are detected by the APDs. Relative signal levels at the two polarizations provide a vernier timing measurement with respect to the phase of the microwave modulating signal, and the time ambiguity is resolved by a relatively coarse timing measurement of the detected signals. This technique offers the potential for simpler, lower-cost implementations than PMT and/or streak camera systems, and it is applicable to a wider range of wavelengths, particularly near-IR systems. This paper discusses the general principles and design issues of the technique, and describes a particular design implementation applicable to 2-color lidar ranging. !2