Differential phase-diversity electrooptic modulator for cancellation of fiber dispersion and laser noise

Abstract

Bandwidth and noise are fundamental considerations in all communication and signal processing systems. The group-velocity dispersion of optical fibers creates nulls in their frequency response, limiting the bandwidth and hence the temporal response of communication and signal processing systems. Intensity noise is often the dominant optical noise source for semiconductor lasers in data communication. In this paper, we propose and demonstrate a class of electrooptic modulators that is capable of mitigating both of these problems. The modulator, fabricated in thin-film lithium niobate, simultaneously achieves phase diversity and differential operations. The former compensates for the fiber’s dispersion penalty, while the latter overcomes intensity noise and other common mode fluctuations. Applications of the so-called four-phase electrooptic modulator in time-stretch data acquisition and in optical communication are demonstrated.

Exploring Wavefront Detection in Imaging Systems with Rectangular Apertures Using Phase Diversity

“…Based on this, Gonsalves introduced the phase diversity algorithm [ 14 ], which recovers the distorted phase information using an objective function that incorporates images from different defocus planes. Since then, the PD method has undergone comprehensive research by institutions such as the University of Central Florida [ 15 ], Lockheed Martin Space Systems [ 16 , 17 ], and the Chinese Academy of Sciences [ 18 , 19 , 20 ], affirming its practicality. This method has already found application in adjusting ground-based telescopes and co-phase detection for segmented mirror telescopes.…”