All-optical sampling and magnification based on XPM-induced focusing

TL;DR

This paper presents a novel all-optical technique for noiseless sampling and magnification of signals using cross-phase modulation in optical fibers, eliminating the need for active gain media and high-power pumps.

Contribution

It introduces a new method leveraging XPM-induced focusing for simultaneous signal sampling and magnification without active gain or high-power pumps.

Findings

Achieved 40-GHz sampling rate.

Demonstrated 8-dB magnification of nanosecond signals.

Experimental results match theoretical predictions.

Abstract

We theoretically and experimentally investigate the design of an all-optical noiseless magnification and sampling function free from any active gain medium and associated high-power continuous wave pump source. The proposed technique is based on the co-propagation of an arbitrary shaped signal together with an orthogonally polarized intense fast sinusoidal beating within a normally dispersive optical fiber. Basically, the strong nonlinear phase shift induced by the sinusoidal pump beam on the orthogonal weak signal through cross-phase modulation turns the defocusing regime into localized temporal focusing effects. This periodic focusing is then responsible for the generation of a high-repetition-rate temporal comb upon the incident signal whose amplitude is directly proportional to its initial shape. This internal redistribution of energy leads to a simultaneous sampling and magnification of the signal intensity profile. This process allows us to experimentally demonstrate a 40-GHz sampling operation as well as an 8-dB magnification of an arbitrary shaped nanosecond signal around 1550 nm in a 5-km long normally dispersive fiber. The experimental observations are in quantitative agreement with numerical and theoretical analysis.