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Updated: Jul 17, 2026

Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Nonreciprocity of counterpropagating signals in a monolithically integrated Sagnac interferometer
Venon M Menon1, Wilson Tong, Fengnian Xia
1Center for Photonics and Optoelectronic Materials, Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Abstract:
We demonstrate nonlinearly induced nonreciprocity of counterpropagating waves in a monolithically integrated Sagnac interferometer that employs a semiconductor optical amplifier as the nonlinear element. We show that the dependence of the linewidth enhancement factor on charge injection can influence the third-order nonlinearity in the semiconductor gain medium to a surprisingly large degree. This effect is utilized to control the phases of the counterpropagating signals in the interferometer. A theoretical model is used to explain the experimental observations. We show that these effects have significant practical implications by demonstrating an all-optical controlled-NOT gate.
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