Optical Square Waves in a Kerr-Nonlinear Resonator with Two Delayed Feedback Loops

Abstract

This paper presents a theoretical study of the dynamics of an optical field in a cavity with Kerr nonlinearity, external signal injection, and two delayed optical feedback loops. The mathematical model is formulated as a delay-differential equation that accounts for the following effects: self-phase modulation arising from the Kerr nonlinearity; field decay inside the cavity due to mirror losses; a linear phase shift caused by the detuning between the cavity’s longitudinal resonance frequency and the frequency of the injected radiation; external injection of coherent radiation; and two optical feedback loops described in the standard Lang–Kobayashi form.
It is shown that square-wave optical signals can be sustained in the system when the delay times of the two feedback loops are in an integer ratio. These waveforms consist of a periodic alternation between two or more nearly constant-intensity plateaus separated by sharp transitions. The number of plateaus is determined by the model parameters, including the injection strength, detuning, and feedback strengths. Parameter regions are identified in which square-wave optical signals with two, three, or more intensity plateaus are formed. The results may be useful for designing novel systems for information processing and transmission, including optical neural networks, as well as for metrological applications.

Speaker

Anton Krents
Samara University
Russia

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