Exploiting spacetime symmetry in dissipative nonlinear multimode amplifiers for output control

TL;DR

This paper introduces a novel spacetime symmetry in dissipative nonlinear multimode fiber amplifiers that enables output control through phase conjugation and gain/absorption substitution, despite energy dissipation breaking traditional time-reversal symmetry.

Contribution

The authors identify a new spacetime symmetry in dissipative nonlinear systems that allows for output control without relying on time-reversal symmetry.

Findings

Spacetime symmetry maps target output to input in saturated multimode fiber amplifiers.

Phase conjugation and gain/absorption substitution enable output control.

The symmetry holds in steady-state and for slowly varying inputs.

Abstract

Time-reversal symmetry enables shaping input waves to control output waves in many linear and nonlinear systems; however energy dissipation violates such symmetry. We consider a saturated multimode fiber amplifier in which light generates heat flow and suffers nonlinear thermo-optical scattering, breaking time-reversal symmetry. We identify a spacetime symmetry which maps the target output back to an input field. This mapping employs phase conjugation, gain and absorption substitution but not time reversal, and holds in steady-state and for slowly varying inputs. Our results open the possibility of output control of a saturated multimode fiber amplifier.