Signal amplification and control in optical cavities with off-axis feedback

TL;DR

This paper explores how off-axis feedback in optical cavities enables precise control and amplification of weak signals, allowing independent tuning of phase and velocity, and enabling non-mechanical steering and splitting of light signals.

Contribution

It introduces a novel approach using off-axis feedback to control signal amplification, phase, and velocity in optical cavities, expanding capabilities for optical signal manipulation.

Findings

Weak signals can be strongly amplified with low background noise.

Transverse phase and group velocities can be independently tuned.

Signals can be steered and split without mechanical movement.

Abstract

We consider a large class of optical cavities and gain media with an off-axis external feedback which introduces a two-point nonlocality. This nonlocality moves the lasing threshold and opens large windows of control parameters where weak light spots can be strongly amplified while the background radiation remains very low. Furthermore, transverse phase and group velocities of a signal can be independently tuned and this enables to steer it non mechanically, to control its spatial chirping and to split it into two counter-propagating ones.