Experimental demonstration of a dual-frequency laser free from anti-phase noise

TL;DR

This paper demonstrates a dual-frequency solid-state laser with over 20 dB reduction in anti-phase noise, achieved by aligning orthogonal polarization modes with the crystal axes, without feedback loops.

Contribution

It presents the first experimental realization of a low-noise dual-frequency laser using polarization and crystal orientation to suppress anti-phase noise.

Findings

Over 20 dB noise reduction at anti-phase relaxation oscillation frequency.

Anti-phase noise increases when deviating from the optimal polarization alignment.

The nonlinear coupling constant plays a key role in noise suppression.

Abstract

A reduction of more than 20 dB of the intensity noise at the anti-phase relaxation oscillation frequency is experimentally demonstrated in a two-polarization dual-frequency solid-state laser without any optical or electronic feedback loop. Such a behavior is inherently obtained by aligning the two orthogonally polarized oscillating modes with the crystallographic axes of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The anti-phase noise level is shown to increase as soon as one departs from this peculiar configuration, evidencing the predominant role of the nonlinear coupling constant. This experimental demonstration opens new perspectives on the design and realization of extremely low noise dual-frequency solid-state lasers.