# Second-harmonic enhanced feedforward intensity noise eater

## TL;DR

This paper demonstrates that incorporating second harmonic generation into an electro-optic feedforward intensity noise eater enhances its noise reduction capabilities, even at low conversion efficiencies, by applying quantum nondemolition theory.

## Contribution

It introduces a novel design replacing the beamsplitter with second harmonic generation and a dichroic mirror to improve noise suppression in intensity noise eaters.

## Key findings

- Enhanced noise reduction performance with second harmonic generation.
- Effective even at low conversion efficiencies.
- Application of quantum nondemolition theory to real-world devices.

## Abstract

Quantum nondemolition theory has been well understood for a number of decades, however, applications of such techniques remain limited owing to the increased complexity that these techniques require. In this paper, quantum nondemolition theory is used to investigate the performance of a real world device, an electro-optic feed-forward intensity noise eater. It is shown that by replacing the typical beamsplitter in such a device with a single pass second harmonic generation followed by a dichroic mirror the performance of the noise eater can be significantly improved, even with low conversion efficiencies.