Synopsis

Gravitational wave detectors have reached the thermodynamic limit of optical coating performance and require novel coating materials and noise mitigation techniques for further sensitivity improvements. This project is to implement a phase tracking system for the optical beat between two 2µm-band lasers for coating thermal noise measurements.

Research fields

Photonics, Lasers and Nonlinear Optics

Required background

A working knowledge and laboratory experience with optics and lasers is strongly recommended. Computational and programming skills (e.g. Python, MATLAB, Finite Element Analysis, FPGAs) are preferred. The project scope can be adjusted according to student level and involve a flexible amount of optics, electronics, and programming work.

Description

Gravitational wave detectors are in many ways the most sensitive instruments ever built and have opened a new window to the universe. The steadily growing number of discoveries helps us develop a better understanding of our cosmic setting and probe for exciting new fundamental physics.

Gravitational wave detection has reached the thermal noise limit of optical coating technology: Thermal effects in the mirror coatings drown potential signals in noise. This has sparked a broad search for novel coating materials, coating topologies, and mitigating technologies. One of the most promising avenues towards future gravitational wave detectors is the use of cryogenically cooled silicon mirrors and 2µm wavelength lasers.

Your goal in this project is to design a tracking system for the differential phase noise between two 2µm-band lasers. The measurement is to be performed between two orthogonal spatial modes of laser light – requiring a way to first break orthogonality while sacrificing as little light optical power as possible. Depending on the laser noise characteristics, this measurement needs to be viable at frequencies ranging from a few 10s of MHz up to several GHz. The high bandwidth phase tracking and will be implemented in programmable digital hardware with FPGAs.

The Centre for Gravitational Astrophysics offers a collaborative, diverse, and supportive research environment across the full breadth of gravitational wave discovery. The Centre is a joint effort of RSAA and RSPhys, and hosts a node of the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav).