Optical Springs and Optomechan Interactions
One of the recent developments is to use optomechanical systems to create a “white light cavity” to broaden the gravitational wave detector sensitivity. To achieve a practical white light cavity, a very low-loss system is required. Novel optomechanical systems are being developed to test the strength of the optomechanical interaction between the laser radiation pressure and the mechanical resonators. There are several sub-projects related to this topic: Bulk Acoustic Wave (BAW) resonator cavity, Phononic Crystal resonator cavity and Phononic Crystal resonator cavity.
Bulk Acoustic Wave (BAW) resonator cavity
BAW resonators were shown to have a very low mechanical loss. This project is focused on investigating the optomechanical interaction strength of an optical cavity with a quartz BAW resonator
Phononic Crystal resonator cavity
Phononic Crystal is a metamaterial where the engineering periodic structure results in band gaps that certain frequency energy cannot propagate. This project will be focused on using a 2D phononic crystal Silicon Nitride (Si3N4) membrane as a cavity resonator to explore the optomechanical interactions.
Optical Parametric Amplifier
The Optical Parametric Amplifier (OPA) is widely used for generating squeezed vacuum state to be injected into the gravitational wave detector for improving the quantum noise limited sensitivity. In this project, we will integrate the OPA with an optomechanical cavity to enhance the optomechanical coupling strength while squeezing the noise simultaneously. The device has the potential to enable the GW detector to break the sensitivity barrier of the standard quantum limit.
The microresonator mirror cavity
These optomechanical systems use microresonator mirrors made from a few layers of crystalline optical coating. Using the optical dilution effect, these optomechanical systems can achieve very low loss.
High Precision Rotational Sensor
Gravitational wave detectors require a high level of vibration isolation and control. Coupling between the ground tilt and horizontal displacement will greatly hinder the effectiveness of the control system and thus limit the sensitivity of the detector. This project will involve testing the performance of a pure low-frequency rotation sensor that incorporates many innovative designs and concepts, including the laser walk-off sensor, Isoelastic internal mass/flexure, and tunable anti-spring, to name a few. This device will not only be used for gravitational wave detectors and will also have wider applications in seismology.
Matrix Heater for thermal correction of gravitational wave detector mirror aberration
Mirrors in gravitational wave detectors are distorted by the enourmous optical power contained in the cavity heating and thermally distorting the mirror. The mirror distortions are corrected by heating the mirror with an ‘opposite’ heating pattern. We are devloping a mattrix heater that can project an arbritrary heating mattern on the mirror. In this project you will build a prototype matrix heater and test it with thermal cameras and project the heating pattern onto a suspended mirror at the Gingin High Optical Power Facility.
Parametric Instability and Control
Gravitational wave detectors have very high laser power (MW) inside the optical cavities to reduce shot noise. The radiation pressure force of the optical power will excite the mirrors’ mechanical modes under certain interaction conditions, causing the mirror motion to increase exponentially. This process is called parametric instability and will result in the cavity losing lock and interrupting the operation of the gravitational wave detectors.
This project will investigate various methods to mitigate and control parametric instabilities, including thermal tuning, optical feedback, acoustic damper design and interferometer configureation design and simulation.
Novel arm length stabilization system for next generation GW detectors
Gravitational wave detector test masses must be controlled from their free-swinging states. This is accomplished using the Arm Length Stabilization (ALS) system, which pre-stabilizes the arm cavity length with an auxiliary laser phase-locked to the science laser. However, next-generation gravitational wave detectors will use lasers of different wavelengths and coatings, rendering the current ALS system ineffective.
This project focuses on the design and development of a novel ALS system that will be compatible with the upgraded detectors. It offers a unique opportunity to contribute to cutting-edge gravitational wave research.
Investigate Birefringence in Silicon Test Mass
Silicon is a potential test mass material for the 3rd generation GW detectors, due to its high thermal conductivity, low thermal expansion at cryogenic temperatures, and high mechanical quality factor.
The project …
Silicon Test Mass & Optical Coating Mechanical Properties
It is desirable to have very low mechanical loss in both the test mass substrates and the optical coatings. Crystaline coating showed promising properties. This project is to investigate the mechanical loss in silicon test masses and the effect of the loss due to the optical coatings.