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Optomechanical Inertial Sensors and Feedback Cooling


Blasius, Timothy Dobson (2016) Optomechanical Inertial Sensors and Feedback Cooling. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9NK3BZS.


The optomechanical interaction is an extremely powerful tool with which to measure mechanical motion. The displacement resolution of chip-scale optomechanical systems has been measured on the order of 1⁄10th of a proton radius. So strong is this optomechanical interaction that it has recently been used to remove almost all thermal noise from a mechanical resonator and observe its quantum ground-state of motion starting from cryogenic temperatures.

In this work, chapter 1 describes the basic physics of the canonical optomechanical system, optical measurement techniques, and how the optomechanical interaction affects the coupled mechanical resonator. In chapter 2, we describe our techniques for realizing this canonical optomechanical system in a chip-scale form factor.

In chapter 3, we describe an experiment where we used radiation pressure feedback to cool a mesoscopic mechanical resonator near its quantum ground-state from room-temperature. We cooled the resonator from a room temperature phonon occupation of <n> = 6.5 million to an occupation of <n> = 66, which means the resonator is in its ground state approximately 2% of the time, while being coupled to a room-temperature thermal environment. At the time of this work, this is the closest a mesoscopic mechanical resonator has been to its ground-state of motion at room temperature, and this work begins to open the door to room-temperature quantum control of mechanical objects.

Chapter 4 begins with the realization that the displacement resolutions achieved by optomechanical systems can surpass those of conventional MEMS sensors by an order of magnitude or more. This provides the motivation to develop and calibrate an optomechanical accelerometer with a resolution of approximately 10 micro-g/rt-Hz over a bandwidth of approximately 30 kHz. In chapter 5, we improve upon the performance and practicality of this sensor by greatly increasing the test mass size, investigating and reducing low-frequency noise, and incorporating more robust optical coupling techniques and capacitive wavelength tuning. Finally, in chapter 6 we present our progress towards developing another optomechanical inertial sensor - a gyroscope.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:optics, photonics, qunatum optics, inertial sensors
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Painter, Oskar J.
Group:Institute for Quantum Information and Matter, Kavli Nanoscience Institute
Thesis Committee:
  • Painter, Oskar J. (chair)
  • Vahala, Kerry J.
  • Faraon, Andrei
  • Adhikari, Rana
Defense Date:12 January 2016
Non-Caltech Author Email:tdblasiu (AT)
Record Number:CaltechTHESIS:01122016-170853872
Persistent URL:
Related URLs:
URLURL TypeDescription Optical read out and feedback cooling of a nanostring optomechanical cavity A high-resolution microchip optomechanical accelerometer A chip-scale integrated cavity-electro-optomechanics platform
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9532
Deposited By: Timothy Blasius
Deposited On:22 Jan 2016 23:40
Last Modified:02 Jun 2020 21:48

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