Undergraduate Honors Theses

Thesis Defended

Spring 2017

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Physics

First Advisor

Prof. Cindy Regal

Abstract

In the new field of Cavity Optomechanics the modes of a mechanical oscillator are strongly coupled to the resonant modes of a cavity, which enables the use of optical techniques, such as laser cooling, to manipulate and study oscillators. Oscillators with small mechanical dissipation, when interacting with low-loss, intense cavity field, can be cooled down to their harmonic ground state, a true breakthrough allowing for the study of the intrinsic quantum behavior of macroscopic objects. It is of interest, therefore, to use and develop mechanical oscillators with very small loss, or, in other words, very small coupling with the thermal bath and environment. One of the best materials in this sense, Si3N4, has been used in many optomechanical experiments due to their large quality factors, low optical absorption, and high mode frequencies. Nonetheless, modifications of membrane Si3}N4 such as trampolines and phononic crystals (PnC) have shown significant improvement of in their quality factor. This thesis describes new Si3N4 resonator designs, the flower and the web, that uses both the trampoline and PnC characteristics in order to provide even higher quality factors and frequencies. By enabling better resonators, the new designs are also very suitable in extreme force sensing applications. Moreover, besides discussing how to attenuate mechanical losses, this thesis also contains heating models for Si3N4, which corroborate the extremely low optical absorption essential to the most ambitious cavity optomechanics experiments.

Available for download on Sunday, April 14, 2019

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