Characterizing the Nonlinear Optical Response of Silicon Vacancy Centers in Diamond and Showcasing the Next Generation of Optical Frequency Combs

Abstract

In the first half of this work, we employ multidimensional coherent spectroscopy (MDCS) to show that a previously unknown hidden population of dark silicon-vacancy centers dominates the resonant nonlinear optical response of an ensemble of such centers. We present evidence to support our assertion that this phenomenon is due to strain-induced coupling to a dark state. We posit two mechanisms by which this could occur.

Furthermore, we use a particular version of MDCS sensitive only to excitation dependent interactions between color centers, known as double-quantum spectroscopy, to show that inter-center interactions (causing peak shifts on the order of between 4 and 40 GHz) occur in our sample and are likely electronic dipole-dipole interactions. We demonstrate rudimentary control over the interaction strength between color center pairs by introducing an intense optical pulse and varying the pulse strength. As a function of the pulse field, the double quantum spectra show pairwise Rabi-like oscillations in the peak amplitude, which is a direct signature of varying interaction strength.

In the latter half of this thesis, we showcase a new breed of semiconductor diode-based miniaturized frequency combs. Two dozen of our combs fit within a grain of rice. In this thesis, we characterize the modelocking physics of these frequency combs. We show that these lasers output coherent frequency modulated frequency combs, providing evidence that passive modelocking within the laser cavity occurs to stabilize the comb output.

Beyond demonstrating that these frequency combs are indeed coherent, we also demonstrate their use in a practical dual-comb spectroscopy application. We acquire a dual-comb absorption spectrum of a gas cell, with a resolution better than 25 GHz achieved in only 10 µs of data acquisition time. We also show that these frequency combs can be battery powered, and that they are efficient, tunable, and simple. This thesis shows that diode frequency combs are truly portable and capable of providing a platform for practical precision measurement to thrive.