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Engineering room-temperature quantum magnetic sensors with fibre-cavity diamond lasers

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posted on 2023-01-24, 06:06 authored by Sarath Raman Nair

This thesis studies the engineering of quantum magnetic sensors based on diamond lasers containing NV- colour centres. Specifically, the thesis experimentally and theoretically investigates two different scenarios for realizing diamond lasers in mechanically tunable fibre-based Fabry-Perot cavities. 

In the first scenario, we experimentally explore a diamond-loaded open tunable fibercavity system as a contender for realizing lasing with the negatively charged nitrogen-vacancy (NV-) centre in diamond as the gain medium. We measure the transmission characteristics of a cavity-resonant laser beam at a wavelength of 721 nm, close to the maximum of emission of the NV- phonon sideband, both with and without a green pump laser at 532 nm. For moderate green pump powers, we observe an amplification of the resonant red laser light and at the same time a reduction of the spontaneously emitted background photons. When increasing the pump power further, the amplification saturates and at the same time we see an increase in spontaneous photon emission. A qualitative model including stimulated emission and charge state switching of the NV- centre captures the dynamics in the experiment very well. The results allow conclusions to be drawn about the material challenges of realizing an NV- laser in diamond. 

In the second scenario, we theoretically study Raman lasing from a diamond crystal containing NV- centres. The intra-cavity absorption by the NV- centres modifies the Raman laser, and two interesting regimes are identified based on the position of the Raman and pump laser wavelengths with respect to the zero-phonon line (637nm) of the NV- centre. When both the pump and Raman wavelengths are below the zero-phonon line we identify a magnetically tunable bistability. When only the pump wavelength is below the zero-phonon line, we predict a shift in the laser threshold dependent on the NV- spin centres. Furthermore, we propose that such a system can be used as a technically demanding magnetic field sensor with a predicted DC sensitivity of the order of pT/flz. 


Table of Contents

1 Introduction -- 2 Quantum magnetometry with NV- centres -- 3 Magnetometry with a fibre cavity NV- laser and charge state switching of NV- centres -- 4 Realization of laser amplifier due to stimulated emission of NV centres in fibre cavities -- 5 Room-temperature quantum sensor with diamond Raman lasers combined with MW driven NV- centres -- 6 Conclusions and outlook -- References


A thesis submitted to Macquarie University for the degree of Doctor of Philosophy

Awarding Institution

Macquarie University

Degree Type

Thesis PhD


Thesis (PhD), Macquarie University, Department of Physics and Astronomy, 2020

Department, Centre or School

Department of Physics and Astronomy

Year of Award


Principal Supervisor

Thomas Volz

Additional Supervisor 1

Lachlan Rogers


Copyright: The Author Copyright disclaimer:




111 pages

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