arXiv subjects

David J. Spence

Publications and source records attributed to David J. Spence.

3 recordsLinked to original sources

arXiv2026

Extreme Linewidth Narrowing in Diamond Raman Lasers Enables the Generation of 35 W at 589 nm with Hz-Scale Intrinsic Linewidth

High-power lasers with narrow linewidth and high beam quality in the visible spectrum are essential for emerging quantum and space technologies. Here we report significant advances in diamond Raman lasers, generating diffraction-limited yellow light at 589 nm with output power up to 35 W and enhanced single-frequency stability. The optical-to-optical efficiency from the pump reaches 47.7%, representing a record efficiency for this class of devices. More importantly, the extreme linewidth-narrowing of Raman lasing in diamond enables a reduction in frequency noise exceeding six orders of magnitude, resulting in a measurement-limited intrinsic linewidth of 6 Hz at the maximum power. The laser is further stabilized to the sodium D2a saturation-absorption transition, making it well-suited for sodium-based space and quantum experiments. These results represent a major step toward continuous-wave, high-power, single-frequency laser sources across the visible spectrum that combine ultranarrow linewidth, high efficiency, and near-diffraction-limited beam quality for advanced quantum and space applications.

physics.optics↗

arXiv2021

Absorptive laser threshold magnetometry: combining visible diamond Raman lasers and nitrogen-vacancy centres

We propose a high-sensitivity magnetometry scheme based on a diamond Raman laser with visible pump absorption by an ensemble of coherently microwave driven negatively charged nitrogen-vacancy centres (NV) in the same diamond crystal. The NV centres' absorption and emission are spin-dependent. We show how the varying absorption of the NV centres changes the Raman laser output. A shift in the diamond Raman laser threshold and output occurs with the external magnetic-field and microwave driving. We develop a theoretical framework including steady-state solutions to describe the effects of coherently driven NV centres in a diamond Raman laser. We discuss that such a laser working at the threshold can be employed for magnetic-field sensing. In contrast to previous studies on NV magnetometry with visible laser absorption, the laser threshold magnetometry method is expected to have low technical noise, due to low background light in the measurement signal. For magnetic-field sensing, we project a shot-noise limited DC sensitivity of a few $\mathrm{pT}/\sqrt{\mathrm{Hz}}$ in a well-calibrated cavity with realistic parameters. This sensor employs the broad visible absorption of NV centres and unlike previous laser threshold magnetometry proposals it does not rely on active NV centre lasing or an infrared laser medium at the specific wavelength of the NV centre's infrared absorption line.

quant-ph↗

arXiv2018

Diamond Brillouin Lasers

The coherent interaction between optical and acoustic waves via stimulated Brillouin scattering (SBS) is a fundamental tool for manipulating light at GHz frequencies. Its narrowband and noise-suppressing characteristics have recently enabled microwave-photonic functionality in integrated devices based on chalcogenide glasses, silica and silicon. Diamond possesses much higher acoustic and bandgap frequencies and superior thermal properties, promising increased frequency, bandwidth and power; however, fabrication of low-loss optical and acoustic guidance structures with the resonances matched to the Brillouin shift is currently challenging. Here we use intense cavity-enhanced Raman generation to drive a diamond Brillouin laser without acoustic guidance. Our versatile configuration - the first demonstration of a free-space Brillouin laser - provides tens-of-watts of continuous Brillouin laser output on a 71 GHz Stokes shift with user switching between single Stokes and Brillouin frequency comb output. These results open the door to high-power, high-coherence lasers and Brillouin frequency combs, and are a major step towards on-chip diamond SBS devices.

physics.optics↗