Chris Hodges

Herein, the authors investigate the temperature‐dependent properties of delayed luminescence in an as‐grown nitrogen‐containing chemical vapor deposition synthetic diamond gemstone when excited above its bandgap. At room temperature, this gemstone exhibits delayed luminescence from nitrogen‐vacancy centers at 575 nm. However, at 77 K, the first recorded instance of a long‐lived delayed blue luminescence centered at ≈465 nm, accompanied by spectral peaks at 419, 455, and 499 nm is reported. By analyzing spectral and temporal data at different temperatures, it can be speculated on potential photophysical transitions. This discovery documents the initial observation of this delayed luminescence emission, contributing to the collective understanding of synthetic diamonds.

The low-cost thermal infrared ‘THz-Torch’ concept (referred to here as ‘THz-T’) was first introduced over a decade ago, and since then the associated ‘over the THz horizon’ thermal infrared (10-100 THz) implementation technologies have continued to advance. While short range secure wireless communications links have received a great deal of attention, material spectroscopy has only briefly been introduced in a short conference abstract. Here, for the first time, we explore in depth the basic concepts behind THz-T spectroscopy. Moreover, when compared to the unvalidated results within our previous work, we demonstrate an enhanced experimental THz-T spectrometer. A detailed thermal noise power link budget model for both the transmission and reflection modes of operation have been undertaken and independently validated. As a proof of principle, a diverse array of different material types has been …

We present a study of even-parity Rydberg exciton states in cuprous oxide using second harmonic generation (SHG) spectroscopy. Excitonic states with principal quantum number n= 5− 12 were excited by nanosecond pulses around 1143 n m. Using time-resolved single-photon counting, the coherently generated second harmonic was isolated both temporally and spectroscopically from inelastic emission due to lower-lying free and bound excitonic states, which included narrow resonances at 1.993 e V associated with a long lifetime of 641±7 μ s. The near transform-limited excitation bandwidth enabled high-resolution measurements of the exciton lineshape and position, from which we obtained values for the quantum defects of the S and D excitonic states associated with the appropriate crystal symmetries. Odd-parity P and F excitonic states were also observed, in accordance with predicted quadrupole-allowed …

We report exciton-mediated coupling between microwave and optical fields in cuprous oxide (Cu 2 O) at low temperatures. Rydberg excitonic states with principal quantum number up to n= 12 were observed at 4 K using both one-photon (absorption) and two-photon (second harmonic generation) spectroscopy. Near resonance with an excitonic state, the addition of a microwave field significantly changed the absorption line shape, and added sidebands at the microwave frequency to the coherent second harmonic. Both effects showed a complex dependence on n and angular momentum l. All of these features are in semiquantitative agreement with a model based on intraband electric dipole transitions between Rydberg exciton states. With a simple microwave antenna we already reach a regime where the microwave coupling (Rabi frequency) is comparable to the nonradiatively broadened linewidth of the …

High-lying Rydberg states of Mott-Wannier excitons are receiving considerable interest due to the possibility of adding long-range interactions to the physics of excitons. Here, we study Rydberg excitation in bulk synthetic cuprous oxide grown by the optical float zone technique and compare the result with natural samples. X-ray characterization confirms both materials are mostly single crystal, and midinfrared transmission spectroscopy revealed little difference between synthetic and natural material. The synthetic samples show principal quantum numbers up to n= 10, exhibit additional absorption lines, plus enhanced spatial broadening and spatial inhomogeneity. Room temperature and cryogenic photoluminescence measurements reveal a significant quantity of copper vacancies in the synthetic material. These measurements provide a route towards achieving high-n excitons in synthetic crystals, opening a route …