arXiv subjects

Nicholas J. Sorensen

Publications and source records attributed to Nicholas J. Sorensen.

7 recordsLinked to original sources

arXiv2026

Saturable absorption in defect-rich diamond nanophotonics

Diamond is a leading quantum photonics platform due to its ability to host qubits based on crystal defects such as nitrogen-vacancy centres. Fabricating nanophotonic devices from defect-rich diamond, which underpins many quantum sensing technologies, promises enhanced performance and integrability of diamond quantum sensors. Here we demonstrate microdisk cavities fabricated from defect-rich diamond that support optical modes with high quality factor (${Q}\sim7\times10^4$ at $1042\,$nm) and show that they exhibit saturable absorption. Power-dependent spectroscopy measurements spanning 979$\,$nm to 1604$\,$nm are used to observe intensity-dependent cavity loss and extract wavelength-dependent absorption coefficients and saturation intensities. At 1047$\,$nm, we observe saturation and measure a saturation intensity of $2.1\,(8)\,$MW/cm$^2$ and an absorption coefficient of $0.53\,(2)\,$cm$^{-1}$. These results provide insight into defect-mediated optical loss in diamond nanophotonics and suggest strategies to harness defect-induced nonlinearities in future diamond photonic devices.

physics.optics↗

arXiv2026

Photorefractive tuning seeded by third-harmonic light in a diamond photonic crystal cavity

Single-crystal diamond nanocavities have tremendous potential for use in quantum and nonlinear optical technologies. The ability to precisely control their resonant frequencies is essential for many applications, and $\textit{in situ}$ tuning is particularly desirable. In this work, we demonstrate deterministic resonance tuning of a diamond nanocavity. We observed a photorefractive effect in concert with the generation of third-harmonic light within the device. This effect blue-shifted the cavity resonance frequency by $20.2\,(2)\,\text{GHz}$, exceeding the cavity linewidth. The shift corresponded to a fractional change in refractive index of $-1.05\,(1)\times10^{-4}$, and its relaxation occurred over several tens of hours. Although photorefraction is a second-order nonlinear effect and has previously not been observed in diamond owing to its vanishing $χ^{(2)}$, the observed behaviour is consistent with the generation of non-zero $χ^{(2)}$ by electric fields from charged crystal defects. In addition to allowing tuning of diamond cavities for resonant nonlinear and quantum photonics applications, this observation could enable the realisation of diamond frequency converters and electro-optical modulators that rely on second-order nonlinearity.

physics.optics↗

arXiv2025

Nanophotonic magnetometry in a spin-dense diamond cavity

Quantum sensors based on the nitrogen-vacancy (NV) center in diamond are leading platforms for high-sensitivity magnetometry with nanometer-scale resolution. State-of-the-art implementations, however, typically rely on bulky free-space optics or sacrifice spatial resolution to achieve high sensitivities. Here, we realize an integrated platform that overcomes this trade-off by fabricating monolithic whispering-gallery-mode cavities from a diamond chip containing a high density of NV centers and by evanescently coupling excitation to and photoluminescence from the cavity using a tapered optical fiber. Employing a lock-in-amplified Ramsey magnetometry scheme, we achieve a photon-shot-noise-limited DC sensitivity of $58\,\text{nT}/\sqrt{\text{Hz}}$ -- the best sensitivity reported to date for a nanofabricated cavity-based magnetometer. The microscopic cavity size enables sub-micrometer-scale spatial resolution and low-power operation, while fiber-coupling provides a path to scalable on-chip integration. Arrays of such sensors could enable NV-NMR spectroscopy of sub-nanoliter samples, new magnetic-gradient imaging architectures, and compact biosensing platforms.

physics.optics↗

arXiv2025

A simple model for entangled photon generation in resonant structures

The ability to engineer pairs of entangled photons is essential to quantum information science, and generating these states using spontaneous parametric down-conversion (SPDC) in nano- and micrometer-scale materials offers numerous advantages. To properly engineer such sources, a reliable model describing nano- and micrometer-scale SPDC is necessary; however, such a theoretical description remains a challenge. Here, we propose and derive a simplified model to describe SPDC in resonant structures, which considers the generation of photon pairs and the resonant enhancement of spectral bands to be separate processes, even though they actually occur simultaneously. We compare our simplified model to both the rigorous theory of SPDC in an etalon - a simple example of a resonant structure - and our experiments on SPDC in etalons and find agreement for low-gain SPDC. By simplifying the calculations required to generate photon pairs, our model promises to make designing complex resonant structures easier, and it promises to hasten the iteration of designs across the field of quantum state engineering.

quant-ph↗

arXiv2024

Open-Source CubeSat Solar Panels: Design, Assembly, Testing, and On-Orbit Demonstration

Cube satellites, or CubeSats, are small satellites commonly used to perform Earth imaging and on-orbit scientific experiments. CubeSats are often powered using expensive, inflexible commercial-off-the-shelf solar panels, largely due to a lack of flight-qualified open-source alternatives. Here, we describe the design of customizable, deployable solar panels, offering an open-source, cost-effective alternative. Towards a fully open-source CubeSat, our designs have mission-tailored power generation capabilities and simple electrical and mechanical integration. The solar panel designs were demonstrated on-orbit on three satellites in the Northern SPIRIT constellation and will be on AlbertaSat's Ex-Alta~3 satellite, which will launch in 2025. The design files, assembly procedures, and best practices will be open-source-published online. This work lowers the barrier of entry into space, making satellite design easier and less expensive -- students helping students design better satellites.

physics.ins-det↗

arXiv2023

Large-scale optical compression of free-space using an experimental three-lens spaceplate

Recently introduced, spaceplates achieve the propagation of light for a distance greater than their thickness. In this way, they compress optical space, reducing the required distance between optical elements in an imaging system. Here we introduce a spaceplate based on conventional optics in a 4-$f$ arrangement, mimicking the transfer function of free-space in a thinner system - we term this device a three-lens spaceplate. It is broadband, polarization-independent, and can be used for meter-scale space compression. We experimentally measure compression ratios up to 15.6, replacing up to 4.4 meters of free-space, three orders of magnitude greater than current optical spaceplates. We demonstrate that three-lens spaceplates reduce the length of a full-color imaging system, albeit with reductions in resolution and contrast. We present theoretical limits on the numerical aperture and the compression ratio. Our design presents a simple, accessible, cost-effective method for optically compressing large amounts of space.

physics.optics↗

arXiv2021

Efficiency-optimized design of PCB-integrated magnetorquers for CubeSats

CubeSats are miniature satellites used to carry experimental payloads into orbit, where it is often critical to precisely control their attitude. One way to do this is through the use of magnetorquers, which can be integrated into PCBs. This technique saves considerable space and capital when compared with more common torque-rod magnetorquer systems. Here we derive a method of analyzing different PCB-integrated magnetorquer geometries, parametrizing them such that the magnetic moment and efficiency are optimized. Furthermore, by modulating the trace width, the trace number, and other electrical characteristics of the magnetorquer coil, this paper optimizes the generated magnetic moment. Both constant voltage and constant current sources are analyzed as inputs. These optimizations are then simulated in COMSOL for multiple geometries, and it is found that there exists an optimal geometry, given a specified power dissipation. Simulations verify the general trend and maxima of these derivations, barring small, consistent re-scaling in the magnitude of the coil resistance. It is also found that these PCB-integrated magnetorquers provide a sufficient alternative to commercial coil magnetorquers - particularly in volume-restricted configurations. This study extends such analysis to larger CubeSat configurations, and finds that these larger implementations increase magnetorquer efficiency. Optimizations for common PCB-implementable geometries on small satellites are tabulated in the Appendix.

physics.app-ph↗