ORCID Profile
0000-0001-8828-6469
Current Organisation
University of Western Australia
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Quantum optics and quantum optomechanics | Photonic and electro-optical devices sensors and systems (excl. communications) | Quantum physics | Astronomical instrumentation |
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2020.39
Abstract: Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2508951
Publisher: Optica Publishing Group
Date: 12-2020
DOI: 10.1364/OSAC.412607
Abstract: Laser beams with orbital angular momentum (OAM) have applications ranging from optical communications to quantum optics. However, the generation of OAM beams, particularly with variable OAM order, remains a challenge. We demonstrate, for the first time, the generation of OAM beams with variable OAM order using an optical phased array (OPA). OPAs are a multi-emitter solid-state device able to manipulate the distribution of optical power in the far field by controlling the relative phase of in idual emitters. By applying an azimuthal phase offset to a hexagonal arrangement of laser emitters, we are able to generate OAM beams and change the OAM order easily and rapidly. This method is scalable to hundreds of emitters and GHz rate phase modulation.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2021
Publisher: Optica Publishing Group
Date: 27-09-2022
DOI: 10.1364/OL.470523
Abstract: Step-index optical fiber preforms are manufactured and drawn into fibers using low-cost consumer-grade fused deposition modeling (FDM) 3D printers with no other specialist tooling. The fibers are fabricated from polyethylene terephthalate glycol (PETG) cladding with an acrylonitrile buatadiene styrene (ABS) core, resulting in V 2.4 after drawing. The fibers are measured to have a loss of α ≈ 0.78 dB/cm, which matches previous polymer fibers manufactured using draw towers. The printing of multimode optical couplers with reliable 50:50 split ratios is also demonstrated. This work points toward the fabrication of useful and bespoke optical devices with low-cost 3D printers.
Publisher: SPIE
Date: 30-12-2019
DOI: 10.1117/12.2539892
Publisher: Springer Science and Business Media LLC
Date: 06-2020
Publisher: Springer Science and Business Media LLC
Date: 31-10-2022
DOI: 10.1038/S41598-022-22027-0
Abstract: Free-space optical communications are poised to alleviate the data-flow bottleneck experienced by spacecraft as traditional radio frequencies reach their practical limit. While enabling orders-of-magnitude gains in data rates, optical signals impose much stricter pointing requirements and are strongly affected by atmospheric turbulence. Coherent detection methods, which capitalize fully on the available degrees of freedom to maximize data capacity, have the added complication of needing to couple the received signal into single-mode fiber. In this paper we present results from a coherent 1550 nm link across turbulent atmosphere between a deployable optical terminal and a drone-mounted retroreflector. Through 10 Hz machine vision optical tracking with nested 200 Hz tip/tilt adaptive optics stabilisation, we corrected for pointing errors and atmospheric turbulence to maintain robust single mode fiber coupling, resulting in an uninterrupted 100 Gbps optical data link while tracking at angular rates of up to 1.5 deg/s, equivalent to that of spacecraft in low earth orbit. With the greater data capacity of coherent communications and compatibility with extant fiber-based technologies being demonstrated across static links, ground-to-low earth orbit links of Terabits per second can ultimately be achieved with capable ground stations.
Publisher: Optica Publishing Group
Date: 04-04-2022
DOI: 10.1364/OL.453869
Abstract: Corner cube retroreflectors are commonly used as cooperative targets in free-space laser applications. The previous literature suggests that due to path reciprocity, a retroreflected beam is self-corrected across a turbulent atmosphere and should show no angle-of-arrival variability in the near field. This is at odds with recent experiments that rely on angle-of-arrival measurements in retroreflected beams for effective tip/tilt correction. In this Letter we investigate the mechanism behind observed angle-of-arrival variability using numerical field propagation to model various transceiver and retroreflector geometries. We determine that asymmetric truncation of a curved wavefront at the retroreflector, transceiver, or both, results in a difference in tip/tilt between the transmitted and reflected wavefronts. This difference propagates as angle-of-arrival variation at the transceiver despite reciprocity, providing the error signal necessary for adaptive optics tip/tilt correction without a remote beacon.
Publisher: Pleiades Publishing Ltd
Date: 04-2017
Publisher: SPIE-Intl Soc Optical Eng
Date: 12-10-2020
Publisher: The Optical Society
Date: 31-07-2013
DOI: 10.1364/OL.38.002893
Publisher: Optica Publishing Group
Date: 30-06-2023
DOI: 10.1364/OL.492356
Abstract: Free-space continuous-wave laser interferometry using folded links has applications in precision measurement for velocimetry, vibrometry, optical communications, and verification of frequency transfer for metrology. However, prompt reflections from the transceiver optics degrade the performance of these systems, especially when the power of the returning signal is equal to or less than the power of the prompt reflections. We demonstrate phase stabilized free-space continuous-wave optical frequency transfer that exploits the auto-correlation properties of pseudo-random binary sequences to filter out prompt reflections. We show that this system significantly improves the stability and robustness of optical frequency transfer over a 750 m turbulent free-space channel, achieving a best fractional frequency stability of 8 × 10 −20 at an integration time of τ = 512 s, and cycle-slip-free periods up to 162 min.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2018
Publisher: SPIE-Intl Soc Optical Eng
Date: 17-02-2022
Publisher: Optica Publishing Group
Date: 22-05-2023
DOI: 10.1364/AO.491440
Abstract: We demonstrate 111.8 Gb/s coherent optical communication throughput over a 10.3 km folded free-space laser range. Folded links are low complexity to establish and provide a high uptime for testing equipment. The communication signals were sourced from an un-modified commercial off-the-shelf transceiver intended for long-haul fiber networks. Wavelength dependence was explored by testing 52 optical C-band channels over the course of an evening. In the future, such high-bandwidth communications will be used in feeder links from satellites in geosynchronous orbit. Optical power measurements of the received signal are compared with atmospheric theory to determine the turbulence strength exhibited and therefore the applicability of the laser range to space-to-ground links. We show that the high-uptime, 10.3 km laser range is suitable for testing high-bandwidth space-to-ground optical communication systems intended for links to geosynchronous orbit at 20°–50° elevation.
Publisher: Optica Publishing Group
Date: 21-04-2023
DOI: 10.1364/OE.483767
Abstract: Geopotential and orthometric height differences between distant points can be measured via timescale comparisons between atomic clocks. Modern optical atomic clocks achieve statistical uncertainties on the order of 10 −18 , allowing height differences of around 1 cm to be measured. Frequency transfer via free-space optical links will be needed for measurements where linking the clocks via optical fiber is not possible, but requires line of sight between the clock locations, which is not always practical due to local terrain or over long distances. We present an active optical terminal, phase stabilization system, and phase compensation processing method robust enough to enable optical frequency transfer via a flying drone, greatly increasing the flexibility of free-space optical clock comparisons. We demonstrate a statistical uncertainty of 2.5×10 −18 after 3 s of integration, corresponding to a height difference of 2.3 cm, suitable for applications in geodesy, geology, and fundamental physics experiments.
Publisher: American Physical Society (APS)
Date: 14-01-2022
Publisher: American Physical Society (APS)
Date: 04-05-2023
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2018.48
Abstract: This paper describes the technical details and practical implementation of the phase synchronisation system selected for use by the Mid-Frequency Square Kilometre Array. Over a four-year period, the system has been tested on metropolitan fibre-optic networks, on long-haul overhead fibre at the South African Square Kilometre Array site, and on existing telescopes in Australia to verify its functional performance. The tests have shown that the system exceeds the 1-s Square Kilometre Array coherence loss requirement by a factor of 2 560, the 60-s coherence loss requirement by a factor of 239, and the 10-min phase drift requirement by almost five orders-of-magnitude. The paper also reports on tests showing that the system can operate within specification over all the required operating conditions, including maximum fibre link distance, temperature range, temperature gradient, relative humidity, wind speed, seismic resilience, electromagnetic compliance, frequency offset, and other operational requirements.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2018
Publisher: Optica Publishing Group
Date: 07-2020
DOI: 10.1364/OL.393007
Abstract: Optical phased arrays (OPAs) are devices that use the coherence of light to control the interference pattern in the far field, which enables them to steer a laser beam with no moving parts. As such, OPAs have potential applications in laser communications, target acquisition and tracking, metrology, and directed energy. In this Letter, we present a control architecture for an actively phase-locked OPA, capable of steering a laser beam at speeds limited by the actuation bandwidth of electro-optic modulators. The system achieved an output phase stability of λ / 770 and steering speeds up to 1 MHz. The digital control architecture can be extended to GHz steering speeds, is readily scalable to hundreds of emitters, and is compatible with high-power arrays.
Publisher: MDPI AG
Date: 26-11-2021
DOI: 10.3390/S21237904
Abstract: Satellite-mediated quantum key distribution (QKD) is set to become a critical technology for quantum-secure communication over long distances. While satellite QKD cannot be effectively eavesdropped, we show it can be disrupted (or ‘jammed’) with relatively simple and readily available equipment. We developed an atmospheric attenuation and satellite optical scattering model to estimate the rate of excess noise photons that can be injected into a satellite QKD channel by an off-axis laser, and calculated the effect this added noise has on the quantum bit error rate. We show that a ground-based laser on the order of 1 kW can significantly disrupt modern satellite QKD systems due to photons scattering off the satellite being detected by the QKD receiver on the ground. This class of laser can be purchased commercially, meaning such a method of disruption could be a serious threat to effectively securing high-value communications via satellite QKD in the future. We also discuss these results in relation to likely future developments in satellite-mediated QKD systems, and countermeasures that can be taken against this, and related methods, of disruption.
Publisher: Optica Publishing Group
Date: 2020
DOI: 10.1364/CLEOPR.2020.P4_20
Abstract: We present results for tracking the phase of a sub-10 fW optical carrier using an optimized phasemeter and cavity-stabilized lasers for future space-based interferometers.
Publisher: Springer Science and Business Media LLC
Date: 22-01-2021
DOI: 10.1038/S41467-020-20591-5
Abstract: Timescale comparison between optical atomic clocks over ground-to-space and terrestrial free-space laser links will have enormous benefits for fundamental and applied sciences. However, atmospheric turbulence creates phase noise and beam wander that degrade the measurement precision. Here we report on phase-stabilized optical frequency transfer over a 265 m horizontal point-to-point free-space link between optical terminals with active tip-tilt mirrors to suppress beam wander, in a compact, human-portable set-up. A phase-stabilized 715 m underground optical fiber link between the two terminals is used to measure the performance of the free-space link. The active optical terminals enable continuous, cycle-slip free, coherent transmission over periods longer than an hour. In this work, we achieve residual instabilities of 2.7 × 10 −6 rad 2 Hz −1 at 1 Hz in phase, and 1.6 × 10 −19 at 40 s of integration in fractional frequency this performance surpasses the best optical atomic clocks, ensuring clock-limited frequency comparison over turbulent free-space links.
Publisher: IEEE
Date: 05-2018
Publisher: The Optical Society
Date: 18-04-2017
DOI: 10.1364/OL.42.001648
Publisher: American Physical Society (APS)
Date: 29-08-2018
Publisher: MDPI AG
Date: 31-01-2023
Abstract: Free-space optical (FSO) communication promises to bring fibre-like speeds to data transmissions between ground, sky and space. This is becoming more important in light of the increasing volume of data collected by aircraft and spacecraft. The University of Western Australia (UWA) is commissioning optical ground stations to support FSO communications payloads. We propose retroreflected laser links to drones as a useful step towards further ground-to-sky and ground-to-space FSO communications demonstrations. In this paper, we describe the operation of a hardware testbed for a high photon efficiency optical communication physical layer. This testbed was deployed over a slanted free space link to a drone to verify sub-systems required in communication between the ground station and a spacecraft in cis-Lunar space. Accomplishing this verification of the telescope pointing systems and communications systems would have otherwise been much harder or impossible without using a retroreflected drone link.
Publisher: American Astronomical Society
Date: 13-06-2017
Publisher: American Physical Society (APS)
Date: 06-05-2021
Start Date: 2024
End Date: 12-2026
Amount: $443,347.00
Funder: Australian Research Council
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