41 research outputs found
Optical fibre transitions for device applications
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
The Photonic TIGER: a multicore fiber-fed spectrograph
We present a proof of concept compact diffraction limited high-resolution
fiber-fed spectrograph by using a 2D multicore array input. This high
resolution spectrograph is fed by a 2D pseudo-slit, the Photonic TIGER, a
hexagonal array of near-diffraction limited single-mode cores. We study the
feasibility of this new platform related to the core array separation and
rotation with respect to the dispersion axis. A 7 core compact Photonic TIGER
fiber-fed spectrograph with a resolving power of around R~31000 and 8 nm
bandwidth in the IR centered on 1550 nm is demonstrated. We also describe
possible architectures based on this concept for building small scale compact
diffraction limited Integral Field Spectrographs (IFS).Comment: 8 pages, 6 figures, SPIE Astronomical Telescopes and Instrumentation
8450-5
Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application
Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few-mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r(sub 0)=8.6. Furthermore, the coupling loss of the few-mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array
A Multi-Core Fibre Photonic Lantern-Based Spectrograph for Raman Spectroscopy
[EN] We report on the development of a compact (volume approximate to 100 cm(3)), multimode diffraction-limited Raman spectrograph and probe designed to be compact as possible. The spectrograph uses 'off the shelf' optics, a custom 3D-printed two-part housing and harnesses a multi-core fibre (MCF) photonic lantern (multimode to few-mode converter), which slices a large 40 mu m multimode input into a near-diffraction-limited 6 mu m aperture. Our unique design utilises the hexagonal geometry of our MCF, permitting high multimode collection efficiency with near-diffraction-limited performance in a compact design. Our approach does not require a complex reformatter or mask and thus preserves spectral information and throughput when forming the entrance slit of the spectrograph. We demonstrate the technology over the interval 800 nm to 940 nm (200 cm(-1) to 2000 cm(-1)) with a resolution of 0.3 nm (4 cm(-1)), but other spectral regions and resolutions from the UV to the near infrared are also possible. We demonstrate the performance of our system by recording the Raman spectra of several compounds, including the pharmaceuticals paracetamol and ibuprofen.This work was supported in part by the University of Sydney under Grant SREI 2020 and in part by JBH's ARC Laureate Fellowship under Grant FL140100278.Betters, CH.; Bland-Hawthorn, J.; Sukkarieh, S.; Gris-Sánchez, I.; Leon-Saval, SG. (2020). A Multi-Core Fibre Photonic Lantern-Based Spectrograph for Raman Spectroscopy. IEEE Photonics Technology Letters. 32(7):395-398. https://doi.org/10.1109/LPT.2020.2976599S39539832
Holey fibre mode-selective couplers
Mode-selective coupling in an asymmetric holey fibre coupler is demonstrated both numerically and experimentally for the first
time. The coupler's performance is shown to be ultrabroadband, with significant potential existing for the use of such
couplers in high bandwidth few-mode fibre networks
Measurements of Few-Mode Fiber Photonic Lanterns in Emulated Atmospheric Conditions for a Low Earth Orbit Space to Ground Optical Communication Receiver Application
Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r0=8.6. Furthermore, the coupling loss of the few mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array
All-fiber mode-group-selective photonic lantern using graded-index multimode fibers
We demonstrate the first all-fiber mode-group-selective photonic lantern using multimode graded-index fibers. Mode selectivity for mode groups LP01, LP11 and LP21 + LP02 is 20-dB, 10-dB and 7-dB respectively. The insertion loss when butt coupled to multimode graded-index fiber is below 0.6-dB. The use of the multimode graded-index fibers in the taper can significantly reduce the adiabaticity requirement
GNOSIS: the first instrument to use fibre Bragg gratings for OH suppression
GNOSIS is a prototype astrophotonic instrument that utilizes OH suppression
fibres consisting of fibre Bragg gratings and photonic lanterns to suppress the
103 brightest atmospheric emission doublets between 1.47-1.7 microns. GNOSIS
was commissioned at the 3.9-meter Anglo-Australian Telescope with the IRIS2
spectrograph to demonstrate the potential of OH suppression fibres, but may be
potentially used with any telescope and spectrograph combination. Unlike
previous atmospheric suppression techniques GNOSIS suppresses the lines before
dispersion and in a manner that depends purely on wavelength. We present the
instrument design and report the results of laboratory and on-sky tests from
commissioning. While these tests demonstrated high throughput and excellent
suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS
produced no significant reduction in the interline background and the
sensitivity of GNOSIS and IRIS2 is about the same as IRIS2. It is unclear
whether the lack of reduction in the interline background is due to physical
sources or systematic errors as the observations are detector noise-dominated.
OH suppression fibres could potentially impact ground-based astronomy at the
level of adaptive optics or greater. However, until a clear reduction in the
interline background and the corresponding increasing in sensitivity is
demonstrated optimized OH suppression fibres paired with a fibre-fed
spectrograph will at least provide a real benefits at low resolving powers.Comment: 15 pages, 13 figures, accepted to A