Room-Temperature operation of a quantum well mid-infrared detector embedded in nano-antennae array at critical optical coupling

We present the first room temperature photodection of hundreds on nanowatts using a quantum well mid-infrared detector at 9μm, with a background-limited temperature of 82K and a corresponding background-limited specific detectivity of 1.4×1010 cmHz1/2/W. The photonic architecture consists of an array of double metal nano-antennae and allows to reduce the dark current and increase the absorbed electromagnetic field inside the active region, so to prove a high temperature photoresponse

Mixing Properties of Room Temperature Patch‐Antenna Receivers in a Mid‐Infrared (λ ≈ 9 µm) Heterodyne System

A room‐temperature mid‐infrared (λ = 9 µm) heterodyne system based on high‐performance unipolar optoelectronic devices is presented. The local oscillator (LO) is a quantum cascade laser (QCL), while the receiver is an antenna coupled quantum well infrared photodetector optimized to operate in a microcavity configuration. Measurements of the saturation intensity show that these receivers have a linear response up to very high optical power, an essential feature for heterodyne detection. By providing an accurate passive stabilization of the LO, the heterodyne system reaches at room temperature the record value of noise equivalent power (NEP) of 30 pW at 9 µm and in the GHz frequency range. Finally, it is demonstrated that the injection of microwave signal into the receivers shifts the heterodyne beating over the large bandwidth of the devices. This mixing property is a unique valuable function of these devices for signal treatment in compact QCL‐based systems

High sensitivity 9μm metamaterial Infrared QC detectors at 300K

Quantum Cascade Detectors are promising devices for high-temperature mid-infrared detection. The responsivity, related to its photovoltaic working principle, still suffers from lower responsivity respect to a photoconductive device such as QWIP. Here, we demonstrate that inserting a QCD detector in a photonic metamaterial made of patch-antenna microcavities, we can boost light-matter interaction reaching responsivity value in the order of 50mA/W at room temperature, the highest value reported in the literature

Asgard/NOTT: L-band nulling interferometry at the VLTI I. Simulating the expected high-contrast performance

Context: NOTT (formerly Hi-5) is a new high-contrast L' band (3.5-4.0 \textmu m) beam combiner for the VLTI with the ambitious goal to be sensitive to young giant exoplanets down to 5 mas separation around nearby stars. The performance of nulling interferometers in these wavelengths is affected both by fundamental noise from the background and by the contributions of instrumental noises. This motivates the development of end-to-end simulations to optimize these instruments. Aims: To enable the performance evaluation and inform the design of such instruments on the current and future infrastructures, taking into account the different sources of noise, and their correlation. Methods: SCIFYsim is an end-to-end simulator for single mode filtered beam combiners, with an emphasis on nulling interferometers. It is used to compute a covariance matrix of the errors. Statistical detection tests based on likelihood ratios are then used to compute compound detection limits for the instrument. Results: With the current assumptions on the performance of the wavefront correction systems, the errors are dominated by correlated instrumental errors down to stars of magnitude 6-7 in the L band, beyond which thermal background from the telescopes and relay system becomes dominant. Conclusions: SCIFYsim is suited to anticipate some of the challenges of design, tuning, operation and signal processing for integrated optics beam combiners. The detection limits found for this early version of NOTT simulation with the unit telescopes are compatible with detections at contrasts up to $10^5$ in the L band at separations of 5 to 80 mas around bright stars

Room-temperature nine-µm-wavelength photodetectors and GHz-frequency heterodyne receivers

Room-temperature operation is essential for any optoelectronics technology that aims to provide low-cost, compact systems for widespread applications. A recent technological advance in this direction is bolometric detection for thermal imaging¹, which has achieved relatively high sensitivity and video rates (about 60 hertz) at room temperature. However, owing to thermally induced dark current, room-temperature operation is still a great challenge for semiconductor photodetectors targeting the wavelength band between 8 and 12 micrometres², and all relevant applications, such as imaging, environmental remote sensing and laser-based free-space communication³,⁴,⁵, have been realized at low temperatures. For these devices, high sensitivity and high speed have never been compatible with high-temperature operation⁶,⁷. Here we show that a long-wavelength (nine micrometres) infrared quantum-well photodetector⁸ fabricated from a metamaterial made of sub-wavelength metallic resonators⁹,¹⁰,¹¹,¹² exhibits strongly enhanced performance with respect to the state of the art up to room temperature. This occurs because the photonic collection area of each resonator is much larger than its electrical area, thus substantially reducing the dark current of the device¹³. Furthermore, we show that our photonic architecture overcomes intrinsic limitations of the material, such as the drop of the electronic drift velocity with temperature¹⁴,¹⁵, which constrains conventional geometries at cryogenic operation⁶. Finally, the reduced physical area of the device and its increased responsivity allow us to take advantage of the intrinsic high-frequency response of the quantum detector⁷ at room temperature. By mixing the frequencies of two quantum-cascade lasers¹⁶ on the detector, which acts as a heterodyne receiver, we have measured a high-frequency signal, above four gigahertz (GHz). Therefore, these wide-band uncooled detectors could benefit technologies such as high-speed (gigabits per second) multichannel coherent data transfer¹⁷ and high-precision molecular spectroscopy¹⁸

High-angular and high-contrast VLTI observations from Y to M band with the Asgard instrumental suite

This is the final version. Available from SPIE via the DOI in this recordSPIE Astronomical Telescopes + Instrumentation 2022, 17 - 22 July 2022, Montreal, CanadaThe Very Large Telescope Interferometer is one of the most proficient observatories in the world for high angular resolution. Since its first observations, it has hosted several interferometric instruments operating in various bandwidths in the infrared. As a result, the VLTI yields countless discoveries and technological breakthroughs. We introduce to the VLTI the new concept of Asgard: an instrumental suite including four natively collaborating instruments: BIFROST, a stellar interferometer dedicated to the study of the formation of multiple systems; Hi- 5, a nulling interferometer dedicated to imaging young nearby planetary systems in the M band; HEIMDALLR, an all-in-one instrument performing both fringe tracking and stellar interferometry with the same optics; Baldr, a fibre-injection optimiser. These instruments share common goals and technologies. Thus, the idea of this suite is to make the instruments interoperable and complementary to deliver unprecedented sensitivity and accuracy from J to M bands. The interoperability of the Asgard instruments and their integration in the VLTI are the main challenges of this project. In this paper, we introduce the overall optical design of the Asgard suite, the different modules, and the main challenges ahead.European Union Horizon 2020Science and Technology Facilities Council (STFC)European Research Council (ERC

2023 Astrophotonics Roadmap: pathways to realizing multi-functional integrated astrophotonic instruments

This is the final version. Available on open access from IOP Publishing via the DOI in this recordData availability statement: The data that support the findings of this study are available upon reasonable request from the authors.Photonic technologies offer numerous functionalities that can be used to realize astrophotonic instruments. The most spectacular example to date is the ESO Gravity instrument at the Very Large Telescope in Chile that combines the light-gathering power of four 8 m telescopes through a complex photonic interferometer. Fully integrated astrophotonic devices stand to offer critical advantages for instrument development, including extreme miniaturization when operating at the diffraction-limit, as well as integration, superior thermal and mechanical stabilization owing to the small footprint, and high replicability offering significant cost savings. Numerous astrophotonic technologies have been developed to address shortcomings of conventional instruments to date, including for example the development of photonic lanterns to convert from multimode inputs to single mode outputs, complex aperiodic fiber Bragg gratings to filter OH emission from the atmosphere, complex beam combiners to enable long baseline interferometry with for example, ESO Gravity, and laser frequency combs for high precision spectral calibration of spectrometers. Despite these successes, the facility implementation of photonic solutions in astronomical instrumentation is currently limited because of (1) low throughputs from coupling to fibers, coupling fibers to chips, propagation and bend losses, device losses, etc, (2) difficulties with scaling to large channel count devices needed for large bandwidths and high resolutions, and (3) efficient integration of photonics with detectors, to name a few. In this roadmap, we identify 24 key areas that need further development. We outline the challenges and advances needed across those areas covering design tools, simulation capabilities, fabrication processes, the need for entirely new components, integration and hybridization and the characterization of devices. To realize these advances the astrophotonics community will have to work cooperatively with industrial partners who have more advanced manufacturing capabilities. With the advances described herein, multi-functional integrated instruments will be realized leading to novel observing capabilities for both ground and space based platforms, enabling new scientific studies and discoveries.National Science Foundation (NSF)NAS

High speed quantum well infrared heterodyne receivers at 4.9μm

International audienc

Long-wavelength infrared photovoltaic heterodyne receivers using patch-antenna quantum cascade detectors

Quantum cascade detectors (QCDs) are unipolar infrared devices where the transport of the photoexcited carriers takes place through confined electronic states, without an applied bias. In this photovoltaic mode, the detector's noise is not dominated by a dark shot noise process, and therefore, performances are less degraded at high temperature with respect to photoconductive detectors. This work describes a 9 μm QCD embedded into a patch-antenna metamaterial, which operates with state-of-the-art performances. The metamaterial gathers photons on a collection area, Acoll, much larger than the geometrical area of the detector, improving the signal to noise ratio up to room temperature. The background-limited detectivity at 83 K is 5.5 × 1010 cm Hz1/2 W−1, while at room temperature, the responsivity is 50 mA/W at 0 V bias. A patch antenna QCD is an ideal receiver for a heterodyne detection setup, where a signal at a frequency of 1.4 GHz and T = 295 K is reported as demonstration of uncooled 9 μm photovoltaic receivers with a GHz electrical bandwidth. These findings guide the research toward uncooled IR quantum limited detection