CASTOR is a proposed wide-field (30 ' x30 '=0.25 deg(2)), high-resolution (FWHM similar to 0.15 ''), 1-m-diameter space telescope that is under development by the Canadian Space Agency and the National Research Council of Canada. Optimized for UV/blue-optical wavelengths, the telescope uses dichroics to enable imaging in three channels (and up to five bands) that cover the 0.15 to 0.55 mu m spectral region, simultaneously. CASTOR will also feature low- and low-medium-resolution spectroscopic capabilities through the use of a deployable grism for low-resolution (R less than or similar to 420) slit-less spectroscopy in its UV and u channels, and low-medium-resolution R similar to 1400 multi-object spectroscopy in a parallel field using a digital micro-mirror device. High-speed, precision photometry will be possible using dedicated CMOS detectors in each of its three channels. We present an overview of the mission, including the optical design, instruments and detectors, payload layout, satellite bus, orbit, and ground segment. We describe the mission's scientific capabilities and expected place within the astronomical landscape in the 2030s. The 5-year lifetime is baselined on a combination of legacy surveys, guest observer programs, and target-of-opportunity science. We summarize scientific plans for the mission in each of eight fields: cosmology, time domain and multi-messenger science, active galactic nuclei, galaxies, near-field cosmology, stellar astrophysics, exoplanets, and solar system studies. We conclude by describing ongoing development efforts, highlighting areas of particular relevance for NASA's Habitable Worlds Observatory.

This paper provides an overview of the major quantum communications programs at Honeywell Aerospace. Honeywell Aerospace is implementing, on behalf of the Canadian Space Agency, the Quantum Encryption and Science Satellite (QEYSSat), a Canadian science and technology demonstration mission which aims to explore the next generation of secure communications infrastructure delivered via satellites. The QEYSSat mission will use a satellite receiver to demonstrate the distribution of secure keys on a global scale via uplink configuration. Planned experiments with the QEYSSat mission include long-range Bell tests of quantum entanglement, and demonstrations of quantum key distribution (QKD) between QEYSSat and several ground stations to provide a testbed for practical key distribution and management. QEYSSat will also be used to further develop the practicality of space-based quantum key distribution. The QEYSSat satellite will be capable of acting as both a weak coherent pulse transmitter as well as a receiver for both BB84 and BBM92 protocols. Honeywell also will fly a secondary laser communications terminal as a hosted payload on QEYSSat. This payload will serve as a flight demonstrator for Honeywell’s commercial inter-satellite and space-to-ground laser communications terminal. The secondary payload will be enabled to also support a weak coherent pulse downlink. In addition to heritage-building, the secondary payload will also serve as an operations demonstration for the upcoming QKDSat network.Beyond QEYSSat, Honeywell is implementing the QKDSat mission in a public-private partnership with the European Space Agency. The QKDSat program consists of an initial deployment of a single satellite and multiple user ground stations for the purposes of establishing an operational global quantum key distribution infrastructure capable of connecting ground-based quantum key distribution networks at scale. The hybrid laser communications terminals hosted on QKDSat are based on the QEYSSat secondary payload design and provide a high-rate BB84 downlink as well as a high-speed bidirectional classical communications channel.Beyond space segments, Honeywell is designing and building a network of ground stations to support both the QEYSSat and QKDSat programs. The QEYSSat mission is expected to operate in conjunction with an optical quantum ground station developed by Honeywell and the Institute for Quantum Computing, hosted by the Canadian Space Agency. The QKDSat mission focuses on a ground network which includes sites in the UK and continental Europe.This paper provides an overview of both the QEYSSat and QKDSat missions including the quantum payloads, ground segments, and the payload and mission-level performance indicators.

The demand for optical technologies in space is growing rapidly driven by the advent of low-earth orbit satellite “mega-constellations” providing global communication services. Free space optical communications between satellites in low earth orbit presents a number of technology challenges related to maintaining stable links between two satellites separated by thousands of kilometers. One principal challenge is the development of mechanically robust, mass-producible beam-steering technologies with low SWaP, and recurring cost. One potential solution to this challenge is to replace costly mechanical steering mechanisms with beam-steering elements such as on-chip optical phase arrays. This work presents ongoing research towards the development of an on-chip wide-steering optical phase array for inter-satellite communications. The presentation will cover the system architecture, component design, and control algorithms for synchronizing many emitters into a single output beam.

The first, to our knowledge, successful laboratory implementation of an approach to image winds using simultaneous (as opposed to sequential) fringe imaging of suitable isolated spectral emission lines is described. Achieving this in practice has been a long-standing goal for wind imaging using airglow. It avoids the aliasing effects of source irradiance variations that are possible with sequential fringe sampling techniques. Simultaneous fringe imaging is accomplished using a field-widened Michelson interferometer by depositing phase steps on four quadrants of one of the mirrors and designing an optical system so that four images of the scene of interest, each at a different phase, are simultaneously produced. In this paper, the instrument characteristics, its characterization, and the analysis algorithms necessary for use of the technique for this type of interferometer are described for the first time, to the best of our knowledge. The large throughput associated with field-widened Michelson interferometers is sufficient for the spatial resolutions and temporal cadences necessary for ground based imaging of gravity waves in wind and irradiance to be achieved. The practical demonstration of this technique also validates its use for proposed monolithic satellite instruments for wind measurements using airglow on the Earth and Mars.

Abstract. Electron-multiplying charge-coupled devices (EMCCDs) allow for subelectron effective read noise and thus for imaging at extremely low flux levels. In the ultraviolet, quantum yield creates an additional source of stochastic gain variation, which can be difficult to quantify using existing techniques. We propose a method for measuring the quantum yield gain of these devices, independent of existing methods, using images that are part of the existing test regimen for new EMCCDs. With this method, we were able to recover the quantum yield used to create simulated images within an accuracy of ∼5  %   and the method provided consistent results with test images after only minor modifications. However, the measured quantum yield remains anomalously low, consistent with other measurements on Teledyne-e2v devices. We hypothesize that this discrepancy is due to lateral transfer of secondary electrons between pixels at the surface explained by the band structure and crystal geometry of typical silicon wafers used in array detector manufacture.

Multiple emerging small satellite constellations aim to provide worldwide connectivity through high-speed free-space optical communication across many thousands of kilometers. The scale of these constellations requires a new approach to the design, build, and verification of high-performance space optics, one that will focus on mass-producibility, low-cost design, and limited touch-time. Honeywell and our partners have developed an optical intersatellite terminal that builds on our combined decades of experience in reliable space optics, electronics, and mass production of space hardware. The critical technical drivers of optical systems for space are their susceptibility to the thermal and radiation environments. The system is designed around Honeywell's Optical Pointing and Tracking Relay Assembly for Communications (OPTRAC), a low-cost sub-system which is designed to drive all of Honeywell's optical link products by providing a common interface between swappable front-end telescopes and back-end optical transceivers. The lowest-cost traditional approach to performing pointing and tracking is to apply quadrant photodiode sensors. These large-area devices have limited sensitivity and must maintain tight alignment tolerances over temperature. This chapter discusses the advantages and impacts of tracking with a pixelated sensor and presents results of laboratory testing and environmental qualification of a pixelated prototype subsystem.

Honeywell Aerospace has been selected by the Canadian Space Agency to implement the Quantum Encryption and Science Satellite (QEYSSat), a Canadian-owned and operated scientific and technology demonstration mission towards the next-generation of secure communications infrastructure. Quantum key distribution (QKD) is a method for distributing, via single-photon transfer, verifiably-confidential encryption keys between two parties separated by large distances. This capability is a powerful tool for the transmission of sensitive data (e.g. financial transactions, personal health records, etc.), however current ground-based QKD networks are limited in geographic reach to roughly 200 kilometres. The QEYSSat mission will use a satellite receiver to demonstrate the distribution of secure keys between ground stations separated by at least 400 km. In addition, Honeywell intends to fly an optical intersatellite link (OISL) terminal as a hosted payload on this mission. The QEYSSat mission will implement both weak coherent pulse (WCP) sources and entangled photon sources to study the performance of QKD, and to perform Bell tests of long-range quantum entanglement. Honeywell is building the free-space QKD terminal consisting of a large-diameter front-end telescope, a precision pointing and tracking system, single-photon receiver, and a downlink source. Major technical challenges include accurate pointing and tracking, polarization-management throughout the optical chain, and deep suppression of background and stray light sources, given the nature of single photon exchange over large distances. To address these challenges, Honeywell is leveraging its existing optical communications solutions to meet the enhanced performance requirements for space-based QKD. A large-format telescope for geostationary optical communications forms the basis for the terminal's front-end optics, and Honeywell's commercially-focused Optical Pointing and Tracking Relay Assembly for intersatellite Communications (OPTRAC) is being adapted as a high-performance, quantum-ready pointing and tracking unit (QTRAC). This paper discusses the design of the QKD terminal and will highlight results from the recently completed QEYSSat Phase A study.

We demonstrate a novel compressed sensing Fourier-transform spectrometer (FTS) in a compact format. This FTS consists of 160 planar-waveguide Mach-Zehnder interferometers (MZIs) arrayed on a photonic chip, effecting a discrete Fourier-transform of the input spectrum. Incoherence between the sampling domain, and the signal domain permits compressive sensing retrieval of sparse spectra using an undersampled measurement of the interferogram. In our fabricated device, we print a fraction of the MZIs required to form the full interferogram corresponding to our selected spectral bandwidth and resolution; the resulting system is undersampled by 1/4th the critical sampling rate, simultaneously reducing chip footprint and concentrating the interferogram in fewer pixels. We develop a scheme for multi-aperture broadband coupling to 83 single-mode waveguides using an array of microlenses bonded to the surface of the chip, and aligned with a grid of vertically illuminated waveguide apertures. The microlens array accepts a collimated beam with near 100% fill-factor, and the resulting spherical wavefronts are coupled into the single-mode waveguides using 45° mirrors etched into the waveguide layer via focused ion-beam. Interferograms from the waveguide outputs are imaged using a CCD, and inverted via l1-norm minimization to correctly retrieve sparse input spectra, verifying the instrument architecture and measurement principle.

Spatial heterodyne Fourier transform (SHFT) spectroscopy is based on simultaneous interferometric measurements implementing linearly increasing optical path differences, hence circumventing the need for mechanical components of traditional Fourier transform spectroscopy schemes. By taking advantage of the high mode confinement of the Silicon-on-Insulator (SOI). platform, great interferometric lengths can be implemented in a reduced footprint, hence increasing the resolution of the device. However, as resolution increases, spectrometers become progressively more sensitive to environmental conditions, and new spectral retrieval techniques are required. In this work, we present several software techniques that enhance the operation of high-resolution SHFT micro-spectrometers. Firstly, we present two techniques for mitigating and correcting the effects of temperature drifts, based on a temperature-sensitive calibration and phase errors correction. Both techniques are demonstrated experimentally on a 32 Mach-Zehnder interferometers array fabricated in a Silicon-on-insulator chip with microphotonic spirals of linearly increasing length up to 3.779 cm. This configuration provides a resolution of 17 pm in a compact device footprint of 12 mm(2). Secondly, we propose the application of compressive-sensing (CS) techniques to SHFT micro-spectrometers. By assuming spectrum sparsity, an undersampled discrete Fourier interferogram is inverted using l1-norm minimization to retrieve the input spectrum. We demonstrate this principle on a subwavelength-engineered SHFT with 32 MZIs and a 50 pm resolution. Correct retrieval of three sparse input signals was experimentally demonstrated using data from 14 or fewer MZIs and applying common CS reconstruction techniques to this data.

We have built a novel planar-waveguide Fourier-transform spectrometer (FTS) with several innovative design features to achieve high throughput Raman spectroscopy in a compact layout. This waveguide FTS consists of a set of independent Mach-Zehnder interferometers (MZIs) on a photonic chip. An array of microlenses is bonded to the ‘bottom’ surface of the chip, transforming a normally incident collimated beam into an array of focal spots near the waveguide surface. These micro-beams are deflected using an array of focused ion-beam (FIB) etched 45 degree mirrors into an array of single mode waveguides. Because the features of a Raman spectrum are sparsely distributed in frequency space, we are able to adapt techniques of compressive-sensing (CS) spectroscopy to significantly undersample the interferogram at our chosen bandwidth and resolution. The resulting system reduces the number of waveguides (MZIs) required by a factor of 4 while simultaneously reducing the size of the spectrometer and concentrating the Raman signal in a smaller number of detector pixels for further signal to noise enhancement. Because the interferogram samples are gathered simultaneously, a gated detector can be used to separate Raman peaks from sample fluorescence.

We demonstrate compressive-sensing (CS) spectroscopy in a planar-waveguide Fourier-transform spectrometer (FTS) device. The spectrometer is implemented as an array of Mach-Zehnder interferometers (MZIs) integrated on a photonic chip. The signal from a set of MZIs is composed of an undersampled discrete Fourier interferogram, which we invert using l1-norm minimization to retrieve a sparse input spectrum. To implement this technique, we use a subwavelength-engineered spatial heterodyne FTS on a chip composed of 32 independent MZIs. We demonstrate the retrieval of three sparse input signals by collecting data from restricted sets (8 and 14) of MZIs and applying common CS reconstruction techniques to this data. We show that this retrieval maintains the full resolution and bandwidth of the original device, despite a sampling factor as low as one-fourth of a conventional (non-compressive) design.

Electron multiplying charged coupled devices (EMCCD’s) can provide significantly greater signal to noise ratios in low light conditions and/or for higher speed readout than traditional CCDs. Due to the electron multiplication before readout, the effective readout noise can be at the sub-electron level, enabling single photon counting. Traditional far UV (150 – 200 nm) imaging detectors have utilized micro-channel plates to detect usually scarce UV photons at low efficiency, amplify them into electron showers which strike a phosphor, allowing a silicon detector array to perform the final detection of the resulting visible light pulse. The typical efficiencies of UV photo detection with MCP systems ranges from a low of a few percent to as high as 25%. Given that the theoretical probability of absorption of UV photons in silicon is at least 30% in this wavelength range, then it should be possible to make use of a photon counting EMCCD to directly detect UV photons that is competitive with MCP performance. We approached Teledyne-e2v and they confirmed that a backside thinned EMCCD with their ‘astro no-coat’ process should provide reasonable quantum efficiency (ie. > 30%) in this range. The primary application in which we are interested is UV imaging of the aurora from space-based platforms. In this application there are system level advantages to replacing an MCP based detector with an EMCCD which is directly sensitive to UV illumination, namely the elimination of a high voltage power supply and higher spatial resolution. An MCP produces an electron shower which degrades image quality and also requires a relatively thick detector window which has to be accommodated in the imager optical design. We acquired five CCD201 engineering model EMCCDs with e2v’s ‘astro no-coat’ process, and incorporated one of these into a standard flexible liquid nitrogen cooled EMCCD camera produced by Nüvü Camēras. Once installed the EMCCD operation was confirmed with standard Nüvü Camēras test procedures. The camera was then mounted in a test vacuum chamber along with a McPherson UV monochromator so that the UV performance could be assessed. A NIST traceable photodiode was used for the absolute calibration. The resulting intrinsic QE was found to be 34% at 180 nm rising to 44% at 150 nm. The quantum yield was found to be quite low, only a few percent at 180 nm rising to only 1.13-1.18 at 150 nm. This is considerably lower than comparable results from CCDs where delta-doping has been used to improve the responsive quantum efficiency and also lower than a Teledyne-e2v CMOS sensor with the same surface treatment.

Single-photon detectors in space must retain useful performance characteristics despite being bombarded with sub-atomic particles. Mitigating the effects of this space radiation is vital to enabling new space applications which require high-fidelity single-photon detection. To this end, we conducted proton radiation tests of various models of avalanche photodiodes (APDs) and one model of photomultiplier tube potentially suitable for satellite-based quantum communications. The samples were irradiated with 106 MeV protons at doses approximately equivalent to lifetimes of 0.6, 6, 12 and 24 months in a low-Earth polar orbit. Although most detection properties were preserved, including efficiency, timing jitter and afterpulsing probability, all APD samples demonstrated significant increases in dark count rate (DCR) due to radiation-induced damage, many orders of magnitude higher than the 200 counts per second (cps) required for ground-to-satellite quantum communications. We then successfully demonstrated the mitigation of this DCR degradation through the use of deep cooling, to as low as -86 degrees C. This achieved DCR below the required 200 cps over the 24 months orbit duration. DCR was further reduced by thermal annealing at temperatures of +50 to +100 degrees C.

We demonstrate a passively thermally-stabilized planar waveguide Fourier-transform spectrometer for remote detection of atmospheric methane. The device is implemented as a spatial heterodyne spectrometer using an array of 100 Mach-Zehnder interferometers (MZIs) on an integrated photonic chip. The spectrometer is buffered against temperature fluctuations by using waveguides with a carefully engineered, athermal geometry. The achieved waveguide thermooptic optic coefficient is 3.5 x 10(-6)K(-1). Effective entrance aperture is increased over dispersive element spectrometers, without sacrificing spectral resolution, by coupling light independently to each of the 100 MZIs. The output of each MZI is sampled in quadrature, to compensate for non-uniform illumination across the MZI input apertures. The spectrometer is validated using a methane reference cell in a benchtop setup: an interferogram is inverted via least-squares spectral analysis (LSSA) to retrieve multiple absorption lines at a spectral resolution of 50 pm over a 1 nm free spectral range (FSR) centered at lambda(0) = 1666.5 nm. The retrieved spectrum is compared against the Beer-Lambert absorption law and is found to provide a correct measurement of the volume mixing ratio (VMR) in the optical path. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

We present two techniques for mitigating the effects of temperature drifts in waveguide spatial heterodyne Fourier-transform on-chip spectrometers. In high-resolution devices, large optical path length differences result in an increased sensitivity to temperature variations and impose stringent requirements on the thermal stabilization system. In order to overcome this limitation, here we experimentally demonstrate two new temperature mitigation techniques based on a temperature-sensitive calibration and phase error correction. The spectrometer chip under analysis comprises an array of 32 Mach-Zehnder interferometers fabricated on a silicon-on-insulator platform. The optical path delays are implemented as microphotonic spirals of linearly increasing length up to 3.779 cm, yielding a spectral resolution of 17 pm. We demonstrate that the degradation in retrieved spectra caused by temperature drift is effectively eliminated by temperature-sensitive calibration and phase error correction.