iXblue and Airbus Defence and Space developed a space-grade optical transceiver to increase communication rate between geostationary (GEO) or low earth orbit (LEO) satellites and earth. First demonstration model which will be launched early 2023 on a geostationary satellite possesses 2 downlink channels working at 10 Gb/s in non-return to zero differential phase shift keying (NRZ-DPSK), and 3 uplink demodulation channels. Two of them are dedicated to analog signals around 1 GHz, and one is dedicated for digital on-off keying (OOK) signal at 10 Gb/s.
Since the advent of the so-called “Newspace” approach, new actors of the space industry have replaced prudent space qualification by spectacular trial and error approaches. While such disruptive method generates emulation to reduce qualification, it remains that space industry face very challenging environmental stresses such as high mechanical requirements, operation in vacuum and radiations. The purpose of this paper is to give an overview of the application of Newspace methodology that has been applied for the demonstrator FOLC2.
Based on the experience acquired early from pioneering work at Stanford University and Thomson-CSF starting in the mid 70s, fiber optic gyro (FOG) R&D began at Photonetics in the late 80s to yield OCTANS, a FOG-based inertial strapdown system providing attitude and gyro compassing, at the end of the 90s. This FOG activity was spun out from Photonetics in October 2000 to create iXsea with only 16 people. The product line was rapidly expanded with PHINS, an inertial-grade INS (Inertial Navigation System) and later with MARINS, a strategic-grade INS, as well as with ASTRIX systems developed for satellites in cooperation with EADS-Astrium (today Airbus Defence & Space). In 2010, iXsea merged with several subsidiaries of its parent company, iXcore, to create iXblue. Among these subsidiaries were iXfiber, a maker of specialty fibers, and Photline, producing lithium-niobate integrated optics, hence allowing iXblue to fully master the key FOG components supply chain. Ten years later, the ‘adventure' is continuing and the former start-up is now quite a significant player in the inertial world, especially for high-grade applications. The cumulated number of high-performance 3-axis systems in service has grown to over 8,000, i.e. more than 25,000 FOG axes, with a bias stability ranging from 30 mdeg/h down to 15 μdeg/h, and an angular random walk (ARW) performance ranging from 8 mdeg/√h down to 40 μdeg/√h depending on the size of their sensing coils (3 m2 to 1000 m2) and on the application!
Integrated optic devices are nowadays achieving extremely high performances in the field of astronomical interferometry, as shown by the PIONIER and GRAVITY instruments. Progress remains to be made in order to increase the number of apertures/beams/channels to be combined (up to 9) and eventually ensure on-chip phase modulation (for fringe temporal scanning). We present a novel generation of beam combiners, based on the hybridization of two integrated optic devices: (i) one producing glass waveguides, that can ensure very sharp bend radius, high confinement and low propagation losses, with (ii) a lithium niobate device providing phase modulators and channel waveguides that can achieve on-chip, fast (<100kHz) phase modulation. The aim of this work is to compare three different concepts for the new generation FIRST/SUBARU 9T instrument, in terms of transmission, birefringence, half-wave voltage modulation and spectral range.
Integrated optic devices are nowadays achieving extremely good performances in the field of astronomical interferometry, as shown by PIONIER or GRAVITY silica/silicon-based instruments, already installed at VLTI. In order to address other wavelengths, increase the number of apertures to be combined and eventually ensure on-chip phase modulation, we are working on a novel generation of beam combiners, based on the hybridization of glass waveguides, that can ensure very sharp bend radius, high confinement and low propagation losses, together with lithium niobate phase modulators and channel waveguides that can achieve on-chip, fast (<100kHz) phase modulation. The work presented here has been realized in collaboration with our technological partners TeemPhotonics for glass waveguides and iXBlue-PSD for lithium niobate phase modulators. We will present our results on a hybrid glass/niobate (passive/active) beam combiner that has been developed in the context of FIRST/SUBARU 9T beam combiner. The combiner is structured in three parts: a) the first stage (passive glass) achieves beam splitting from one input to eight outputs, and that for nine input fibers coming from the sub-apertures of the Subaru telescope; b) the second stage consists on a 72 channel waveguides lithium niobate phase modulator in a push-pull configuration that allows to modify on-chip the relative phase between the 36 pairs of waveguides; c) a final recombination system of Y-junctions (passive glass) that allows to obtain combination of each input to every other one. The aim of this presentation is to discuss different issues of the combiners, such as transmission, birefringence, half-wave voltage modulation and spectral range.
We present easy-to-implement technologies to produce LiNbO3 PhCs in confined optical waveguides. Ti-indiffusion or
Annealed Proton Exchange (APE) are combined with optical grade dicing to fabricate ridge waveguides with
propagation losses that can be lower than 0.2 dB/cm. Firstly we show how a PhC inscribed in a confined ridge
waveguide can be exploited as a temperature sensor with an unexpectedly high 8 nm/°C temperature sensitivity. LiNbO3
PhCs with high aspect ratio are also demonstrated. The performance is achieved by properly tilting the ridge before
patterning its walls by Focused Ion Beam (FIB). A eight micrometer long 1D-PhC on a Ti:LiNbO3 ridge waveguide has
been fabricated and its reflectivity has been evaluated using an optical coherence tomography (OCT) system: it is
measured to be 53 % for the TM wave and 47 % for the TE wave. The period can be optimized in order to increase the
reflection of the 1D-PhC up to 80 %. These developments open the way to the dense integration of compact dynamic
devices such as modulators, spectral filters or electric field sensors.
We present our work on integrated optic beam combiners devoted to mid-infrared applications in the field of stellar
interferometry, in particular for nulling interferometry, where high rejection ratios are needed. The main results obtained are the single-mode behavior of the waveguides at a central wavelength λ=3.39μm, in both TE and TM polarization, a high rejection ratio on the modulated signal (best value of 30dB) and low dispersion in wide-band configuration. In a second time, in order to improve the electro-optic response of the modulators, we have realized a photonic crystal inside one of the arms of the Y-junction. Theoretical results predict simultaneous TE and TM group index enhancement, which should give better electro-optic response, however, our preliminary experimental results do not show significant difference with the initial combiners. Perspectives on the future work will be presented.
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