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.
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!
This paper presents the technical solutions implemented with the support of the French Space Agency (CNES) to design and manufacture hermetic Lithium Niobate (LiNbO3: LN) modulators, in the framework of a Research & Technology (R&T) project [1]. There is also presented some identified space-compatible raw materials that constitute modulators and some relevant results of a space evaluation program realized on about fifteen of these hermetic modulators (including hermeticity tests, mechanical tests and climatic tests).
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.
Silicon photonics technology is an enabler for the integration of complex circuits on a single chip, for various optical link applications such as routing, optical networks on chip, short range links and long haul transmitters. Quadrature Phase Shift Keying (QPSK) transmitters is one of the typical circuits that can be achieved using silicon photonics integrated circuits. The achievement of 25GBd QPSK transmitter modules requires several building blocks to be optimized: the pn junction used to build a BPSK (Binary Shift Phase Keying) modulator, the RF access and the optical interconnect at the package level. In this paper, we describe the various design steps of a BPSK module and the related tests that are needed at every stage of the fabrication process.
In this work we demonstrate two new BOTDA sensing systems based on differential (DPSK) and quadrature
(QPSK) phase-shift keying modulation techniques with enhanced performances. First we demonstrate Brillouin
echoes distributed sensing (BEDS) with centimeter resolution using a single intensity DPSK modulator for the
pump pulse. The optical π-phase pulse is directly generated at the end of an intensity pulse using DPSK
technique. This allows an easy adjustment of the delay between the intensity and phase pulse and improves the
optical loss of the pump. The second technique uses an optical QPSK modulator (I & Q modulator) as a single
sideband (SSB) modulator. The advantage of I & Q modulator compared to dual-drive modulator lies on the
high performance of carrier suppression of 55 dB as well as side-mode suppression of 40 dB at 1535 nm. Besides
the filter that chooses either the Stokes or anti-Stokes component before detecting the Brillouin response on the
photodiode is no more needed. By use of the I & Q modulator the performance of BOTDA using either Stokes
or anti-Stokes component is shown and discussed.
We report two novel kinds of LiNbO3 electro-optic modulators. The first one is oriented toward long haul high bit rate telecommunication systems. An original single-ended structure with a poled section and phase reversal electrodes is proposed to prevent the intensity modulation from chirp, without sacrifice on the driving voltage. We also show that improvements can be performed with the use of several poled sections. To remain attracting, LiNbO3 modulators should also exhibit a lower size. The second configuration described here is a new generation of LiNbO3 modulators based on photonic crystals, with a micrometric active length. We theoretically show that the optimal photonic structures for an efficient electro-optical tuning are based on a triangular array of holes integrated on a X-cut substrate. The first optical characterizations confirm the theoretical predictions, and exhibit a -12dB extinction ratio in the transmission response.
Second Harmonic Generation (SHG) using counter-propagating Quasi Phase Matching (QPM) configuration often
requires a fine non-linearity with a period of a fraction of a micrometer. The direct Electron Beam (EB) domain reversal
technique seems to be promising to achieve gratings on LiNbO3 with such a small period compared to other current poling
technologies as it is lithographic free and exhibits a very high theoretical resolution (5 mm).
We present here, a preliminary study concerning the influence of EB irradiation conditions on domain inversion;
SHG is also examined on a 6.58 j.tm inverted periodic domain grating in lithium niobate using a Nd-YaG laser light.
It is well known that LiNbO3 is an attractive material for many optical applications because of its transparency over
a large wavelength band (350 mm to 5000 mm) and its high nonlinear coefficients. EB irradiation is performed using a
Scanning Electron Microscope (SEM) driven by a Computer Aided Design (CAD) application developed in our laboratory.
Various structures such as periodic gratings can be written with the chosen period. The ferroelectric domain inversion is
investigated as a function of the accelerating voltage of the electrons (10 to 30 kV), the scanning speed of the EB (0.97 to
7.76 mm/s) and the current received by the sample (1.6 to 14 nA). The inversion patterns have been revealed by chemical
etching (HF) and they have been observed using SEM. It has been shown that the duty cycle is respected on the irradiated
face. The SHG conversion efficiency is measured as a function of the temperature and the grating period is calculated (value
of6.564 jim).
In this paper, we report second harmonic generation in a tunable/Q-switch Nd3+-doped fiber laser using a LiNbO3-integrated optics device. The component is a low-voltage asymmetric Mach-Zehnder Interferometer. Laser emission occurs simultaneously at two wavelengths (lambda) 0 equals 1088 nm et (lambda) 2 equals 544 nm. As a driving voltage is applied to the LiNbO3 component, the lasing wavelengths are tuned by mode hopping. We demonstrate a Q-switch mode operating of that laser.
We present in this paper recent results obtained in the field of bidirectional transmissions, coherence multiplexing, and integrated optics. We report the description of a new kind of Mach-Zehnder interferometer integrated in lithium niobate (LiNbO3), which is the key device of a coherence multiplexed bidirectional link. The orientation of the waveguides, parallel to the Z-axis of LiNbO3, yields a polarization independent behavior. The working conditions of the modulators and the results obtained as they are used in a full-duplex bidirectional link are presented.
We report the description of a new kind of Mach-Zehnder interferometers integrated in lithium niobate (LiNbO3), which can be used for sensor applications and coherence multiplexing transmission systems. These modulators are designed to introduce large optical delays, of some tens to some hundreds of micrometers. The orientation of the waveguides, parallel to the Z-axis of LiNbO3, allows a quasi-polarization independent behavior.
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