Orthogonal polarization fiber optic gyroscope with improved bias drift

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (leaf 57).by Melody A. Lynch.M.Eng

Development of an Extrinsic dual-cavity Fiber Fabry-Perot interferometer : Applications to periodic and non-periodic vibration measurements

Le travail présenté dans cette thèse concerne le développement et la caractérisation d'un interféromètre extrinsèque à double cavités de type Fabry-Perot (EFFPI) en vue de l'analyse de vibrations périodiques et non périodiques. Cette thèse est divisée en 5 chapitres. Dans le chapitre I, nous donnons un panorama des mesures de vibration et de leurs techniques associées de type optique ou non-optique. Nous fournissons une description générale des caractéristiques des interféromètres à fibre optique. Nous justifions le choix du système de type Fabry-Perot par ses propriétés de mesure sans contact, sa flexibilité géométrique, ainsi que sa facilité d'utilisation. Le chapitre II présente le principe de fonctionnement du EFFPI. Le système comprend une cavité virtuelle pseudo-duale obtenue par l'introduction d'une optique de polarisation dans le chemin optique de la cavité de mesure. Cette configuration permet d'obtenir deux signaux d'interférence en quadrature, ce qui élimine l'ambiguïté de direction. Les propriétés générales de l'interféromètre telles que la réflectance et la visibilité de franges ont été caractérisées expérimentalement. En particulier, les états de polarisation des faisceaux d'entrée et de sortie ont été étudiés pour mieux comprendre l'atténuation induite dans les signaux d'interférence afin de pouvoir minimiser ce phénomène. Dans le chapitre III, nous proposons une technique de démodulation de franges de type passage à zéro modifiée pour obtenir l'information de déplacement. La résolution obtenue dans cette technique de démodulation est déterminée par le nombre de sous-niveaux de décomposition des signaux d'interférence. Dans ce travail, une résolution de λ/64 s'est avérée suffisante pour des applications à des vibrations périodiques de relativement grande amplitude. Différentes excitations de type sinusoïdal, carré et triangulaire ont été testées. Les erreurs provoquées par la variation de température de la source laser ainsi que celles apportées par la variation d'orientation de la cible durant la mesure de déplacement ont été étudiées. Dans le chapitre IV, nous décrivons une technique de démodulation à poursuite de phase pouvant opérer sur une cible soumise à un déplacement non-périodique. Le développement d'un programme de simulation et de démodulation a permis l'analyse des erreurs de phase, l'effet du bruit aléatoire et du bruit de quantification, etc. Les erreurs de phase peuvent être corrigées par le démodulateur alors que les erreurs dues au bruit peuvent être réduites par une méthode de correction d'amplitude. Des tests expérimentaux réalisés à partir d'excitations de type carré avec un transducteur piézo-électrique (PZT) muni d'un capteur capacitif ont montré un très bon accord sur les mesures (différence de quelques nanomètres seulement). Nous avons utilisé le EFFPI pour deux applications spécifiques. En sismométrie, nous avons montré son aptitude à la mesure d'amplitude et de vitesse des vibrations. Dans une seconde application, le système a permis de mesurer de façon précise les variations de niveau d'un liquide dans un système d'inclinomètrie optique basée sur le principe des vases communicants. Le dernier chapitre donne les conclusions sur le travail réalisé et propose des perspectives afin d'améliorer les performances du capteur développé. ABSTRACT : The work involved in this thesis principally concerns the development and characterization of a dual-cavity Extrinsic Fiber Fabry-Perot Interferometer (EFFPI), with the specific aims of analyzing both periodic and non-periodic vibrations. This thesis is divided into five chapters. In chapter I, we provide a brief overview of vibration measurements and their associated techniques, both optical and non-optical. A general description of the characteristics of fiber optic interferometers most suited for this application is next included. The emphasis on non-contact measurement, geometrical flexibility, accessibility to the mesurand in question and the ease of deployment orientates our choice towards the fiber Fabry-Perot device. Chapter II presents the operating principles of the EFFPI. The device contains a “virtual” pseudo-dual-cavity which is generated due to the introduction of polarization-controlling optics into the optical path of the sensing cavity. This configuration enables two sets of “quadrature phase-shifted” interference signals to be obtained, hence eliminating the problem of directional ambiguity. The general properties of the interferometer, such as its reflectance and fringe visibility, have been characterized. More importantly, the polarization states of the injected and output lightwaves have been studied to further understand polarization-induced signal attenuation with the aim of reducing this parasitic effect. A modified zero-crossing fringe demodulation technique is described in chapter III for processing the interference signals from the dual-cavity EFFPI sensor into useful displacement information. The resolution of the demodulation scheme is determined by the number of sub-levels into which the interference fringes can be divided. In this work, a λ/64 resolution is deemed sufficient for application in periodic vibrations with relatively large amplitudes. Various signal types, such as sinusoidal, square, and triangular excitations have been applied and experimentally verified. Possible errors due to temperature variation of the laser source as well as the target orientation during displacement measurements are also investigated. In chapter IV, a phase-tracking technique is described for demodulating the interference signals into the required/desired displacement of a target subjected to non-periodic vibration. The development of a simulation and demodulation program enables the analysis of out-of-quadrature phase errors, random noise effects, quantization noise, etc. The detected phase errors can subsequently be corrected by the demodulator while the noise can be reduced via an amplitude correction method. Experimental tests under squarewave excitation carried out with a PieZo-electric Transducer (PZT) incorporating a capacitive sensor demonstrated excellent agreement (difference of only a few nanometers). The EFFPI sensor is next employed for two specific applications. In seismometry, the possibility of our sensor for detecting both vibration amplitudes and velocities is aptly demonstrated. In addition, the fiber sensor is also shown to be relatively accurate in measuring liquid level variation in an optical inclinometry set-up based on two communicating short-base vases. The final chapter concludes the work carried out in this thesis and proposes perspectives for further enhancing the performance of the developed senso

Devices for satellite-assisted quantum networks

Quantum networks, quantum nodes interconnected by quantum channels, offer powerful means of secure communications and quantum computations. They are crucial elements in a broad area of quantum technologies including quantum simulations and metrologies. In particular, quantum links with satellites take the network into a global or greater scale, extending the capability of transmitting information. It also provides experimental platforms of testing quantum physics in a relativistic regime. The realization of satellite-assisted quantum networks requires devices that are interfaced with quantum optical channels to satellites. This thesis discusses the development of four essential devices, three of which are in line with Canada's Quantum Encryption and Science Satellite (QEYSSat) mission. First, polarization-entangled photon sources are developed to transmit one of the paired photons over ground-based fiber-optic networks and the other over ground-to-satellite free-space links. A practical and versatile interferometric scheme is designed and demonstrated, which allows constructing highly non-degenerate sources with only conventional polarization optics. A method of directly producing entangled photon-pairs from optical fibers without interferometers is studied with thorough numerical analysis to show feasibility of experimental demonstration. An entangled photon source for the QEYSSat mission is conceptually designed, and several key parameters to fulfill a set of performance requirements are theoretically studied and experimentally verified. Secondly, this thesis presents two characterization platforms for optical components that are designed and implemented for the QEYSSat mission. One is to precisely measure transmitted wavefronts of large optics including telescopes. A proof-of-principle experiment is conducted with accurate modelling of measurement apparatus via three-dimensional raytracing, and quantitative agreement between the experiment and simulations validates our methodology. The other provides polarization characterizations for a variety of optical components including lenses, mirrors, and telescopes with consistent precision. A detailed description of subsystems including calibrations and test procedures is provided. Polarization-test results of several components for the QEYSSat are discussed. Third, quantum frequency transducers are developed for single-photon quantum key distributions with QEYSSat links. The devices are designed to translate the wavelength of single-photons emitted from quantum dot single-photon sources to QEYSSat channel wavelength via four-wave mixing Bragg-scattering process. Two optical media are concerned: a silicon nitride ring resonator and a photonic crystal fiber. Thorough numerical simulations are performed to estimate the device performance for both cases. A proof-of-principle demonstration of the frequency translation is conducted with a commercial photonic crystal fiber. Finally, a quantum simulator, serving as a quantum node in satellite-assisted quantum networks, is designed in a silicon nitride nanophotonic platform with cesium atoms. The designed photonic structure tailors electromagnetic vacuum such that photon-mediated forces between atoms causes collective motions mediating site-selective SU(2) spin-spin interactions. A coherent spin-exchange rate between atoms and collective dissipation rate of atoms are precisely estimated via finite-element time domain simulations. Furthermore, two schemes of trapping atoms in the vicinity of the designed structure are studied with calculations of potential energies and phonon tunneling rates. Experimental progress toward realization of the proposed system is summarized. The presented research activities of designing, analyzing, and implementing devices demonstrates the readiness of satellite-assisted quantum networks. This work contributes to creating quantum channels by entanglements with interfaces of various quantum systems in line with a broader scope of establishing a global quantum internet and quantum space exploration

The LISA Three-Backlink experiment: ultra-stable optical bench construction and non-reciprocity investigation

The Laser Interferometer Space Antenna (LISA) will be a future gravitational wave observatory in space. It will consist of three spacecraft forming a triangular constellation using laser links. The angles of the constellation will change due to orbital dynamics and require a compensation mechanism in each spacecraft. For this purpose, they each house two independently movable optical benches that are optically connected with each other via the so-called Backlink to exchange the laser light between the benches. The Backlink’s non-reciprocity is described by the differential phase stability of its counter-propagating beams and requires a noise level below pm/√Hz in the LISA measurement band. The experimental study of such a Backlink is the topic of this thesis, by constructing and commissioning an experiment to investigate three different Backlink implementations; the Three-Backlink Experiment. The LISA requirement can only be tested if the experiment is also pm-stable, which is reached by using quasi-monolithic optical benches with optical components glued onto a glass-ceramic baseplate. The first part of the thesis describes the construction of the complex optical benches, which house in total eight interferometers and four fiber-couplings with entangled construction requirements. A beam measurement and alignment tool, the Calibrated Quadrant Singleton, is investigated and characterized as an essential tool for the construction process. Alignment strategies were developed for the demanding construction steps and are presented in a conceptual form, so they are applicable in future optical bench constructions. The construction of the two benches is successfully completed. They are characterized for their relevant performance parameters and implemented in their experimental infrastructure. The second part of this thesis focuses on the Three-Backlink Experiment’s commissioning and noise analysis. The three different Backlink implementations enable a distinction of their individual noise couplings and contributions. The parameter of interest in the Backlink’s measurement is the nonreciprocity which reaches the requirement of 1pm/√Hz in the frequencies above 0.3 Hz for two Backlink implementations; the direct fiber implementation and the free-beam Backlink. Technical limitations in the current phase read-out measurement system limit the third Backlink implementation, the frequency-separated fiber Backlink. Backscatter at the direct fiber Backlink implementation enables the coupling of laser frequency noise and temperature to the non-reciprocity measurements. The observed couplings probe existing models and agree with their predicted noise coupling via Backlink backscatter. A free-beam connection between the two stationary optical benches is established with a closed piezo-mirror control loop that ensures pm-stability above 0.3 Hz. An upper limit for the performance of all three Backlinks is measured; the non-reciprocity is at 1.7pm/√Hz above 0.3 Hz, below 10pm/√Hz above 0.01 Hz, and at the frequencies below at 3pm/√Hz. At the current state, without motion between the optical benches, the free-beam implementation is operating with the lowest non-reciprocity noise contribution. The Three-Backlink Experiment offers a unique LISA-like test-bed on two optical benches enabling the study of coupling of different noises in the individual Backlink implementations. This thesis provides the key part of the test-bed, the optical benches, verifies the concept of the three Backlink’s disentanglement, and includes an analysis and modeling of its limiting noise sources

Testing foundations of quantum mechanics with photons

The foundational ideas of quantum mechanics continue to give rise to counterintuitive theories and physical effects that are in conflict with a classical description of Nature. Experiments with light at the single photon level have historically been at the forefront of tests of fundamental quantum theory and new developments in photonics engineering continue to enable new experiments. Here we review recent photonic experiments to test two foundational themes in quantum mechanics: wave-particle duality, central to recent complementarity and delayed-choice experiments; and Bell nonlocality where recent theoretical and technological advances have allowed all controversial loopholes to be separately addressed in different photonics experiments.Comment: 10 pages, 5 figures, published as a Nature Physics Insight review articl

Light pulse atom interferometry at short interrogation times for inertial navigation

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, February 2012."February 2012." Cataloged from PDF version of thesis.Includes bibliographical references (p. 141-150).Light pulse atom interferometry with cold atoms is a promising inertial sensing technology for high accuracy navigation. At present, laboratory atom interferometers match or surpass state of the art mechanical and optical inertial sensors in terms of sensitivity and long term stability. Conventional laboratory systems, however, do not achieve sufficient bandwidth or dynamic range to operate in a dynamic environment; furthermore, the size, weight and power of laboratory sensors are unsuitable for many applications. In this thesis, atom interferometry is realized at shorter interrogation times (100 ms), in which the required sensitivity, bandwidth and dynamic range of navigation systems becomes feasible. A cold atom gravimeter testbed using atom interferometry with stimulated Raman transitions was developed, which executed the entire measurement cycle in a compact vacuum cell (~ ~ 80 cc). The system demonstrated an inferred sensitivity of 2 [mu]g[square root] Hz for an interrogation time of 2T = 10 ms (based on measured phase SNR, scale factor, and repetition rate). With realistic improvements to the apparatus, it could achieve a sensitivity of <1 [mu]g[square root]Hz, advancing toward the realization of a compact, atom-based inertial measurement unit with unprecedented performance. In addition, a method for increasing the momentum splitting of Raman pulse interferometers with sequential Raman pulses was demonstrated, and interferometer area was increased by up to a factor of nine without altering the interrogation time (corresponding to a momentum splitting of 18hk, the largest reported for Raman pulse interferometry). Composite Raman pulses were implemented to improve population transfer efficiency, which limits the achievable increase in precision. Finally, the effect of coherent population trapping (CPT) induced by Raman pulse atom optics was identified as a source of systematic phase shifts in the [pi]/2 - [pi] - [pi]/2 interferometer used for sensing acceleration and rotation. CPT effects were modeled in a three-level (A) atom, and were experimentally characterized using atom interferometry. Based on the magnitude of measured coherences induced by Raman pulse atom optics, phase shifts of several milliradians should occur for a typical GHz-scale laser detuning. A method for suppressing this bias in realistic operation by Raman beam propagation direction reversal is proposed.by David L. Butts.Ph.D

Active compensation of extrinsic polarization errors using adaptive optics

We present a scheme for active compensation of complex extrinsic polarization perturbations introduced into an optical system. Imaging polarimeter is used to measure the polarization state across a beam profile and a liquid crystal spatial light modulator controls the polarization of the input beam. A sequence of measurements permits determination of the birefringence properties of a perturbing specimen. The necessary correction is calculated and fed back to the polarization modulator to compensate for the polarization perturbation. The system capabilities are demonstrated on a range of birefringent specimens