GaAs/GaAlAs heterostructure rib waveguide stepped [Triangle Open]β coupler

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Ultra-low noise lasers are essential tools in various applications, including data communication, light detection and ranging (LiDAR), quantum computing and sensing, and optical metrology. Recent advances in integrated photonics, specifically the development of the ultra-low loss silicon nitride (

Si3N4

) platform, have allowed attaining performance that exceeds conventional legacy laser systems, including the phase noise of fiber lasers. This platform can be combined with the monolithic integration of piez

This thesis explores the deposition of aluminium scandium nitride (AlScN) thin films on quartz substrates for tuning forks. The study is motivated by the superior piezoelectric properties of AlScN compared to tradition quartz tuning forks. Specifically, this research aims to take advantage of the high electromechanical coupling that AlScN demonstrates to improve the power efficiency of quartz tuning forks. The research methodology involves both analytical modeling and finite element simulations to compare

Microstereolithography is a 3D microfabrication technology that is fundamentally different from the techniques commonly used in cleanroom environment for the manufacturing of MEMS components. Most microfabrication techniques evolved from the microelectronics industry and often use silicon wafers as substrate or carrier material, thin films of metals deposited by evaporation or sputtering, thin layers of polymers deposited by spin coating and patterned by photolithography, chemical and plasma etching to gene

For truck and electric two-wheel applications, the design target is an electric motor with working point in the range of 18-20Nm @ 4000rpm functioning at ambient temperatures from -40°C to 105°C. The design will be based on an existing Sonceboz BLDC motor. The objective of this master project is to design an external rotor BLDC motor with integrated electronics for 48V onboard power supply with given design constraints: 1) Definition of the motor structure and design optimization (electromagnetic simulation

The selection of an hybrid MSF/RO desalination plant depends on many factors, such as capital costs, electricity consumption, water conversion rate and local requirements. In order to provide the necessary information for the decision process, stand-alone reverse osmosis or multi-stage °ash designs and alternative hybrid con¯gurations must be characterized, optimized and compared on a sound basis. The aim of this paper is to present a computer- aided method, for the design and optimization of hybrid desalin

This publication presents the application of Non-Linear Programming (NLP) to the design of AC induction motors driving hydraulic pumps on commercial aircrafts. In addition to the usual constraints on the geometry or on the efficiency of the motor, the specifications for this application include conditions on the supply frequency, environment temperature and in-rush current, which are very difficult to meet. The NLP had to be adapted to support constraints on multiple operating points of the motor. A prototy

The use of shadow masks (stencils) for nanopatterning overcomes the limitations typically present by patterning methods involving conventional optical lithography and etching, such as diffraction limit and etch selectivity. Nanostencils allow for resistless, low-cost nanopatterning on arbitrary surfaces in a single process step with the prospect of large-scale manufacturing. This paper presents the fabrication of metal cantilevers with sub-micron dimensions using direct evaporation through nanostencils, fol

Multi-hydrogenated compounds detection based on photoacoustic (PA) spectroscopy is reported. Three near-infrared semiconductor lasers are used with a resonant PA cell operated in its first longitudinal mode to monitor methane, water vapour and hydrogen chloride in the parts per million range. The design of our cell results from simulations performed in order to optimise its performances. Influence of the buffer gas on the PA signal has also been analysed, both theoretically and experimentally. A reduction o

Two of the most basic problems encountered in numerical optimization are least-squares problems and systems of nonlinear equations. The use of more and more complex simulation tools on high performance computers requires solving problems involving an increasingly large number of variables. The main thrust of this thesis the design of new algorithmic methods for solving large-scale instances of these two problems. Although they are relevant in many different applications, we concentrate specifically on real

Interplay between Identiﬁcation and Optimization in Run-to-run Schemes B. Srinivasan, D. Bonvin ´ Institut d’Automatique, Ecole Polytechnique F´d´rale de Lausanne, ee CH-1015 Lausanne, Switzerland. Optimization of batch processes has received increasing attention since its provides an uniﬁed framework to improve productivity without violating constraints on safety, selectivity, reproducability, etc. Due to uncertainties (disturbances and modeling errors) that are invariably present at the industrial level,

We demonstrate edge-emitting lasers based on self-assembled InAs quantum dots (QDs) on GaAs substrates. The InAs QDs are embedded in an InGaAs quantum well (QW) to red-shift the lasing transition. The lasers emit at lambda=1.2 mum with threshold current densities approximate to100 A/cm(2). Maximum modal gains on the order of 5 cm(-1) are deduced for a single QD sheet.

One of the intrinsic difficulties for in situ photoemission studies of high T-c oxide films is the surface volatility, especially the oxygen loss. In order to solve this problem, we have constructed a dedicated system for high T-c film surface studies, in particular for ARPES measurements. Here we briefly describe our pulsed laser deposition (PLD) system that is linked to the photoemission chamber at the Synchrotron Radiation Center (SRC) in Wisconsin, and discuss crystallographic and electronic properties

By using chemical beam epitaxy at growth temperatures as low as 460-480 degrees C, we have overcome strain relaxation problems that prevented so far the successful use of InAsP quantum wells in 1.55 mu m lasers. Five quantum well InAsP/InGaAsP horizontal cavity lasers showed 88% internal efficiency, 1.6 cm(-1) losses per well, and 33 A/cm(2) transparency current density per well, which equal or even surpass the best published characteristics for 1.55 mu m wavelength lasers based on any material system. More

Among all non-linear optical effects observed in single-mode optical fibres, stimulated Brillouin scattering (SBS) is of particular importance since it has numerous practical implications. SBS occurs when laser waves are scattered through the interaction of light with hypersonic acoustic waves in the medium. It manifests through the generation of a backscattered Stokes wave that carries most of the input optical power once a definite intensity level is reached within the fibre core. It limits the maximum op

GaAs/GaAlAs heterostructure rib waveguide stepped [Triangle Open]β coupler

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Monolithic piezoelectrically tunable hybrid integrated laser with sub-fiber laser coherence

AlScN Thin Film Deposition on Quartz for Power Efficient Tuning Forks

Microstereolithography

Design of an external BLDC motor with integrated electronics for 48V on-board power supply

Innovative design and multi-objective optimization of hybrid reverse osmosis and multi-stage flash desalination plants

Design optimization of induction motors for aerospace applications

Resistless Fabrication and Characterisation of Metal Nanolevers Arrays

Multi-gas sensing based on photoacoustic spectroscopy using tunable laser diodes

New algorithmic methods for real-time transportation problems

Interplay between Identification and Optimization in Run-to-run Schemes

Long-wavelength edge-emitting lasers on gallium arsenide using InAs quantum dots embedded in InGaAs

Surface optimization of RBa2Cu3O7-delta (R = Y, Nd) epitaxial high T-c films for in situ photoemission studies

Low Threshold 1.55 µm Wavelength InAsP/InGaAsP Strained Multi-Quantum Well Laser Diode Grown by Chemical Beam Epitaxy

La diffusion Brillouin dans les fibres optiques : étude et application aux capteurs distribués

GaAs/GaAlAs heterostructure rib waveguide stepped [Triangle Open]&beta; coupler

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GaAs/GaAlAs heterostructure rib waveguide stepped [Triangle Open]β coupler