Ce mémoire présente les résultats de travaux portant sur l’analyse de la fiabilité de diodes laser de pompe émettant à 980 nm et de photodiodes InGaAs pour des applications spatiales. La sévérité de l’environnement spatial (vide, radiations, contraintes thermomécaniques) impose d’évaluer la robustesse de ces deux technologies qui ont été spécialement conçues pour des applications de télécommunications sous-marines. L’objectif de ce mémoire est donc de proposer une méthodologie d’évaluation de la fiabilité en s’appuyant la caractérisation électro-optique, l’analyse physico-chimique et la modélisation. Les diodes laser ont été vieillies sous ultravide (pression de 10-7 mbar) pendant 5000h sous 800 mA et 60°C. Certains composants, dont l’herméticité du boîtier a été volontairement rompue, ont présenté des défaillances de type COD (Catastrophic Optical Damage). Les caractéristiques des composants, dont le boîtier est resté hermétique, n’ont cependant pas dérivé. Après avoir modélisé les caractéristiques électriques du composant, mené des analyses physiques (AFM, MEB, MET, cathodoluminescence et ToF-SIMS) et calculé la variation de la pression à l’intérieur du boîtier, nous avons estimé la durée de vie du composant fonctionnant sous ultravide à 26 ans.Les photodiodes ont été irradiées par des protons d’énergie comprise entre 30 et 190 MeV sous une fluence comprise entre 5.1010 et 1012 p/cm², entrainant une augmentation du courant d’obscurité de trois décades. La modélisation du courant d’obscurité a permis d’estimer la durée de vie du composant en environnement spatial à 15 ans.Ces travaux ont également contribué à mettre en évidence des mécanismes de dégradation peu documentés (COD sous vide, difficulté d’ajustement avec le NIEL, dégradation du réseau de Bragg exposé aux rayonnements ionisants), ce qui permet de mieux appréhender le comportement des diodes laser et des photodiodes exposées à l’environnement spatial. / In this work, the reliability of 980 nm pump laser diode and InGaAs photodiode modules has been estimated for space applications. The space environment is particularly harsh (vacuum, radiation, thermal and mechanical stresses) for these electro-optical devices, which were designed for long-haul submerged telecommunication applications. The main objective of this thesis is to provide a guideline for the space evaluation of optoelectronic devices, using characterization, physical analysis and modeling.Eight laser diodes were aged in vacuum (10-7 mbar) during 5000h, at 60°C and 800 mA bias current. The hermeticity of four of them was voluntarily broken to simulate a long term vacuum exposition. Three of four non-hermetic devices failed during the ageing, because of COD (Catastrophic Optical Damage) whereas the electro-optical characteristics of hermetic devices remained unchanged. The MTBF of laser diodes operating in vacuum was estimated to 26 years, by means of modeling (electro-optics and pressure) and physical analyses (AFM, SEM, TEM, cathodoluminescence, ToF-SIMS).InGaAs photodiodes were irradiated by protons, with energies ranging from 30 to 190 MeV and fluences ranging from 5.1010 to 1012 p/cm². The dark current increased by three decades after irradiation. The photodiode MTBF was then estimating to 15 years using dark current modeling.This study also permitted to show up almost new failure mechanisms (COD under vacuum, NIEL scaling errors in InGaAs, Bragg grating degradation under ionizing radiation and its effects on laser diode stabilization), which could contribute to the space evaluation of laser diodes and photodiodes for future missions.

The past decade witnessed the rapid development of III-nitride light-emitting diodes (LEDs) and laser diodes (LDs), for smart lighting, visible-light communication (VLC), optical storage, and internet-of-things. Recent studies suggested that the GaN-based LDs, which is free from efficiency droop, outperform LEDs as a viable high-power light source. Conventionally, the InGaN-based LDs are grown on polar, c-plane GaN substrates. However, a relatively low differential gain limited the device performance due to a significant polarization field in the active region. Therefore, the LDs grown on nonpolar m-plane and semipolar (2021)-plane GaN substrates are posed to deliver high-efficiency owing to the entirely or partially eliminated polarization field. To date, the smart lighting and VLC functionalities have been demonstrated based on discrete devices, such as LDs, transverse-transmission modulators, and waveguide photodetectors. The integration of III-nitride photonic components, including the light emitter, modulator, absorber, amplifier, and photodetector, towards the realization of III-nitride photonic integrated circuit (PIC) offers the advantages of small-footprint, high-speed, and low power consumption, which has yet to be investigated. This dissertation presents the design, fabrication, and characterization of the multi-section InGaN laser diodes with integrated functionalities on semipolar (2021)-plane GaN substrates for enabling such photonic integration. The blue-emitting integrated waveguide modulator-laser diode (IWM-LD) exhibits a high modulation efficiency of 2.68 dB/V. A large extinction ratio of 11.3 dB is measured in the violet-emitting IWM-LD. Utilizing an integrated absorber, a high optical power (250mW), droop-free, speckle-free, and large modulation bandwidth (560MHz) blue-emitting superluminescent diode is reported. An integrated short-wavelength semiconductor optical amplifier with the laser diode at ~404 nm is demonstrated with a large gain of 5.32 dB at 6 V. A high-performance waveguide photodetector integrated LD at 405 nm sharing the single active region is presented, showing a significant large modulation bandwidth of 230 MHz. Thus these seamlessly integrated elements enable photonic IC at the visible wavelength for many important applications, such as smart lighting and display, optical communication, switching, clocking, and interconnect. The findings are therefore significant in developing an energy-saving platform technology that powers up human activities in a safe, health- and environmental-friendly manner.

This thesis deals with the design and subsequent realization of laser diode control devices. The circuit will be able to control the diode with using a laser driver, via a computer network or via the display for control current values, setting of initial values and more. The device will be connected also with a SD card for saving of settings. In the theoretical part there are described individual components that are needed for functionality of the device. The practical part contains a block diagram, in which is described complete feature of the device, then a draft scheme with a description of all integrated circuits and important components. At the end of this work is described the software that controls the entire designed device.

The subject of this thesis is the construction of one-way communication device. This device consists of the transmitter and the receiver, both of which are connected to its respective computer via USB interface. This device allows sending UTF-8 characters or files from one computer to another. Both computers are running a graphical user interface program. The core of a transmitter is a digital signal modulating laser diode. The receiver is made of photovoltaic panel with a resonance circuit and an amplifier. Communication between the electronics and the computer is driven by microcontrollers. Received messages are verified with one of multiple error detection algorithms, which can be selected by user in the utility program.

This project is about design of contactless measuring ventilator - revolution counter. The counter serves to measurement of the speed of ventilator. The measurement is based on optical method of receiving the reflected laser beam. To measure and calculate use the revolution counter the microcontroller. This measured value is diplayed on LCD. After design follows experimental measurement.

La capacité des sources laser à concentrer une quantité d’énergie énorme intéresse beaucoup le secteur industriel pour l’usinage et la structuration de la matière. Il faut pour cela rassembler une forte puissance optique sur une surface infime: on parle alors de luminance. La combinaison cohérente permet de répondre à la problématique de l’augmentation de la luminance d’un système laser. Dans le cadre du projet européen BRIDLE, ces travaux sont focalisés sur la combinaison cohérente de lasers à semi-conducteur. Ce type de combinaison nécessite un accord de phase stable entre les différents émetteurs. Plusieurs techniques permettent cette mise en phase; nous étudions en particulier les techniques d’amplification en parallèle ainsi que l’utilisation d’une cavité externe commune. L’originalité se situe dans le développement d’une architecture nouvelle, pensée pour optimiser l’extraction de puissance. La technique consiste à utiliser une cavité étendue commune aux émetteurs à combiner pour leur mise en phase, placée sur leur face arrière. Tout en fournissant un fort retour optique arrière nécessaire à la mise en phase, l’extraction de puissance est maximisée sur la face avant où les faisceaux sont par la suite combinés extracavité. Ce document démontre la bonne adéquation de cette architecture avec les meilleures diodes laser en termes de luminance : les émetteurs à section évasée. L’étude est étendue à une barrette de diodes par l’utilisation d’éléments diffractifs optique permettant la séparation et la combinaison des faisceaux. / Scaling up the brightness of laser diodes is a major research objective in the laser community. The coherent beam of several emitters is the most efficient technique to increase the brightness by constructive interference. An efficient combination can only be achieved in an arrangement that forces the required phase relation between the emitters. Different approaches are investigated: either active phase-locking of amplifiers seeded by a single-frequency laser split into N beams and amplified in parallel, or passive selforganization of emitters in a common laser cavity. We investigate a new coherent combining architecture using a common extended cavity on the back side of diode lasers for phase locking. As a result, the efficiency of the phase-locked laser cavity is increased as compared to standard front-side configurations. Moreover, such an extended cavity placed on the rear-side provides the strong optical feedback required for phase-locked operation. This configuration is demonstrated with high-brightness tapered devices, highlighting the capability of such setup for high power operation. This architecture is then extended to diode laser arrays by the use of diffractive optical elements.

Interferometric optical fiber sensors have proved many orders of magnitude more sensitive than their electrical counterparts, but they suffer from limitations in signal demodulation caused by phase ambiguity and complex fringe counting when the output phase difference exceeds one fringe period. Various signal demodulation methods have been developed to overcome some of the these drawbacks with limited success. This thesis proposes a new measurement system for the extrinsic Fabry-Perot interferometer (EFPI) sensor. Using a wavelength modulated source and a novel extended-gap EFPI, some of the limitations of interferometric signal demodulation are overcome. By scanning the output wavelength of a multilongitudinal mode laser diode through current modulation, the EFPI sensor signal is scanned through multiple fringes. Gap movement is then unambiguously determined by monitoring the phase of the multiple fringe pattern. / Master of Science

Ces travaux de thèse ont pour objectif de proposer une nouvelle technique de caractérisation électro-optique de barrettes de diodes Laser de puissance (DLPs), au niveau émetteur individuel à partir d'un banc dédié, utilisées pour le pompage optique à 808nm de système LIDAR en environnement spatial et en régime QCW. Après une étude métrologique fine, ils décrivent une méthodologie de sélection d'un indicateur précoce de défaillance potentielle et sa capacité à estimer la fiabilité de DLPs en conditions opérationnelles (> 109 impulsions à 100Hz/200µs). L’analyse de la dégradation des DLPs se base sur l'identification de signatures paramétriques de défaillance mises en lumière après une série de tests accélérés ciblés et relatives à l'évolution de la puissance optique, du spectre optique (λmax) et du degré de polarisation (DOP) de chaque émetteur de la barrette. Nous montrons également la forte complémentarité entre la mesure du DOP par électroluminescence et par photoluminescence et nous proposons une méthodologie de sélection précoce des émetteurs en considérant leur localisation dans le plan (λmax, DOP). Ces études expérimentales, confortées par des simulations thermiques et mécaniques par éléments finis en introduisant un grand nombre de paramètres technologiques, ont permis de quantifier les niveaux de contraintes résiduelles dans les DLPs en fonction de différentes configurations d'assemblage et d'établir un lien avec leur fiabilité intrinsèque. / This thesis work aimed to propose a new methodology for electro-optical characterization ofQCW laser diodes array (LDA) at emitter level by using a dedicated test bench. After detailedmetrological study, a methodology for selecting an early failure indicator and its ability to assess theLDA reliability in operational conditions (> 109 Shots at 100Hz/200μs) has been described. The LDAdegradation analysis were based on identification of parametric failure signatures highlighted after aset of accelerated tests and have been focused on the evolution of optical power, optical spectrum(λmax) and the degree of polarization (DOP) of each emitter on the LDA. We also explain the strongcomplementarity between the measured DOP of photoluminescence and the DOP ofelectroluminescence and a methodology for early selection of emitters have been proposed by takinginto account their location in the plane (λmax, DOP). These experimental studies were comforted bythermal and mechanical finite element simulations, by introducing several technological parameters inorder to quantify levels of induced mechanical stresses in LDA under different assemblyconfigurations and to establish the link with their intrinsic reliability.

No description available.

A relatively new application for the laser is in fluorescence microscopes. The fluo- rescence microscope needs a high power light source input. Using a laser source improves the precision of the microscope. A pulsed laser source enhances the performance of the fluorescence microscope and a laser diode can be overdriven without being damaged. The thesis investigates which properties of the laser pulses are needed regarding pulse width, pulse period and waveform. The thesis also investigates which properties are desired for the electrical pulses driving the laser, and how they can be generated using electrical components. The desired laser pulse should have a pulse width of 100 ps and a pulse period of 50 ns. The laser pulse should also have a well-defined wavelength, stable output power and it should be able to quickly turn on and off. To achieve this laser pulse, the desired input to the laser diode should have an input voltage of 5 V, an input current of 250 mA, a pulse width of 100 ps and a pulse period of 50 ns. For generating this pulse the chosen pulse generator, an SRD, should have low junction capacitance, low package capacitance and low package inductance. The chosen amplifier, a MESFET, desires low drain current and should have high transconductance and a large negative threshold voltage.