Lithium Niobate Optical Waveguides and Microwaveguides

Lithium niobate has attracted much attention since the 1970s due to its capacity to modify the light by means of an electric control. In this chapter, we review the evolution of electro-optical (EO) lithium niobate waveguides throughout the years, from Ti-indiffused waveguides to photonic crystals. The race toward ever smaller EO components with ever-lower optical losses and power consumption has stimulated numerous studies, the challenge consisting of strongly confining the light while preserving low losses. We show how waveguides have evolved toward ridges or thin film-based microguides to increase the EO efficiency and reduce the driving voltage. In particular, a focus is made on an easy-to-implement technique using a circular precision saw to produce thin ridge waveguides or suspended membranes with low losses

Photo-Robotic Positioning for Integrated Optics

International audienceHigh positioning accuracy is a crucial need to perform successfully complex tasks such as micromanipulation and microassembly. This especially enables to provide high performances or to propose new functionalities/products, notably for integrated optical devices. The objective of the letter is to align two optical structures in multi-DOF way with very high accuracy. The originality of the approach relies on robotic positioning associated with the use of interfered reflected light irradiance as a feedback signal rather than transmitted power. Fabry–Perot interference principle is especially used to provide a fast and high accurate measurement. An opto-mechanical model that relates the optical component poses with the interfered reflected light is proposed. Experimental results are investigated based on a robotic multi-DOF platform, used to relatively align an optical component to an optical fiber. The obtained results establish that the model fits with experiments with a standard deviation below 0.0281∘. This model associated with an automated positioning strategy shows that it is possible to maximize reflectivity within less than 6 s, including multi-DOF angular misalignments identification and compensation

Superscaling variable and neutrino energy reconstruction from theoretical predictions to experimental limitations

We introduce the novel approach of using the superscaling variable as an observable and an analysis tool in the context of charged current neutrino-nucleus interactions. We study the relation between the superscaling variable and the removal energy, in addition to other fundamental parameters of the neutrino-nucleus interaction models. In the second half of the paper, we discuss the experimental viability of this measurement following a study of neutrino energy and missing momentum reconstruction. We show that the superscaling variable is measurable in neutrino interaction experiments provided that the proton is detected in the final state. We discuss the resolution of this measurement, and the limitation imposed by the proton’s detection threshold

Free-standing LiNbO3 micro and nanosystems fabricated by precise dicing

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Etude pédagogique de modulateurs électro-optiques pour l'infrarouge moyen

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Belgique

Study of the assumptions to obtain a technologically and economically viable decarbonised ammonia and steelmaking plant

Lithium Niobate micro-nano patterning for Integrated Optics, Photonics and Acoustics

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Autoencoder as a New Method for Maintaining Data Privacy While Analyzing Videos of Patients With Motor Dysfunction: Proof-of-Concept Study.

BACKGROUND In chronic neurological diseases, especially in multiple sclerosis (MS), clinical assessment of motor dysfunction is crucial to monitor the disease in patients. Traditional scales are not sensitive enough to detect slight changes. Video recordings of patient performance are more accurate and increase the reliability of severity ratings. When these recordings are automated, quantitative disability assessments by machine learning algorithms can be created. Creation of these algorithms involves non-health care professionals, which is a challenge for maintaining data privacy. However, autoencoders can address this issue. OBJECTIVE The aim of this proof-of-concept study was to test whether coded frame vectors of autoencoders contain relevant information for analyzing videos of the motor performance of patients with MS. METHODS In this study, 20 pre-rated videos of patients performing the finger-to-nose test were recorded. An autoencoder created encoded frame vectors from the original videos and decoded the videos again. The original and decoded videos were shown to 10 neurologists at an academic MS center in Basel, Switzerland. The neurologists tested whether the 200 videos were human-readable after decoding and rated the severity grade of each original and decoded video according to the Neurostatus-Expanded Disability Status Scale definitions of limb ataxia. Furthermore, the neurologists tested whether ratings were equivalent between the original and decoded videos. RESULTS In total, 172 of 200 (86.0%) videos were of sufficient quality to be ratable. The intrarater agreement between the original and decoded videos was 0.317 (Cohen weighted kappa). The average difference in the ratings between the original and decoded videos was 0.26, in which the original videos were rated as more severe. The interrater agreement between the original videos was 0.459 and that between the decoded videos was 0.302. The agreement was higher when no deficits or very severe deficits were present. CONCLUSIONS The vast majority of videos (172/200, 86.0%) decoded by the autoencoder contained clinically relevant information and had fair intrarater agreement with the original videos. Autoencoders are a potential method for enabling the use of patient videos while preserving data privacy, especially when non-health-care professionals are involved

Optical-Coherence-Tomography characterization of free standing electro-optical micro and nanostructures

International audienceThin-film-based LiNbO 3 components have been experiencing an increasing success over the past decade due to their potentiality to enhance electro-optical (EO) or nonlinear (NL) effects [1, 2]. Therefore, their production at low cost is becoming a major challenge. In [3, 4], we proposed a precise-dicing-based technique for the low-cost production of confined LiNbO 3 waveguides with integrated spot-size-converters, and we achieved a four-time reduction of the driving power while keeping insertion losses lower than 3 dB. Here we go one step further by proposing free-standing electro-optical micro and nanostructures in sub-micrometer-thin layers of LiNbO 3 . We also employ an optical-coherence-tomography (OCT)-based characterization method to evaluate the birefringence, group velocity, propagation losses, and electro-optical sensitivity of the membranes

Photo-robotic positioning of quaterwaveplates for integrated optics

International audienceHigh positioning accuracy is a crucial need to perform successfully complex tasks such as micromanipulation and microassembly. This especially enables to provide high performances or to propose new functionalities/products, notably for integrated optical devices. The objective of the letter is to align two optical structures in multi-DOF way with very high accuracy. The originality of the approach relies on robotic positioning associated with the use of interfered reflected light irradiance as a feedback signal rather than transmitted power. Fabry–Perot interference principle is especially used to provide a fast and high accurate measurement. An opto-mechanical model that relates the optical component poses with the interfered reflected light is proposed. Experimental results are investigated based on a robotic multi-DOF platform, used to relatively align an optical component to an optical fiber. The obtained results establish that the model fits with experiments with a standard deviation below 0.0281◦. This model associated with an automated positioning strategy shows that it is possible to maximize reflectivity within less than 6 s, including multi-DOF angular misalignments identification and compensation