Bimodal Resonance Phenomena. Part III: High-Contrast Grating Reflectors

The extraordinary broadband high-reflectivity features of high-contrast gratings are stimulating great interest in many opto-electronic applications. In view of obtaining a simple simulation framework, the analogy of high-contrast grating reflectors with bimodal Fabry-Pérot interferometers is proposed. The closed-form expressions of the interferometer reflectivity, obtained starting from a novel parametrization of the scattering matrices characterizing the bar-air interface, allow a complete exploration of the device parameter space, explaining and predicting the phenomenon of ultra-broadband quasi-100% reflectivity. In this paper an optimized and numerically efficient design procedure is described and compared with the standard rigorous coupled wave analysis, both for the classical "bar-in-air" configuration and for a more robust and practical one, with bars lying on a dielectric support. It is shown that the model can be applied also in the more realistic case of lossy gratings

Mastering Lateral Radiation Losses in Tunable VCSELs

This paper deals with the loss mechanisms in tunable vertical-cavity surface-emitting lasers (VCSELs). The strong increase of the threshold gain at the tuning range edges motivates the investigation of the degradation mechanisms presented in this paper. A campaign of simulations performed with our in-house VCSEL ELectroMagnetic (VELM) simulation code, combined with a novel approach based on the study of the Poynting vector, allowed to identify significant lateral radiation losses. The proposal of technology-affordable countermeasures rests on the proper understanding of these phenomena

Simulation of Spiral Phase Plate VCSELs

Several groups belonging to different scientific communities are focusing their efforts on the theoretical and applied research on the orbital angular momentum of light (OAM). Among the most significant examples in the field of ICT, the OAM-division multiplexing recently emerged as a viable approach for increasing the capacity of the next generation optical networks. Optical beams featuring an OAM are usually generated through the conversion of a standard laser mode; such techniques usually rely on bulk optical components such as computer-generated holograms, spatial light modulators or spiral phase plates (SPPs). In a recent paper Li et al. proposed the possibility to load a commercial GaAs VCSEL with a micro-SPP [1]. The resulting device, which can emit directly OAM modes, is extremely appealing in view of reducing manufacturing costs, even opening up the possibility to introduce it in mass market applications, with an eye to the “green technology” paradigm in which VCSELs perfectly fit, due to their well-known low consumption features. The experimental work described in [1] has been complemented by a theoretical study performed by means of our in-house Vcsel ELectroMagnetic simulator (VELM) [2]. The possibility to estimate the OAM mode efficiency with full-wave simulations allowed to perform a thorough analysis of the sensitivity of the device to the possible manufacturing issues. As an example of the several numerical results that will be presented during the conference, Fig. 1 shows the simulated field profiles for the unprocessed VCSEL and for three micro-SPP geometries producing various OAM orders. Furthermore, the flexibility of VELM opens up the possibility to explore alternative implementations of SPP-VCSELs. Such solutions, supported by a technological affordability study, may allow to further develop these devices, in view of improving the emitted OAM mode purity while lowering the manufacturing costs

Skew Incidence Plane-Wave Scattering From 2-D Dielectric Periodic Structures: Analysis by the Mortar-Element Method

A full-wave simulator of 2-D dielectric periodic structures under skew plane wave incidence is presented in this paper. A differential formulation is used and the boundary value problem is solved by means of a multi-domain spectral method. Suitable mappings allow the efficient analysis of dielectric elements with rounded corner cross sections. A comparison with the results obtained by the method of moments and with a commercial simulator is presented for an array of dielectric rods and for a surface-relief diffraction grating

La autoeficacia y desempeño competitivo en atleta de alto rendimiento. Caso Luis Alberto Orta Sánchez (Original)

This article is based on existing research demands in the field of Sport Psychology and its objective is to analyze the manifestation of perceived self-efficacy in the Cuban high-performance athlete of Greco-Roman Wrestling Luis Alberto Orta Sánchez of Greco-Roman Wrestling in the face of vital events. of his sports career. Research methods were used with a predominance of analytical qualitative methodology: the single case study, in which vital events of his sports career, analysis-synthesis, interviews, document analysis, experiential self-report and videos are referred. The main results allowed us to verify the presence of the category "very safe" (4), in its possibilities that represents a high level of strength and generality of perceived self-efficacy to face the vital events of its activity, specifically manifested in the combats developed. in their participation in the Tokyo 2020 Olympic Games. The main conclusions highlight the need to assess in high-performance athletes the study of the level of self-efficacy as an important motivational indicator, predictor of self-regulation of behavior expressed in volitional qualities and personality traits. personality related to coping with adversity in athletes that can be models and experiences to take into account in the work of psychological preparation of high-level athletes.El presente artículo se fundamenta en demandas de investigación existentes en el ámbito de la Psicología del Deporte y se plantea como objetivo analizar la manifestación de la autoeficacia percibida en el deportista de alto rendimiento cubano de Lucha grecorromana Luis Alberto Orta Sánchez de Lucha Grecorromana ante su participación en los Juegos Olímpicos Tokio 2020. Se utilizaron métodos de investigación con predominio de la metodología cualitativa analítica: el estudio de caso único, en el que se refieren eventos vitales de su trayectoria deportiva, análisis-síntesis, entrevistas, análisis de documentos, autoreporte vivencial y videos. Los resultados principales permitieron constatar la presencia de la categoría “muy seguro” (4), en sus posibilidades que representa un alto nivel de fuerza y generalidad de la autoeficacia percibida para enfrentarse a los eventos vitales de su actividad, específicamente manifestada en los combates desarrollados en su participación en los Juegos Olímpicos de Tokio 2020. Las conclusiones principales destacan la necesidad de valorar en los deportistas de alto rendimiento el estudio del nivel de autoeficacia como importante indicador motivacional, predictor de la autorregulación de la conducta expresadas en cualidades volitivas y rasgos de la personalidad relacionadas con el enfrentamiento a las adversidades en deportistas que pueden constituir modelos y experiencias a tener en cuenta en la labor de la preparación psicológica de los deportistas de alto nivel