Search results for " OPT"
showing 10 items of 13620 documents
An IPMSM torque/weight and torque/moment of inertia ratio optimization
2014
In this paper, a torque/weight and torque/moment of inertia ratio optimization procedure for interior permanent magnet syncronous motors (IPMSMs) is presented. More in detail, a performance comparison between several IPMSM rotor structures has been carried out in order to determine the optimum geometry that can maximize the torque/weight and torque/moment of inertia ratios. A commercial motor, with known electrical and mechanical characteristics, has been taken as reference. Its rotor structure has been modified several times, obtaining different rotor geometries and, therefore, many IPMSM models with different electrical and mechanical characteristics. The finite element method (FEM) analy…
Strain and temperature measurement discrimination with forward Brillouin scattering in optical fibers
2022
A novel method that enables simultaneous and discriminative measurement of strain and temperature using one single optical fiber is presented. The method is based on the properties of transverse acoustic mode resonances (TAMRs) of the optical fiber. In particular, it is based on the different sensitivity to temperature and strain that exhibit the radial modes R0,m and a family of torsional-radial modes denoted as T R 2 , m ( 1 ) . We show that the resonance frequencies of both types of resonances shift linearly with temperature and strain, but at different rates. By the combined use of the different sensitivities of the two families of TAMRs, we experimentally demonstrate discriminative mea…
Focus issue introduction: 3D image acquisition and display: technology, perception and applications.
2022
This Feature Issue of Optics Express is organized in conjunction with the 2021 Optica (OSA) conference on 3D Image Acquisition and Display: Technology, Perception and Applications which was held virtually from 19 to 23, July 2021 as part of the Imaging and Sensing Congress 2021. This Feature Issue presents 29 articles which cover the topics and scope of the 2021 3D conference. This Introduction provides a summary of these articles.
Experimental study of MMI structures in a switchable continuous-wave thulium-doped all-fiber laser
2022
Switchable multi-wavelength laser emission from a thulium-doped all-fiber laser is reported by implementing a tapered and a non-tapered multi-modal interference (MMI) filters. The MMI structure relies on a coreless optical fiber spliced in between two single-mode optical fibers. For the non-tapered case, a minimum insertion loss of 12.60 dB is achieved around the 2-μm region, from which stable generation of commutable dual-wavelength emission at 1986.34 nm and 2017.38 nm is obtained. On the other hand, the tapered MMI structure performs a minimum insertion loss of 8.74 dB at the 2-μm region, allowing a stable triple-wavelength emission at 1995.4 nm, 2013.3 nm, and 2038.3 nm. In addition, co…
Recent Advances in Forward Brillouin Scattering: Sensor Applications
2022
In-fiber opto-mechanics based on forward Brillouin scattering has received increasing attention because it enables sensing the surrounding of the optical fiber. Optical fiber transverse acoustic resonances are sensitive to both the inner properties of the optical fiber and the external medium. A particularly efficient pump and probe technique—assisted by a fiber grating—can be exploited for the development of point sensors of only a few centimeters in length. When measuring the acoustic resonances, this technique provides the narrowest reported linewidths and a signal-to-noise ratio better than 40 dB. The longitudinal and transverse acoustic velocities—normalized with the fiber radius—can b…
Narrowband Monolithic Perovskite-Perovskite Tandem Photodetectors
2022
Narrowband photodetectors (PDs) are sought after for many applications requiring selective spectral response. The most common systems combine optical bandpass filters with broadband photodiodes. This work reports a method to obtain a narrowband response in a perovskite PD by the monolithic integration of a perovskite photoconductor and a perovskite photodiode. The spectral response of the tandem PD is determined by the bandgap energy difference of the two perovskites, and exhibits a full width at half maximum below 85 nm, an external quantum efficiency up to 68% and a high specific detectivity of ≈1012 Jones in reverse bias, enabling the device to detect weak light signals. The absorption p…
Nonlinearity measurement undergoing dispersion and loss
2023
Accurate knowledge of the nonlinear coefficient is extremely important to make reliable predictions about optical pulses propagating along waveguides. Nevertheless, determining this parameter when dispersion and loss are as important as nonlinear effects brings both theoretical and experimental challenges that have not yet been solved. A general method for measuring the nonlinear coefficient of waveguides under these demanding conditions is here derived and demonstrated experimentally in a kilometer-long standard silica fiber pumped close to 2 µm.
Sentinel satelītdatu izmantošana kā alternatīva hlorofila-a in situ mērījumu veikšanai Rīgas līcī
2022
Hlorofila-a mērīšana un uzraudzīšana ir svarīga vides izmaiņu konstatēšanā un vides problēmu risināšanā Rīgas līcī. Attālinātā hlorofila-a mērīšana būtu efektīvāka par in situ paraugu ievākšanu, jo tiktu vienlaicīgi apsekota liela teritorija, ietaupīts laiks un resursi. Mūsdienu tālvadības sensoru, piemēram, OLCI (Okeāna un zemes krāsu instrumenta) uz Sentinel-3 satelīta ir ļāvusi iegūt okeāna bioģeoķīmiskos produktus ar augstāku telpisko (300 m x 300 m) izšķirtspēju, nekā tas bija iespējams agrāk. Taču galvenā problēma ir Baltijas jūras optiskās īpašības, kas sarežģī attālināto metožu algoritmu pielietošanu. Bakalaura darba mērķis ir novērtēt Sentinel satelītdatu produktu precizitāti Rīgas…
Активаторные и околоактиваторные возбуждения щелочно-галоидных кристаллов, активированных двухзарядными ртутеподобными ионами
1989
Advisor: Плявиня, Ирена
Dynamics of a harmonic oscillator coupled with a Glauber amplifier
2020
A system of a quantum harmonic oscillator bi-linearly coupled with a Glauber amplifier is analysed considering a time-dependent Hamiltonian model. The Hilbert space of this system may be exactly subdivided into invariant finite dimensional subspaces. Resorting to the Jordan-Schwinger map, the dynamical problem within each invariant subspace may be traced back to an effective SU(2) Hamiltonian model expressed in terms of spin variables only. This circumstance allows to analytically solve the dynamical problem and thus to study the exact dynamics of the oscillator-amplifier system under specific time-dependent scenarios. Peculiar physical effects are brought to light by comparing the dynamics…