Search results for "PASS"
showing 10 items of 1629 documents
Galerkin Scheme-Based Determination of Survival Probability of Oscillators With Fractional Derivative Elements
2016
In this paper, an approximate semi-analytical approach is developed for determining the first-passage probability of randomly excited linear and lightly nonlinear oscillators endowed with fractional derivative elements. The amplitude of the system response is modeled as one-dimensional Markovian process by employing a combination of the stochastic averaging and the statistical linearization techniques. This leads to a backward Kolmogorov equation which governs the evolution of the survival probability of the oscillator. Next, an approximate solution of this equation is sought by resorting to a Galerkin scheme. Specifically, a convenient set of confluent hypergeometric functions, related to …
Optimization of semiconductor halide perovskite layers to implement waveguide amplifiers
2017
Semiconductor organometallic halide (CH 3 NH 3 PbX 3 , X=Cl, Br, I) perovskites (HPVK) have been emerged as a potential gain media to construct a new generation of active photonic devices. Indeed, during the last three years a significant effort has been carried out to implement HPVK-based optical amplifiers or lasers with improved quality factors. In particular, minimization of the threshold of stimulated emission has been an important concern to decrease the power consumption, and hence to enhance the performances of the device. For this purpose strategies include a suitable integration of the semiconductor in a photonic structure, or the optimization of the material. Here we propose a no…
Enhancement of the Performance of Perovskite Solar Cells, LEDs, and Optical Amplifiers by Anti-Solvent Additive Deposition
2016
The efficiency of perovskite optoelectronic devices is increased by a novel method; its suitability for perovskite solar cells, light-emitting diodes, and optical amplifiers is demonstrated. The method is based on the introduction of organic additives during the anti-solvent step in the perovskite thin-film deposition process. Additives passivate grain boundaries reducing non-radiative recombination. The method can be easily extended to other additives.
Q switching and mode locking pulse generation from an all-fiber ring laser by intermodal acousto-optic bandpass modulation
2018
Q-switched and mode-locked (QML) pulse generation from an all-fiber ring laser based on intermodal acousto-optic bandpass modulation is reported. The modulator relies on full-acousto-optic mode re-coupling cycle induced by a standing flexural acoustic wave, with a transmission response that is controlled by amplitude modulation of the acoustic wave signal. The Q factor of the cavity is controlled by a rectangular pulse wave with variable frequency and duty cycle, whereas mode locking is achieved by amplitude modulation derived from a standing flexural acoustic wave. The best QML pulses were obtained at 0.5 kHz repetition rate, with a pump power of 549.2 mW, at the optical wavelength of 1568…
Experimental study of an in-fiber acousto-optic tunable bandpass filter for single- and dual-wavelength operation in a thulium-doped fiber laser
2019
A tunable single- and dual-wavelength thulium-doped all-fiber laser is demonstrated based on the implementation of an in-fiber acousto-optic tunable bandpass filter (AOTBF). The AOTBF is fabricated to be operated in the 1.9 µm region, and takes advantage of the intermodal coupling effect produced by traveling flexural acoustic waves in an optical fiber. It exhibits a 3-dB bandwidth of 2.04 nm with an insertion loss of 4.75 dB. The tuning properties of the AO device allows a continuous-wave operation with characteristics of wide tuning range (211.5 nm), narrow linewidth (50 pm) and high signal-to-noise ratio (60 dB). In the dual-wavelength regime, the laser is capable of independent tuning o…
Design of a continuously tunable delay line using vectorial modulational instability and chromatic dispersion in optical fibers
2009
International audience; We design an all-optical tunable delay line based on both dispersive and wavelength conversion stages involving modulational instability of a two-frequency pump field propagating in a highly birefringent fiber. More precisely, we numerically show that, by varying the frequency separation between the two orthogonally polarized pump waves, we achieve a controllable and continuous delay of hundreds of picoseconds for signal pulse durations from picoseconds to nanoseconds, without pulse distortion and with only small peak power fluctuations. The proposed method does not require any tunable bandpass filter and can be applied to delay digital data streams at tens of Gbit/s…
Spectral Slicing of a Supercontinuum Source for WDM/DS-OCDMA Application
2008
WDM and optical CDMA are leading contenders to easily upgrade access network performances in terms of multiple access technique. Both methods can be used at once, using a single multiwavelength optical source. We show, numerically and experimentally, that spectral slicing of a 10-GHz pulse train broadened to a supercontinuum yields pulses suitable for use in a direct sequence optical CDMA system. Simulations with optical CDMA encoders and decoders based on superstructured fiber Bragg gratings indicate good performance can be expected.
Remote photoplethysmography for skin perfusion monitoring using narrowband illumination
2019
The purpose of this study was to determine potential of remote photoplethysmography for skin perfusion monitoring, using 540 nm narrowband and 530 nm broadband illuminations. The alterations of cutaneous circulation were produced by topical skin heating protocol. The setup comprises of 530 nm LED light source and two identical cameras operated simultaneously: one equipped with narrowband optical filter (CWL=540nm), and another without filter. Results demonstrate the typical heating test response curve- comprising first peak, nadir and plato phase, which were significantly different in narrowband and broadband illumination. It was concluded that selection of optimal light source parameters i…
Earthquake Excited Base-Isolated Structures Protected by Tuned Liquid Column Dampers: Design Approach and Experimental Verification
2017
Abstract In this contribution a direct approach for optimal design of a Tuned Liquid Column Damper (TLCD) device attached to the base slab of a base-isolated structure is presented, aiming at reducing the seismic displacement demand of the base-isolation subsystem. Assuming white noise base excitation, for a wide parameter range a direct optimization procedure yields design charts for optimal TLCD quantities. The performance of the base-isolated structure equipped with optimally tuned TLCD device in comparison to the simple base-isolated one is evaluated both numerically and experimentally. In a numerical study the system is subjected to the 44 records of the FEMA P-695 far-field ground mot…
Hybrid Passive Control Strategies for Reducing the Displacements at the Base of Seismic Isolated Structures
2019
In this paper, the use of hybrid passive control strategies to mitigate the seismic response of a base-isolated structure is examined. The control performance of three different types of devices used for reducing base displacements of isolated buildings is investigated. Specifically, the Tuned Mass Damper (TMD), the New Tuned Mass Damper (New TMD) and the Tuned Liquid Column Damper (TLCD), each one associated to a Base Isolated structure (BI), have been considered. The seismic induced vibration control of base-isolated structures equipped with the TMD, New TMD or the TLCD is examined and compared with that of the base-isolated system without devices, using real recorded seismic signals as e…