scholarly journals Light-Induced Effects in Amorphous Chalcogenide Glasses: Femtoseconds to Seconds

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 255-274
Author(s):  
Pritam Khan ◽  
K. V. Adarsh
Keyword(s):  
Time Domain ◽  
Chalcogenide Glasses ◽  
Continuous Wave ◽  
Transient Absorption ◽  
The Other ◽  
Amorphous Chalcogenide ◽  
Exciton Recombination ◽  
Excitation Laser ◽  
Temperature Sample ◽  
Continuous Wave Light

Amorphous chalcogenide glasses are intrinsically metastable, highly photosensitive, and therefore exhibit numerous light-induced effects upon bandgap and sub-bandgap illumination. Depending on the pulse duration of the excitation laser, ChGs exhibit a series of light-induced effects spanning over femtosecond to seconds time domain. For continuous wave (CW) illumination, the effects are dominantly metastable in terms of photodarkening (PD) and photobleaching (PB) that take place via homopolar to heteropolar bond conversion. On the other hand, under nanosecond and ultrafast pulsed illumination, ChGs exhibit transient absorption (TA) that is instigated from the transient bonding rearrangements through self-trapped exciton recombination. In the first part of the review, we pay special attention to continuous wave light-induced PD and PB, while in the second part we will focus on the TA and controlling such effects via internal and external parameters, e.g., chemical composition, temperature, sample history, etc.

scholarly journals Lightinduced Effects in Amorphous Chalcogenide Glasses: Femtoseconds to Seconds

2021 ◽  
Author(s):  
Pritam Khan ◽  
K. V. Adarsh
Keyword(s):  
Chemical Composition ◽  
Time Domain ◽  
Chalcogenide Glasses ◽  
Continuous Wave ◽  
Transient Absorption ◽  
The Other ◽  
Amorphous Chalcogenide ◽  
Exciton Recombination ◽  
Excitation Laser ◽  
Temperature Sample

Amorphous chalcogenide (ChGs) glasses are intrinsically metastable, highly photosensitive, and therefore exhibit numerous lightinduced effects upon bandgap and sub-bandgap illumination. Depending on the pulse duration of the excitation laser, ChGs exhibit a series of lightinduced effects spanning over femtosecond to seconds time domain. For continuous wave illumination, the effects are dominantly metastable in terms of photodarkening (PD) and photobleaching (PB) that takes place via homopolar to heteropolar bond conversion. On the other hand, under nanosecond and ultrafast pulsed illumination, ChGs exhibit transient absorption (TA) that is instigated from the transient bonding rearrangements through self-trapped exciton recombination. In the first part of the review, we pay special attention to continuous wave lightinduced PD and PB, while in the second part we will focus on the TA and controlling such effects via internal and external parameters e.g., chemical composition, temperature, sample history etc.

scholarly journals A Local Oscillator Phase Compensation Technique for Ultra-Wideband Stepped-Frequency Continuous Wave Radar Based on a Low-Cost Software-Defined Radio

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 780
Author(s):  
Kazunori Takahashi ◽  
Takashi Miwa
Keyword(s):  
Software Defined Radio ◽  
Initial Phase ◽  
Continuous Wave ◽  
Low Cost ◽  
Local Oscillator ◽  
The Other ◽  
Ultra Wideband ◽  
Single Frequency ◽  
Wave Radar ◽  
Stepped Frequency

The paper discusses a way to configure a stepped-frequency continuous wave (SFCW) radar using a low-cost software-defined radio (SDR). The most of high-end SDRs offer multiple transmitter (TX) and receiver (RX) channels, one of which can be used as the reference channel for compensating the initial phases of TX and RX local oscillator (LO) signals. It is same as how commercial vector network analyzers (VNAs) compensate for the LO initial phase. These SDRs can thus acquire phase-coherent in-phase and quadrature (I/Q) data without additional components and an SFCW radar can be easily configured. On the other hand, low-cost SDRs typically have only one transmitter and receiver. Therefore, the LO initial phase has to be compensated and the phases of the received I/Q signals have to be retrieved, preferably without employing an additional receiver and components to retain the system low-cost and simple. The present paper illustrates that the difference between the phases of TX and RX LO signals varies when the LO frequency is changed because of the timing of the commencement of the mixing. The paper then proposes a technique to compensate for the LO initial phases using the internal RF loopback of the transceiver chip and to reconstruct a pulse, which requires two streaming: one for the device under test (DUT) channel and the other for the internal RF loopback channel. The effect of the LO initial phase and the proposed method for the compensation are demonstrated by experiments at a single frequency and sweeping frequency, respectively. The results show that the proposed method can compensate for the LO initial phases and ultra-wideband (UWB) pulses can be reconstructed correctly from the data sampled by a low-cost SDR.

A SIMPLE OBSERVER OF THE HYPERCHAOTIC RÖSSLER SYSTEM

2010 ◽  
Vol 24 (22) ◽  
pp. 4325-4331
Author(s):  
XING-YUAN WANG ◽  
JUN-MEI SONG
Keyword(s):  
Dynamical System ◽  
Time Domain ◽  
Global Exponential Stability ◽  
Observer Design ◽  
The Other ◽  
State Observation ◽  
Rossler System ◽  
Error System ◽  
Rössler System ◽  
The Time Domain

This paper studies the hyperchaotic Rössler system and the state observation problem of such a system being investigated. Based on the time-domain approach, a simple observer for the hyperchaotic Rössler system is proposed to guarantee the global exponential stability of the resulting error system. The scheme is easy to implement and different from the other observer design that it does not need to transmit all signals of the dynamical system. It is proved theoretically, and numerical simulations show the effectiveness of the scheme finally.

scholarly journals A Method for Fabricating Arrays of Nanopatterns with the Feature Size beyond Diffraction Limit

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Shuhong Li ◽  
Lifang Shi ◽  
Xiaochun Dong ◽  
Chunlei Du ◽  
Yudong Zhang
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Diffraction Limit ◽  
Evanescent Waves ◽  
The Other ◽  
Optical Intensity ◽  
Polystyrene Spheres ◽  
Feature Size ◽  
Contact Points ◽  
Difference Time

A convenient lithographic technique is proposed in this paper, which can be used to produce subdiffraction-limit arrays of nanopatterns over large areas (about several square centimeters). An array of polystyrene spheres (PS) is arranged on the surface of a layer of silver which has a thickness of about tens of nanometers. With the normal illumination light of wavelength 365 nm perpendicular to the substrate, PS can generate an array of optical patterns with high intensity at their contact points with silver. By designing the silver slab, the evanescent waves that carry subwavelength information about the optical patterns are substantially enhanced, while propagating components are restrained. In the photoresist which is on the other side of silver, the optical intensity is redistributed and subdiffraction-limit patterns are obtained after exposure and development. Simulation by finite-difference time-domain (FDTD) and experiments were carried out to verify the technique. The results show that by using PS with diameter of 600 nm, nanopatterns with dimension of less than 80 nm can be obtained.

scholarly journals "In vitro" evaluation of the apical sealing of root canals obturated with different techniques

2003 ◽  
Vol 11 (3) ◽  
pp. 181-185 ◽  
Author(s):  
Viviane Haiub Brosco ◽  
Norberti Bernardineli ◽  
Ivaldo Gomes de Moraes
Keyword(s):  
Continuous Wave ◽  
The Other ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Root Canals ◽  
Gutta Percha ◽  
Sealing Ability ◽  
Better Than ◽  
Positive Controls

The purpose of this study was to compare the apical sealing of root canals obturated with different techniques. One hundred-six human mandibular incisors were submitted to instrumentation by means of the step-back technique. After instrumentation, one hundred teeth received an impermeable coating on the external surfaces of the crown and root (except for the area nearby the apical foramen). Afterwards, they were divided in five groups containing twenty elements each, according to the obturation technique employed: 1. lateral condensation with Kerr file; 2. continuous wave of condensation technique with System B; 3. thermoplasticized injectable gutta-percha technique with the Ultrafil system; 4. mechanically thermoplasticized gutta-percha with the JS Quick-Fill system and 5. thermoplasticized gutta-percha associated to a master cone with the Microseal system. The six remaining teeth were employed as negative and positive controls. After obturation, the access cavities were sealed and the teeth were immersed in aqueous 2% methylene blue dye for 72 hours at 37ºC. After that, the teeth were longitudinally sectioned and the apical microleakage was evaluated in a stereomicroscope. The Microseal system presented the best apical sealing ability, followed by System B, JS Quick-Fill, Ultrafil and the lateral condensation technique. The statistical analysis of the results demonstrated that: 1. the Microseal system presented an apical sealing similar to System B and better than the other groups; 2. System B presented better apical sealing than the lateral condensation technique, being similar to the other groups; and 3. the lateral condensation, Ultrafil and JS Quick-Fill groups demonstrated similar sealing ability.

scholarly journals Si photonic crystal optical antenna serial array and frequency-modulated continuous-wave light detection and ranging action

2021 ◽  
Vol 119 (23) ◽  
pp. 231103
Author(s):  
Ryo Tetsuya ◽  
Takemasa Tamanuki ◽  
Hiroyuki Ito ◽  
Hiroshi Abe ◽  
Ryo Kurahashi ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Continuous Wave ◽  
Light Detection And Ranging ◽  
Optical Antenna ◽  
Light Detection ◽  
Continuous Wave Light

FROZEN MODE IN PHOTONIC CRYSTAL WAVEGUIDE

2014 ◽  
Vol 28 (07) ◽  
pp. 1450016
Author(s):  
YE LIU ◽  
LIN LUO ◽  
CHUN JIANG
Keyword(s):  
Photonic Crystal ◽  
Time Domain ◽  
Photonic Band Gap ◽  
The Other ◽  
Fdtd Simulation ◽  
Photonic Crystal Waveguide ◽  
Slow Mode ◽  
Slow Group ◽  
Photonic Band ◽  
Finite Different Time Domain

We propose a structure of 2D photonic crystal waveguide composed of hexagonal lattices of air holes in high index materials. Frozen mode regime can be observed within the photonic band gap. Light incident into the waveguide is coupled into two modes. One mode has enhanced amplitude and the other one has slow group velocity. Finite-different time-domain (FDTD) simulation is used to demonstrate the propagation of the slow mode.

scholarly journals Design of Two Novel Dual Band-Notched UWB Antennas

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Bing Li ◽  
Jing-song Hong
Keyword(s):  
Time Domain ◽  
Simple Structure ◽  
The Other ◽  
Ultra Wideband ◽  
Dual Band ◽  
Uwb Antennas ◽  
Monopole Antennas ◽  
Printed Monopole ◽  
The Difference ◽  
The Time Domain

Two novel dual band-notched ultra-wideband (UWB) printed monopole antennas with simple structure and small size are presented. The size of both antennas is25×25×0.8 mm3. The bandwidth of one of the proposed antenna can be from 2.7 GHz to 36.8 GHz, except the bandwidth of 3.2–3.9 GHz for WiMAX applications and 5.14–5.94 GHz for WLAN applications. The bandwidth of the other is ranging for 2.7 to 41.1 GHz, except the bandwidth of 3.2–3.9 GHz for WiMAX applications and 4.8–5.9 GHz for WLAN applications. Bandwidths of the antennas are about 512% and 455% wider than those of conventional band-notched UWB antennas, respectively. In addition, the time-domain characteristics of the two antennas are investigated to show the difference between both antennas.

scholarly journals Tailoring of multi-pulse dynamics in mode-locked laser via optoacoustic manipulation of quasi-continuous-wave background

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Ki Sang Lee ◽  
Chang Kyun Ha ◽  
Kyoung Jun Moon ◽  
Dae Seok Han ◽  
Myeong Soo Kang
Keyword(s):  
Information Processing ◽  
Time Domain ◽  
Continuous Wave ◽  
Single Pulse ◽  
Laser Cavity ◽  
Temporal Position ◽  
Optical Information ◽  
Pulse Dynamics ◽  
Mode Locked Laser ◽  
The Time Domain

Abstract Various nonequilibrium multi-pulse states can emerge in a mode-locked laser through interactions between the quasi-continuous-wave background (qCWB) and pulses inside the laser cavity. While they have been regarded as unpredictable and hardly controllable due to the noise-like nature of qCWB, we here demonstrate that the qCWB landscape can be manipulated via optoacoustically mediated pulse-to-qCWB interactions, which alters the behaviors of multi-pulse dynamics. In this process, impulsive qCWB modulations are created at well-defined temporal locations, which act as the point emitters and attractive potentials for drifting pulse bunches and soliton rains. Hence, we can transport a single pulse bunch from a certain temporal position to another, and also make soliton rains created and collided exclusively at specific temporal locations. Our study opens up possibilities to control the nonequilibrium multi-pulse phenomena precisely in the time domain, which would offer a practical means of advanced optical information processing.

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