Numerical investigation on the femtosecond pulse propagation and free carriers’ evolution in silicon-on-insulator waveguides

The femtosecond pulse propagation and free carriers’ evolution in the silicon-on-insulator (SOI) waveguides have been numerically investigated considering the carrier’s lifetime and the pulse width of the input pulse at 1.5 [Formula: see text]m regime. Numerical results show that the free carriers’ density profile becomes gentle between the leading edge and trailing edge of the pulse in time domain due to the decreasing of the pulse intensity caused by the nonlinear absorption, which becomes more remarkable when the pulse width expands. It can be found that lifetime ranging from 5 ns to 100 ns does not affect the free carriers’ evolution clearly in femtosecond regime. In addition, the refractive index modulation can be appeared in the process of pulse propagation and free carriers evolution with lower peak power of 200 W. This research can supply some contribution to the insight of free carriers evolution in SOI waveguides.

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Temperature and Pulse-Energy Range Suitable for Femtosecond Pulse Transmission in Si Nanowire Waveguide

Applied Sciences ◽

10.3390/app10238429 ◽

2020 ◽

Vol 10 (23) ◽

pp. 8429

Author(s):

Xiaochun Wang ◽

Meicheng Fu ◽

Heng Yang ◽

Jiali Liao ◽

Xiujian Li

Keyword(s):

Energy Range ◽

Pulse Energy ◽

Femtosecond Pulse ◽

Input Pulse ◽

Silicon On Insulator ◽

Oxide Semiconductors ◽

Optical Gating ◽

Pulse Transmission ◽

Input Pulse Energy ◽

Different Temperatures

We experimentally measured the femtosecond pulse transmission through a silicon-on-insulator (SOI) nanowire waveguide under different temperatures and input pulse energy with a cross-correlation frequency-resolved optical gating (XFROG) measurement setup. The experimental results demonstrated that the temperature and pulse energy dependence of the Si photonic nanowire waveguide (SPNW) is interesting rather than just monotonous or linear, and that the suitable temperature and pulse-energy range is as suggested in this experiment, which will be valuable for analyzing the practical design of the operating regimes and the fine dispersion engineering of various ultrafast photonic applications based on the SPNWs. The research results will contribute to developing the SPNWs with photonic elements and networks compatible with mature complementary metal–oxide–semiconductors (CMOS).

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IMPLEMENTATION OF OVERLAPPING SOLITON PAIR TO REDUCE TIME DELAY IN FEMTOSECOND PULSE PROPAGATION OVER SHORT STANDARD SINGLE MODE FIBER

Modern Physics Letters B ◽

10.1142/s0217984911027297 ◽

2011 ◽

Vol 25 (26) ◽

pp. 2091-2098

Author(s):

A. ESMAEILIAN-MARNANI ◽

A. F. ABAS ◽

M. A. MAHDI ◽

K. SAMSUDIN

Keyword(s):

Time Delay ◽

Femtosecond Pulse ◽

Pulse Propagation ◽

Input Pulse ◽

Single Mode ◽

Propagation Characteristic ◽

Single Mode Fiber ◽

Average Amplitude ◽

Soliton Pulse ◽

Soliton Pair

Propagation of 50 femtosecond soliton pulse over short Standard Single Mode Fiber (SSMF) is reported by using soliton pair as the input pulse. The attraction of two solitons to propagate as one pulse is intended. The time deviation and average amplitude of propagating pulses are compared for several soliton orders and initial inter-pulse delays. It is discovered that by considering overlapping soliton pair as the input pulse, under special conditions, better propagation characteristic and lower time delay is experienced over short SSMF in comparison to the fundamental soliton.

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ANALYTICAL SOLUTIONS FOR THE VARIATIONAL EQUATIONS DERIVED FOR THE NONLINEAR SCHRÖDINGER EQUATION: DISPERSION-MANAGED FIBER SYSTEM

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s0218863508004226 ◽

2008 ◽

Vol 17 (03) ◽

pp. 285-297 ◽

Cited By ~ 1

Author(s):

ABDOSLLAM M. ABOBAKER ◽

A. B. MOUBISSI ◽

TH. B. EKOGO ◽

K. NAKKEERAN

Keyword(s):

Schrödinger Equation ◽

Nonlinear Schrödinger Equation ◽

Pulse Width ◽

Schrodinger Equation ◽

Pulse Propagation ◽

Nonlinear Schrodinger Equation ◽

Fiber System ◽

Variational Equations ◽

Nonlinear Schrödinger ◽

The Given

We consider the nonlinear Schrödinger equation which governs the pulse propagation in dispersion-managed (DM) optical fiber transmission systems. Using a generalized form of ansatz function for the shape of the pulse, we derive the variational equations. For a particular case of DM fiber systems when the Hamiltonian is zero, we solve the variational equations analytically and obtain the expressions for the pulse energy, amplitude, width and chirp. Finally for Gaussian and hyperbolic secant shaped pulses, we show through numerical simulations that the analytically calculated energy (for the given pulse width and chirp) is good enough to support the periodic evolution of the DM soliton. The simulations are carried out for conventional and dense DM fiber systems for both lossless and lossy cases.

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Study on Recast Phenomenon in Processing of Micro-Hole with Millisecond Laser

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.459.315 ◽

2012 ◽

Vol 459 ◽

pp. 315-319 ◽

Cited By ~ 1

Author(s):

Ke Dian Wang ◽

Wen Qiang Duan ◽

Xue Song Mei ◽

Wen Jun Wang

Keyword(s):

Stainless Steel ◽

Titanium Alloy ◽

Pulse Width ◽

Peak Power ◽

Recast Layer ◽

Hole Depth ◽

Maximum Peak ◽

Blind Hole ◽

Micro Hole ◽

Millisecond Laser

The experiments of micro-hole ablation are conducted firstly on titanium alloy Ti-6Al-4V with Nd: YAG millisecond laser. A significant factor which affects the depth of blind hole is found: the depth of recast material. This paper closely examines the regularity of recast depth varying with laser parameters, discovering that the ratio of recast depth to the entire hole depth decreases as pulse width decreases, and increases as peak power decreases. Verification experiment is conducted on stainless steel 1Cr13, eventually micro-hole with very thin recast layer is drilled when the maximum peak power and the minimum pulse width of the present millisecond laser are used.

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Efficient simulation of unidirectional pulse propagation in high-contrast nonlinear nanowaveguides

Mathematics of Quantum Technologies ◽

10.2478/nsmmt-2013-0010 ◽

2013 ◽

Vol 2 (1) ◽

Author(s):

Jonathan Andreasen ◽

Miroslav Kolesik

Keyword(s):

Total Internal Reflection ◽

Femtosecond Pulse ◽

Transverse Direction ◽

Pulse Propagation ◽

Improved Method ◽

Long Distance ◽

Efficient Simulation ◽

Index Contrast ◽

Propagation Methods ◽

Beam Propagation Methods

AbstractThis work demonstrates an improved method to simulate long-distance femtosecond pulse propagation in highcontrast nanowaveguides. Different from typical beam propagation methods, the foundational tool here is capable of simulating strong spatiotemporal waveform reshaping and extreme spectral dynamics. Meanwhile, the ability to fully capture effects due to index contrast in the transverse direction is retained, without requiring a decomposition of the electric field in terms of waveguide modes. These simulations can be computationally expensive, however, so cost is reduced in the improved method by considering only the waveguide core. Fields in the cladding are then properly accounted for through a boundary condition suitable for the case of total internal reflection.

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Interplay Between Dispersion and Nonlinearity in Femtosecond Soliton Management

Zeitschrift für Naturforschung A ◽

10.1515/zna-2010-6-710 ◽

2010 ◽

Vol 65 (6-7) ◽

pp. 549-554

Author(s):

Ramaswamy Radha ◽

Vaduganathan Ramesh Kumar

Keyword(s):

Pulse Propagation ◽

Group Velocity Dispersion ◽

Soliton Solutions ◽

Higher Order ◽

Order Effects ◽

Nls Equation ◽

Linear Eigenvalue Problem ◽

Third Order Dispersion ◽

Femtosecond Regime ◽

Soliton Management

In this paper, we investigate the inhomogeneous higher-order nonlinear Schr¨odinger (NLS) equation governing the femtosecond optical pulse propagation in inhomogeneous fibers using gauge transformation and generate bright soliton solutions from the associated linear eigenvalue problem. We observe that the amplitude of the bright solitons depends on the group velocity dispersion (GVD) and the self-phase modulation (SPM) while its velocity is dictated by the third-order dispersion (TOD) and GVD. We have shown how the interplay between GVD, SPM, and TOD can be profitably exploited to change soliton width, amplitude (intensity), shape, phase, velocity, and energy for an effective femtosecond soliton management. The highlight of our paper is the identification of ‘optical similaritons’ arising by virtue of higher-order effects in the femtosecond regime.

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Stable continuous-wave mode-locked laser from a 1645 nm Er:YAG ceramic oscillator

Applied Physics Express ◽

10.35848/1882-0786/ac481c ◽

2022 ◽

Author(s):

Yangyu Liu ◽

Xue Cao ◽

AnHua Xian ◽

Guangmiao Liu ◽

Wei zhou ◽

...

Keyword(s):

Solid State ◽

Pulse Width ◽

Peak Power ◽

Continuous Wave ◽

Modulation Depth ◽

Average Power ◽

Mode Locking ◽

Wave Mode ◽

Semiconductor Saturable Absorber ◽

Continuous Wave Mode

Abstract We demonstrate stable continuous-wave mode-locking (CWML) pulses around 1645nm by employing the home-made Er:YAG ceramic. By using a fiber laser and semiconductor saturable absorber mirror (SESAM) with modulation depth of 1.2%, we get ML pulses with the output average power up to 815 mW, the pulse width shortened as ~4 ps, and the peak power of 1.8 kW. With the SESAM of modulation depth of 2.4%, the second-order harmonic ML pulses were also obtained. As far as we know, this is the first report of CWML from Er3+-doped ceramics and also the shortest pulse duration in Er3+-doped solid-state oscillators.

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Comparison of Wind Tunnel Airfoil Performance Data With Wind Turbine Blade Data

Journal of Solar Energy Engineering ◽

10.1115/1.2929989 ◽

1992 ◽

Vol 114 (2) ◽

pp. 119-124 ◽

Cited By ~ 12

Author(s):

C. P. Butterfield ◽

George Scott ◽

Walt Musial

Keyword(s):

Wind Tunnel ◽

Wind Turbine ◽

Peak Power ◽

Unsteady Aerodynamics ◽

Leading Edge ◽

Operating Conditions ◽

Performance Data ◽

Horizontal Axis Wind Turbine ◽

Force Coefficients ◽

Basic Fluid

Horizontal axis wind turbine (HAWT) performance is usually predicted by using wind tunnel airfoil performance data in a blade element momentum theory analysis. This analysis assumes that the rotating blade airfoils will perform as they do in the wind tunnel. However, when stall-regulated HAWT performance is measured in full-scale operation, it is common to find that peak power levels are significantly greater than those predicted. Pitch-controlled rotors experience predictable peak power levels because they do not rely on stall to regulate peak power. This has led to empirical corrections to the stall predictions. Viterna and Corrigan (1981) proposed the most popular version of this correction. But very little insight has been gained into the basic cause of this discrepancy. The National Renewable Energy Laboratory (NREL), funded by the DOE, has conducted the first phase of an experiment which is focused on understanding the basic fluid mechanics of HAWT aerodynamics. Results to date have shown that unsteady aerodynamics exist during all operating conditions and dynamic stall can exist for high yaw angle operation. Stall hysteresis occurs for even small yaw angles and delayed stall is a very persistent reality in all operating conditions. Delayed stall is indicated by a leading edge suction peak which remains attached through angles of attack (AOA) up to 30 degrees. Wind tunnel results show this peak separating from the leading edge at 18 deg AOA. The effect of this anomaly is to raise normal force coefficients and tangent force coefficients for high AOA. Increased tangent forces will directly affect HAWT performance in high wind speed operation. This report describes pressure distribution data resulting from both wind tunnel and HAWT tests. A method of bins is used to average the HAWT data which is compared to the wind tunnel data. The analysis technique and the test set-up for each test are described.

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Accurate Measurements of Wall Shear Stress on a Plate with Elliptic Leading Edge

Sensors ◽

10.3390/s18082682 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2682 ◽

Cited By ~ 2

Author(s):

Guang-Hui Ding ◽

Bing-He Ma ◽

Jin-Jun Deng ◽

Wei-Zheng Yuan ◽

Kang Liu

Keyword(s):

Shear Stress ◽

Wind Tunnel ◽

Wall Shear Stress ◽

Leading Edge ◽

Reynold Number ◽

Micro Electro Mechanical System ◽

Flow Speed ◽

Silicon On Insulator ◽

Micro Sensor ◽

Wall Shear

A micro-floating element wall shear stress sensor with backside connections has been developed for accurate measurements of wall shear stress under the turbulent boundary layer. The micro-sensor was designed and fabricated on a 10.16 cm SOI (Silicon on Insulator) wafer by MEMS (Micro-Electro-Mechanical System) processing technology. Then, it was calibrated by a wind tunnel setup over a range of 0 Pa to 65 Pa. The measurements of wall shear stress on a smooth plate were carried out in a 0.6 m × 0.6 m transonic wind tunnel. Flow speed ranges from 0.4 Ma to 0.8 Ma, with a corresponding Reynold number of 1.05 × 106~1.55 × 106 at the micro-sensor location. Wall shear stress measured by the micro-sensor has a range of about 34 Pa to 93 Pa, which is consistent with theoretical values. For comparisons, a Preston tube was also used to measure wall shear stress at the same time. The results show that wall shear stress obtained by three methods (the micro-sensor, a Preston tube, and theoretical results) are well agreed with each other.

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