scholarly journals Stability Boundaries in Laterally-Coupled Pairs of Semiconductor Lasers

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 74
Author(s):  
Martin Vaughan ◽  
Hadi Susanto ◽  
Nianqiang Li ◽  
Ian Henning ◽  
Mike Adams
Keyword(s):  
Semiconductor Lasers ◽  
Normal Mode ◽  
Dynamic Behaviour ◽  
Normal Modes ◽  
Stability Boundaries ◽  
Pumping Rate ◽  
One Dimensional ◽  
Coupled Mode ◽  
Normal Mode Theory ◽  
Laser Separation

The dynamic behaviour of coupled pairs of semiconductor lasers is studied using normal-mode theory, applied to one-dimensional (slab) and two-dimensional (circular cylindrical) real index confined structures. It is shown that regions of stable behaviour depend not only on pumping rate and laser separation, but also on the degree of guidance in the structures. Comparison of results between normal-mode and coupled-mode theories for these structures leads to the tentative conclusion that the accuracy of the latter is determined by the strength of self-overlap and cross-overlap of the symmetric and antisymmetric normal modes in the two lasers.

A COUPLED–MODE FORMULATION FOR THE SOLUTION OF THE HELMHOLTZ EQUATION IN WATER IN THE PRESENCE OF A CONICAL SEA-MOUNT

1996 ◽  
Vol 04 (01) ◽  
pp. 101-121 ◽  
Author(s):  
MICHAEL I. TAROUDAKIS
Keyword(s):  
Series Expansion ◽  
Acoustic Pressure ◽  
Normal Component ◽  
Normal Modes ◽  
Low Frequency ◽  
Coupled Mode ◽  
Hankel Functions ◽  
Normal Mode Theory ◽  
Cosine Functions ◽  
Linear Systems Of Equations

The problem of determining the acoustic field in the sea due to a point harmonic source around a penetrable sea-mount of conical shape is handled in terms of normal-mode theory. The sea-mount is divided in cylindrical segments-rings, in each of which, a series expansion of the acoustic pressure in terms of normal modes and cosine functions is considered. A similar series expansion is considered for the external field and the coefficients of the various expansions are calculated by solving linear systems of equations resulting from the application of the continuity conditions of the pressure field and normal component of the particle velocity at the artificial interfaces of the cylindrical segments-rings. Since Hankel functions of high order are involved in the expansions, numerical problems arise in the numerical implementation of the scheme in cases of low convergence rate. Numerical results are presented for some simple cases of very low frequency propagation around a cylindrical mount.

scholarly journals An Unsuspected Boundary-Induced Temporal Computational Mode in a Two-Time-Level Discretization

2005 ◽  
Vol 133 (3) ◽  
pp. 712-720 ◽  
Author(s):  
Andrew Staniforth ◽  
Nigel Wood
Keyword(s):  
Dispersion Relation ◽  
Normal Mode ◽  
Normal Modes ◽  
Time Level ◽  
One Dimensional ◽  
Temporal Discretization ◽  
Acoustic Equations ◽  
Continuous Equation ◽  
The One ◽  
Bounded System

Abstract Normal-mode analyses are applied to various discrete forms of the one-dimensional, linearized, vertical acoustic equations in a height-based coordinate. First, the temporally discrete, spatially continuous equations are considered and the normal modes for a bounded system are compared to those of an unbounded system. Despite the use of a two-time-level discretization, a computational mode is found in the bounded case that is absent in the unbounded case. Second, the complete temporally and spatially discrete bounded system is considered and the normal modes and associated dispersion relation are derived. No computational modes are found. However, under certain limiting conditions, the temporal discretization leads to a distortion of the physical modes so that they resemble the computational mode of the spatially continuous bounded system. Implications for analyses based on spatially continuous equation sets are discussed.

scholarly journals Measuring α-FPUT Cores and Tails

Physics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 879-887
Author(s):  
Sergej Flach
Keyword(s):  
Normal Mode ◽  
Normal Modes ◽  
Numerical Data ◽  
One Dimensional ◽  
The Core ◽  
Long Time ◽  
Good Agreement

Almost 70 years ago, the Fermi–Pasta–Ulam–Tsingou (FPUT) paradox was formulated in, observed in, and reported using normal modes of a nonlinear, one-dimensional, non-integrable string. Let us recap the paradox. One normal mode is excited, which drives three or four more normal modes in the core. Then, that is it for quite a long time. So why are many normal modes staying weakly excited in the tail? Furthermore, how many? A quantitative, analytical answer to the latter question is given here using resonances and secular avalanches A comparison with the previous numerical data is made and extremely good agreement is found.

Highly efficient one-dimensional quasi-crystalline THz semiconductor lasers

2020 ◽  
Author(s):  
Simone Biasco ◽  
Andrea Ciavatti ◽  
Lianhe Li ◽  
A. Giles Davies ◽  
Edmund H. Linfield ◽  
...  
Keyword(s):  
Semiconductor Lasers ◽  
One Dimensional ◽  
Highly Efficient

Acoustic Green's Function Approximations

1998 ◽  
Vol 06 (04) ◽  
pp. 435-452 ◽  
Author(s):  
Robert P. Gilbert ◽  
Zhongyan Lin ◽  
Klaus Hackl
Keyword(s):  
Inverse Problem ◽  
Normal Mode ◽  
Eigenvalue Problems ◽  
Normal Modes ◽  
Modal Parameters ◽  
Mindlin Plate ◽  
Ocean Bottom ◽  
Hankel Transformation ◽  
Poroelastic Materials ◽  
Function Approximations

Normal-mode expansions for Green's functions are derived for ocean–bottom systems. The bottom is modeled by Kirchhoff and Reissner–Mindlin plate theories for elastic and poroelastic materials. The resulting eigenvalue problems for the modal parameters are investigated. Normal modes are calculated by Hankel transformation of the underlying equations. Finally, the relation to the inverse problem is outlined.

Experimental Study for Extraction of Normal Modes

1995 ◽  
Author(s):  
S. Y. Chen ◽  
M. S. Ju ◽  
Y. G. Tsuei
Keyword(s):  
Frequency Response ◽  
Normal Mode ◽  
Normal Modes ◽  
Measurement Data ◽  
Mode Shapes ◽  
Complex Frequency ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Incomplete System ◽  
Coupled Structures

Abstract A frequency-domain technique to extract the normal mode from the measurement data for highly coupled structures is developed. The relation between the complex frequency response functions and the normal frequency response functions is derived. An algorithm is developed to calculate the normal modes from the complex frequency response functions. In this algorithm, only the magnitude and phase data at the undamped natural frequencies are utilized to extract the normal mode shapes. In addition, the developed technique is independent of the damping types. It is only dependent on the model of analysis. Two experimental examples are employed to illustrate the applicability of the technique. The effects due to different measurement locations are addressed. The results indicate that this technique can successfully extract the normal modes from the noisy frequency response functions of a highly coupled incomplete system.

Temporal coupled mode analysis of one-dimensional magneto-photonic crystals with cavity structures

2016 ◽  
Vol 419 ◽  
pp. 84-91 ◽  
Author(s):  
Behnam Saghirzadeh Darki ◽  
Abolghasem Zeidaabadi Nezhad ◽  
Zaker Hossein Firouzeh
Keyword(s):  
Photonic Crystals ◽  
Mode Analysis ◽  
One Dimensional ◽  
Coupled Mode

Subharmonic anti-phase dynamics in coupled mode-locked semiconductor lasers

2017 ◽  
Vol 42 (23) ◽  
pp. 4905
Author(s):  
Sudarshan Sivaramakrishnan ◽  
Herbert G. Winful
Keyword(s):  
Semiconductor Lasers ◽  
Phase Dynamics ◽  
Coupled Mode

scholarly journals Computational notes on the electronic properties of carboxylic acid

2020 ◽  
Vol 9 (2) ◽  
pp. 1079-1082
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Electronic Properties ◽  
Carboxylic Acids ◽  
Normal Mode ◽  
Normal Modes ◽  
Carboxyl Groups ◽  
Vibrational Characteristics ◽  
Vibrational Features ◽  
Acetic Acids

The present work describing the electronic properties and vibrational characteristics of carboxylic acids. Acetic acid is chosen as model molecules then optimized at B3LYP/6-31g(d,p) level of theory. The vibrational frequencies were calculated at the same level of theory. Band assignments which were calculated as 18 normal modes were assigned as one compare the normal mode coordinates with original one. Band assignments were described indicating the directions of normal modes in terms the vibrating atoms of the acetic acids. It could be concluded that DFT could be a useful tool for elucidation both the structural and vibrational features of carboxylic acids and then further utilized for assignment of the structures contains carboxyl groups which are known as most reactive structures in chemistry, biology and environment.

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