Dispersion decreasing fibres for soliton generation and transmission line loss compensation

The idea of varying the axial distribution of dispersion along a length of optical fibre as a means of manipulating and controlling the soliton supporting nature of the fibre and thereby the characteristics of soliton pulses propagating through the medium has been around for some while. A number of specific applications have been suggested in particular techniques for bright and dark soliton generation, pulse compression and most notably techniques for high frequency soliton transmission. The experimental realisation of most of these techniques however has been hindered by difficulties in the reliable fabrication of dispersion varying fibres. A technique for the fabrication of such fibres was first developed by workers at General Physics Institute, Moscow. Control of the waveguide dispersion was achieved by active control of fibre diameter during the pull. Fibre lengths of up to 2km were fabricated and successfully used in the first experimental demonstrations of high frequency (>60 GHz) bright soliton generation and pulse compression. Subsequent to these first experimental results a number of other groups have commenced fabrication programs on such fibres, extending the techniques to fibre lengths of 40km. In this presentation we describe our latest achievements in Dispersion Decreasing Fibre (DDF) fabrication and report on two applications of the technology. Firstly, we describe a robust, diode-pumped, 40GHz bright soliton transmitter, and secondly we demonstrate loss compensation in a 38km loss-matched dispersion varying fibre

On the lowest eigenvalue of Laplace operators with mixed boundary conditions

In this paper we consider a Robin-type Laplace operator on bounded domains. We study the dependence of its lowest eigenvalue on the boundary conditions and its asymptotic behavior in shrinking and expanding domains. For convex domains we establish two-sided estimates on the lowest eigenvalues in terms of the inradius and of the boundary conditions

Locally erasable couplers for optical device testing in silicon on insulator

Wafer scale testing is critical to reducing production costs and increasing production yield. Here we report a method that allows testing of individual optical components within a complex optical integrated circuit. The method is based on diffractive grating couplers, fabricated using lattice damage induced by ion implantation of germanium. These gratings can be erased via localised laser annealing, which is shown to reduce the outcoupling efficiency by over 20 dB after the device testing is completed. Laser annealing was achieved by employing a CW laser, operating at visible wavelengths thus reducing equipment costs and allowing annealing through thick oxide claddings. The process used also retains CMOS compatibility

Dark soliton generation and propagation using a normally dispersive, dispersion decreasing fiber

The generation and propagation of bright and dark soliton pulses is an area of great scientific interest with relevance to many futuristic telecommunication and optical-processing applications. Bright solitons have been the subject of intense experimental investigation; however, the experimental study of dark soliton behaviour has been limited. This situation is in no small part due to the difficulty of generating and measuring such pulse forms [1,2,3]. (for review see Ref.[4] and references within)

Transmission and modulation of 30-40 GHz pulses generated by a diode-driven, low-jitter, beat-signal to soliton train conversion source

We report on the performance of a low timing-jitter, diode-driven, Nd:YLF pumped 5ps, 30-40 GHz soliton source based on beat signal conversion in a dispersion decreasing fibre. We demonstrate for the first time data encoding at 40 Gbit/s and transmission of the pulse trains over 205 km

High-frequency bright and dark soliton sources based on dispersion-profiled fibre circuitry and their applications

We report advances in the area of soliton generation using beat signal conversion. In particular, we describe the development of a diode-driven, 40 GHz bright soliton source with sub 300 fs pulse jitter. Furthermore we report pulse transmission and all-optical data encoding at 40 Gbit/s

Two Mathematically Equivalent Versions of Maxwell's Equations

This paper is a review of the canonical proper-time approach to relativistic mechanics and classical electrodynamics. The purpose is to provide a physically complete classical background for a new approach to relativistic quantum theory. Here, we first show that there are two versions of Maxwell's equations. The new version fixes the clock of the field source for all inertial observers. However now, the (natural definition of the effective) speed of light is no longer an invariant for all observers, but depends on the motion of the source. This approach allows us to account for radiation reaction without the Lorentz-Dirac equation, self-energy (divergence), advanced potentials or any assumptions about the structure of the source. The theory provides a new invariance group which, in general, is a nonlinear and nonlocal representation of the Lorentz group. This approach also provides a natural (and unique) definition of simultaneity for all observers. The corresponding particle theory is independent of particle number, noninvariant under time reversal (arrow of time), compatible with quantum mechanics and has a corresponding positive definite canonical Hamiltonian associated with the clock of the source. We also provide a brief review of our work on the foundational aspects of the corresponding relativistic quantum theory. Here, we show that the standard square-root and the Dirac equations are actually two distinct spin-$\tfrac{1}{2}$ particle equations.Comment: Appeared: Foundations of Physic

An assessment of pulse transit time for detecting heavy blood loss during surgical operation

Copyright @ Wang et al.; Licensee Bentham Open. This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.The main contribution of this paper is the use of non-invasive measurements such as electrocardiogram (ECG) and photoplethysmographic (PPG) pulse oximetry waveforms to develop a new physiological signal analysis technique for detecting blood loss during surgical operation. Urological surgery cases were considered as the control group due to its generality, and cardiac surgery as experimental group since it involves blood loss and water supply. Results show that the control group has the tendency of a reduction of the pulse transient time (PTT), and this indicates an increment in the blood flow velocity changes from slow to fast. While for the experimental group, the PTT indicates high values during blood loss, and low values during water supply. Statistical analysis shows considerable differences (i.e., P <0.05) between both groups leading to the conclusion that PTT could be a good indicator for monitoring patients' blood loss during a surgical operation.The National Science Council (NSC) of Taiwan and the Centre for Dynamical Biomarkers and Translational Medicine, National Central University, Taiwan

Unimodality Problems in Ehrhart Theory

Ehrhart theory is the study of sequences recording the number of integer points in non-negative integral dilates of rational polytopes. For a given lattice polytope, this sequence is encoded in a finite vector called the Ehrhart $h^*$-vector. Ehrhart $h^*$-vectors have connections to many areas of mathematics, including commutative algebra and enumerative combinatorics. In this survey we discuss what is known about unimodality for Ehrhart $h^*$-vectors and highlight open questions and problems.Comment: Published in Recent Trends in Combinatorics, Beveridge, A., et al. (eds), Springer, 2016, pp 687-711, doi 10.1007/978-3-319-24298-9_27. This version updated October 2017 to correct an error in the original versio

The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect