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Article
Publication date: 14 November 2008

Carlos Alberto Ferreira Fernandes

The aim of this paper is to develop simulation tools for the analysis of modified structures of distributed feedback (DFB) laser diodes adequate for single longitudinal mode (SLM…

Abstract

Purpose

The aim of this paper is to develop simulation tools for the analysis of modified structures of distributed feedback (DFB) laser diodes adequate for single longitudinal mode (SLM) operation.

Design/methodology/approach

The paper uses matricial techniques: the transfer matrix method (TMM). When compared to the eigenvalue approach, the matricial techniques are more general and flexible and hence are especially adequate to deal with the analysis and structural design of DFB laser diodes. In this work, the author makes a general description of the TMM, enhancing its importance with some applications by considering the threshold and above‐threshold analysis of a modified DFB laser structure.

Findings

The increasing demands on laser performance, mainly in the area of optical communication systems, have lead to the fabrication of more‐and‐more complex structures. In viewing the development of the associated technology, the importance of the simulation tools revealed of crucial importance.

Originality/value

The simulation model used in this work has been described in other works of the author. In the present analysis a general description of the TMM was implemented, summarizing the results of previous studies for the threshold and above‐threshold regimes of modified DFB laser structures specially designed to show SLM operation.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 February 1990

O. Hildebrand, J. Benoit and A. Duda

Optoelectronic components such as lasers and avalanche photodiodes have already revolutionised long distance transmission, and yet the technology is still in its infancy. Future…

Abstract

Optoelectronic components such as lasers and avalanche photodiodes have already revolutionised long distance transmission, and yet the technology is still in its infancy. Future generations of optoelectronic components will see the increasing integration of electronic, optoelectronic and optical functions on single chips, bringing about dramatic improvements in performance and the lower costs that will be required for widescale introduction of broadband networks and services.

Details

Microelectronics International, vol. 7 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 23 February 2018

Yage Zhan, Ziyang Shen, Zeyu Sun, Qiao Yu, Hong Liu and Yong Kong

The purpose of this paper is to theoretically analyze and experimentally demonstrate the investigation of and present a kind of sensing system for monitoring simultaneous…

Abstract

Purpose

The purpose of this paper is to theoretically analyze and experimentally demonstrate the investigation of and present a kind of sensing system for monitoring simultaneous temperature and strain measurements based on highly nonlinear fiber (HNLF) and single mode fiber (SMF).

Design/methodology/approach

First, the stimulated Brillouin scattering (SBS) characteristics of the HNLF have been studied, including the Brillouin gain bandwidth, Brillouin gain center frequency and SBS threshold. Second, based on the Brillouin gain center frequency, the Brillouin frequency shift coefficients of strain and temperature in HNLF have been studied. Third, the sensing and signal interrogation scheme for simultaneous monitoring of temperature and strain with high resolution has been presented.

Findings

It is found that the HNLF has a wider Brillouin gain bandwidth. The SBS threshold of HNLF is 78 mW, which is much larger than 7.9 mW of SMF. Also, the Brillouin frequency shift coefficients of strain and temperature in HNLF are 0.0308 and 0.413 MHz/°C, respectively.

Originality/value

The larger threshold of SBS is useful to avoid SBS under certain situations that Spontaneous Brillouin Scattering is necessary and should be applied. The technique is based on the fact that the Brillouin frequency shift coefficients of strain and temperature in HNLF are different from those in SMF. Therefore, the two-parameter monitoring can be achieved by producing SBS and obtaining the back-scattering Brillouin signal light simultaneously in HNLF and SMF.

Details

Sensor Review, vol. 39 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 25 January 2011

Robert Bogue

This paper aims to provide a technical insight into recent developments in organic lasers and their applications to sensing.

Abstract

Purpose

This paper aims to provide a technical insight into recent developments in organic lasers and their applications to sensing.

Design/methodology/approach

Following a review of progress in organic lasers, this paper considers a number of recent sensor developments based on this technology. Finally, future prospects are briefly considered.

Findings

This shows that organic lasers are the tropic of a major research effort. The broad aims are to reduce the optical pumping power and ultimately to achieve purely electrical operation. Few sensors based on organic lasers have yet been reported but recent examples include explosive vapour detectors, lab‐on‐a‐chip devices and biosensors.

Originality/value

This paper provides a review of organic laser developments and sensors that exploit this technology.

Details

Sensor Review, vol. 31 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 April 1991

V. Jayan and P.R. Vaya

SEM picture of rectangular gratings realised by chemical etching mostly resembled a triangular grating. Symmetric triangular gratings can give better directionality to the DFB

Abstract

SEM picture of rectangular gratings realised by chemical etching mostly resembled a triangular grating. Symmetric triangular gratings can give better directionality to the DFB laser beam. In this communication,the optimal Bragg order,grating period and tooth height,active layer thickness were presented from a study of the optical power coupling for a symmetric triangular GaAs‐AlGaAs structure. The numerical parameters so obtained were compared to the reported results and found that chemically etched rectangular grating obeys the theory of symmetric triangular grating with remarkable accuracy.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 10 no. 4
Type: Research Article
ISSN: 0332-1649

Article
Publication date: 1 May 2003

G. Stewart, B. Culshaw, W. Johnstone, G. Whitenett, K. Atherton and A. McLean

Describes the author's work on the development of fibre sensors and networks for monitoring trace gases such as methane, acetylene, carbon dioxide, carbon monoxide, hydrogen…

Abstract

Describes the author's work on the development of fibre sensors and networks for monitoring trace gases such as methane, acetylene, carbon dioxide, carbon monoxide, hydrogen sulphide and for detection of spills of gasoline, diesel and organic solvents, all of which are important in environmental and safety management. As an example, a 45‐point fibre optic sensor network has been installed on a landfill site to assess the distribution of methane generation across the site. System operation is based on near‐IR absorption and is currently being extended to monitor other gases such as carbon dioxide and hydrogen sulphide. Concurrently, research is being conducted on fibre lasers for the realisation of multi‐point, multi‐gas monitoring systems. Based on other principles (periodic micro‐bending loss effects), detection of hydrocarbon fuel spills has been demonstrated at multiple locations along the length of a specially designed fibre optic cable using standard optical time domain reflectometry (OTDR) measurements.

Details

Management of Environmental Quality: An International Journal, vol. 14 no. 2
Type: Research Article
ISSN: 1477-7835

Keywords

Content available
Article
Publication date: 1 August 2004

81

Abstract

Details

Microelectronics International, vol. 21 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 April 1991

Z.‐M. Li, K.M. Dzurko and S.P. McAlister

We have developed a two‐dimensional model for quantum‐well lasers which solves, self‐consistently, the semiconductor equations together with the complex scalar wave equation and…

Abstract

We have developed a two‐dimensional model for quantum‐well lasers which solves, self‐consistently, the semiconductor equations together with the complex scalar wave equation and the photon rate equation. To predict the threshold current accurately we have included the wavelength‐ and position‐dependence of the gain and the spontaneous emission. For the complex wave equation successive over relaxation (SOR) is used with two adaptive acceleration parameters for the complex wave amplitude and for the eigenvalue. Since the rate equation near threshold can be driven into divergence during iteration for a steady state solution, we have introduced a special damping technique to overcome this problem. Our model enables us to predict the characteristics of a quantum‐well laser with a minimal number of empirical constants. The output of the model includes light‐current characteristics, and the current and optical field intensity distributions. We show the results of a calculation for a graded‐index separate‐confinement heterostructure single quantum‐well (GRIN‐SCH SQW) laser.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 10 no. 4
Type: Research Article
ISSN: 0332-1649

Article
Publication date: 20 March 2017

Wei Wei, Jun Chang, Qingjie Huang, Qiang Wang, Yuanyuan Liu and Zengguang Qin

As measurement results of optical gas sensors are constantly affected by the pressure of a target gas, approaches must be taken to modify the results. The purpose of this paper is…

Abstract

Purpose

As measurement results of optical gas sensors are constantly affected by the pressure of a target gas, approaches must be taken to modify the results. The purpose of this paper is to compare the traditional measurement method with the new measurement system. At the same time, measurement results of the two systems under different pressures are presented for comparison of the detection performance.

Design/methodology/approach

A theoretical model of line shape function and its impact on the measured results is presented, which is based on direct absorption and wavelength modulation spectroscopy (WMS) for gas concentration detection under different pressures. Methods of linear fitting and result modification have been illustrated and compared. A new testing system with the result modification method used for water vapor concentration detection under different pressures between 1 and 7 atm is applied. With an additional pressure sensor placed in the gas cell and calibration performed, relationships between the amplitude of the second harmonic and concentration of the target gas under different pressures can be obtained.

Findings

Amplitude detection can be used for concentration detection regardless of the change in pressure for the method of direct absorption. Although, WMS with second harmonic detection is not enough. Two methods are presented and compared with WMS under different pressures. Moreover, the result modification method shows better performance as computation is significantly reduced.

Originality/value

The comparison between linear fitting and the result modification method with WMS under different pressures is firstly presented. At the same time, a new testing system with better performance for water vapor concentration detection under different pressures is presented as well.

Details

Sensor Review, vol. 37 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 8 January 2018

Robert Bogue

This paper aims to provide a technical insight into a selection of recent developments and applications involving terahertz sensing technology.

1164

Abstract

Purpose

This paper aims to provide a technical insight into a selection of recent developments and applications involving terahertz sensing technology.

Design/methodology/approach

Following an introduction, the first part of this paper considers a selection of research activities involving terahertz radiation sources and detectors. The second part seeks to illustrate how the technology is exerting a commercial impact and discusses a number of product developments and applications.

Findings

Terahertz sensing is a rapidly developing field and a strong body of research seeks to develop sources and detectors with enhanced features which often exploit novel materials, phenomena and technologies. Commercialisation is gathering pace, and a growing number of companies are producing terahertz sensing and imaging products which are finding a diversity of applications.

Originality/value

This provides details of recent research, product developments and applications involving terahertz sensing technology.

Details

Sensor Review, vol. 38 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

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