Wavelength conversion, regeneration and tone manipulation using integrated semiconductor lasers and amplifiers

An integrated semiconductor optical amplifier/distributed feedback (SOA/DFB) laser that show promise as a simple all-optical wavelength conversion device together with useful simultaneous functions such as 2R regeneration and the ability to remove a wavelength identifying tone is presented. Wavelength conversion performance at 20Gb/s and 40Gb/s can be obtained with this laser.

High power laser with integrated lens using focused ion beam etching

In this study, a collimating lens is introduced at the output facet of a tapered waveguide laser to compensate for the divergence of the optical mode. The collimating lens is shown to enhance the laser efficiency while simultaneously reducing the far field divergence.

All-optical 3R regeneration and format conversion in an integrated SOA/DFB laser

Using a compact, integrated device at 2.488Gb/s, simultaneous NRZ to RZ format conversion and regeneration was achieved. The regenerated signal has a negative BER sensitivity of -1.5dB compared with a data signal transmitted down 101km of standard fiber.

All-optical 3R regeneration and wavelength conversion in an integrated SOA/DFB laser: Experiment and simulation

The simultaneous all optical 3R regeneration and format conversion in a simple, single integrated device was examined. The integrated device consisted of a semiconductor optical fiber (SOA) monolithically integrated with a distributed feedback (DFB) laser. Gain saturation was employed for the transmission of a data signal regenerated all-optically in the laser/amplifier device. The regeneration of the electrically filtered eye diagrams was observed by noise removal and extinction ratio-improvement by the device.

All optical wavelength conversion at 2.488GBits/s using the integrated multi grating cavity (MGC) laser

A novel integrated Multi-Wavelength Grating Cavity (MGC) laser has been used for multi-channel wavelength conversion at 2.488Gbits/s. Functions demonstrated include conversion to multiple wavelengths, WDM multiplexing and 1×4 space switching.

Analysis and performance assessment of 6-pulse inverter-fed 3-phase and 6-phase induction machines

The paper describes a model for a 6-phase induction motor driven by an inverter operating in a 6-pulse (square wave) mode. The model is implemented and performance, in terms of torque, current, efficiency and pulsating torque, compared to the performance of a 3-phase motor (both sine and 6-pulse supplied). The models are verified experimentally, in particular the efficiency performance, and it is illustrated that the improvement in inverter efficiency when in 6-pulse operating mode may improve the performance of the overall system. © 2005 IEEE.

Power losses in small inverter-fed induction motors

This paper presents the results of experimental and simulation investigations of the breakdown of losses in a small inverter fed induction motor. Factors that are considered include the impact of skew, excitation voltage waveform shape and PWM switching frequency. Detailed finite element simulations of the motor performance are carried out for the various conditions, with simulation results compared to calorimetric test results. © 2005 IEEE.

Advanced DC link capacitor technology application for a stiff voltage-source inverter

Problem of DC link size in a stiff voltage-source inverter for electric drive is described in the paper. Advantages of advanced film capacitor technology over conventional one for DC link application are reviewed. Conventional DC link capacitor selection methods are questioned in view of advanced capacitor technology utilization in stiff voltage-source inverter. For capacitor selection maximum ripple rms current point is shown. DC link ripple current spectrum analysis under modern PWM techniques is presented. Some capacitor selection recommendations are given. The analysis has been aided greatly by computer modeling in PSpice. ©2005 IEEE.

Studies of inverter ratings of BDFM adjustable speed drive or generator systems

This paper discusses the inverter ratings of Brushless Doubly-Fed Machine (BDFM) adjustable speed drive (ASD) or generator (ASG) systems. Based on the per phase equivalent circuit model, the ratings of the two inverters in a bidirectional converter are evaluated individually. An approach to minimise the total inverter rating is presented, taking into account power factor constraints of the power grid. The effects of speed deviation and control winding excitation on the inverter ratings are discussed. Predictions of inverter ratings are presented with experimental verification. A design example is also provided in which the total inverter rating is minimised for a practical BDFM based ASG system. © 2005 IEEE.

An integrated approach to national marine resources development

A review is presented of the various marine resources and their potential, concerning fishing, aquaculture, transportation, pollution, hydrocarbons and solid minerals, renewable energy and ocean thermal energy conversion. Administrative problems confronting their rational management in Sri Lanka are examined, considering coastal area management and development, management issues, and alternatives.

Investigation and comparison of inverter-fed induction machine loss

This paper presents an investigation into the losses in a three-phase induction motor under different pulse width modulation (PWM) excitation conditions. The impacts of Sinusoidal PWM, Space Vector PWM and Discontinuous PWM on machine loss are compared and studied. Finite element analysis simulations are employed to predict the machine losses with the loss breakdown analysis under different PWM schemes. Direct Calorimetric measurements are utilized to verify the finite element modeling and provide direct quantifications of machine loss under modern PWM techniques. © 2008 IEEE.

A closely integrated digital image capture device for embedded applications

A modular image capture system with close integration to CCD cameras has been developed. The aim is to produce a system capable of integrating CCD sensor, image capture and image processing into a single compact unit. This close integration provides a direct mapping between CCD pixels and digital image pixels. The system has been interfaced to a digital signal processor board for the development and control of image processing tasks. These have included characterization and enhancement of noisy images from an intensified camera and measurement to subpixel resolutions. A highly compact form of the image capture system is in an advanced stage of development. This consists of a single FPGA device and a single VRAM providing a two chip image capturing system capable of being integrated into a CCD camera. A miniature compact PC has been developed using a novel modular interconnection technique, providing a processing unit in a three dimensional format highly suited to integration into a CCD camera unit. Work is under way to interface the compact capture system to the PC using this interconnection technique, combining CCD sensor, image capture and image processing into a single compact unit. ©2005 Copyright SPIE - The International Society for Optical Engineering.