A novel extremely broadband superluminescent diode based on symmetric graded tensile-strained bulk InGaAs

A novel broadband superluminescent diode (SLD), which has a symmetric graded tensile-strained bulk InGaAs active region, is developed. The symmetric-graded tensile-strained bulk InGaAs is achieved by changing the group III TMGa source flow only during its growth process by low-pressure metalorganic vapor-phase epitaxy (LP-MOVPE), in which the much different tensile strain is introduced simultaneously. At 200mA injection current, the full width at half maximum (FWHM) of the emission spectrum of the SLID can be up to 122nm, covering the range of 1508-1630nm, and the output power is 11.5mW.

Unselective regrowth buried heterostructure long-wavelength superluminescent diode realized with MOVPE

A novel unselective regrowth buried heterostructure (BH) long-wavelength superluminescent diode (SLD), which has a grade-strained bulk InGaAs active region, was developed by metalorganic vapor-phase epitaxy (MOVPE). The 3 dB emission spectrum bandwidth of the SLD is about 65 nm with the range from 1596 to 1661 nm at 90 mA and front 1585 to 1650 nm at 150 mA. An output power of 3.5 mW is obtained at 200 mA injection current under CW operation at room temperature. (c) 2006 Elsevier B.V. All rights reserved.

Quantum-dot superluminescent diode: A proposal for an ultra-wide output spectrum

We propose a novel superluminescent diode (SLD) with a quantum dot (QD) active layer, which should give a wider output spectrum than a conventional quantum well SLD. The device makes use of inhomogeneous broadness of gain spectrum resulting from size inhomogeneity of self-assembled quantum dots grown by Stranski-Krastanow mode. Taking a design made out in the InxGa1-xAs/GaAs system for example, the spectrum characteristics of the device are simulated realistically, 100-200 nm full width of half maximum of output spectrum can be obtained. The dependence of the output spectrum on In composition, size distribution and injection current of the dots active region is also elaborated.

Superluminescent diode monolithically integrated with novel Y-branch by bundle integrated waveguide for fiber optic gyroscope - art. no. 68380D

We have developed a novel InP-based, ridge-waveguide photonic integrated circuit (PIC), which consists of a 1.1-um wavelength Y-branch optical waveguide with low loss and improved far field pattern and a 1.3-um wavelength strained InGaAsP-InP multiple quantum-well superluminescent diode, with bundle integrated guide (BIG) as the scheme for monolithic integration. The simulations of BIG and Y-branches show low losses and improved far-field patterns, based on the beam propagation method (BPM). The amplified spontaneous emission of the device is up to 10 mW at 120 mA with no threshold and saturation. Spectral characteristics of about 30 nm width and less than I dB modulation are achieved using the built-in anti-lasing ability of Y-branch. The beam divergence angles in horizontal and vertical directions are optimized to as small as 12 degrees x8 degrees, resulting in good fiber coupling. The compactness, simplicity in fabrication, good superluminescent performance, low transmission loss and estimated low coupling loss prove the BIG and Y-branch method to be a feasible way for integration and make the photonic integrated circuit of Y-branch and superluminescent diode an promising candidate for transmitter and transceiver used in fiber optic gyroscope.

A Broadband Long-Wavelength Superluminescent Diode Based on Graded Composition Bulk InGaAs

A novel unselective regrowth buried heterostructure long-wavelength superluminescent diode （SLD） with a graded composition bulk InGaAs active region is developed by metalorganic vapor phase epitaxy （MOVPE）. At a 150mA injection current, the full width at half maximum of the emission spectrum of the SLD is about 72nm, ranging from 1602 to 1674nm. The emission spectrum is smooth and flat. The ripple of the spectrum is less than 0.3dB at any wavelength from 1550 to 1700nm. An output power of 4.3mW is obtained at a 200mA injection current under continuous-wave operation at room temperature. This device is suitable for the applications of light sources for gas detectors and L-band optical fiber communications.

Graded tensile-strained bulk InGaAs/InP superluminescent diode with very wide emission spectrum

A kind of novel broad-band superluminescent diodes (SLDs) using graded tensile-strained bulk InGaAs is developed. The graded tensile-strained bulk InGaAs is obtained by changing only group-III trimethyl-gallium source flow during low-pressure metal organic vapor-phase epitaxy. At the injection current of 200 mA, the fabricated SLDs with such structure demonstrate full-width at half-maximum spectral width of 106 nm and the output light power of 13.6 mW, respectively.

The effect of proton radiation on a superlumine scent diode (SLD)

The effect of proton radiation on a superluminescent diode (SLD) was studied, and the radiation damage from different energies was compared. The results reveal that the optical power degradation is greater from 350 KeV protons than from 1 MeV protons. Analysis of SLD characteristics after irradiation shows that the main effect of radiation is damage within the active region. At the same time, the results also show that quantum-well (QW) SLDs are far less sensitive to radiation than double-heterojunction (DH) SLDs. (C) 2007 Elsevier B.V. All rights reserved.

Monolithically integrated transceiver with novel Y-branch by bundle integrated waveguide for fibre optic gyroscope

A novel Y-branch based monolithic transceiver with a superluminescent diode and a waveguide photodiode (Y-SDL-PD) is designed and fabricated by the method of bundle integrated waveguide (BIG) as the scheme for monolithic integration and angled Y-branch as the passive bi-directional waveguide. The simulations of BIG and Y-branches show low losses and improved far-field patterns, based on the beam propagation method (BPM). The amplified spontaneous emission of the device is up to 10mW at 120mA with no threshold and saturation. Spectral characteristics of about 30 nm width and less than 1 dB modulation are achieved using the built-in anti-lasing ability of Y-branch. The beam divergence angles in horizontal and vertical directions are optimized to as small as 12 degrees x 8 degrees, resulting in good fibre coupling.

First in-vivo trials of a fibre Bragg grating based temperature profiling system

We describe the results of in-vivo trials of a portable fiber Bragg grating based temperature profile monitoring system. The probe incorporates five Bragg gratings along a single fiber and prevents the gratings from being strained. Illumination is provided by a superluminescent diode, and a miniature CCD based spectrometer is used for demultiplexing. The CCD signal is read into a portable computer through a small A/D interface; the computer then calculates the positions of the center wavelengths of the Bragg gratings, providing a resolution of 0.2°C. Tests were carried out on rabbits undergoing hyperthermia treatment of the kidney and liver via inductive heating of metallic implants and comparison was made with a commercial Fluoroptic thermometry system.

First in-vivo trials of a fibre Bragg grating based temperature profiling system

We describe the results of in-vivo trials of a portable fiber Bragg grating based temperature profile monitoring system. The probe incorporates five Bragg gratings along a single fiber and prevents the gratings from being strained. Illumination is provided by a superluminescent diode, and a miniature CCD based spectrometer is used for demultiplexing. The CCD signal is read into a portable computer through a small A/D interface; the computer then calculates the positions of the center wavelengths of the Bragg gratings, providing a resolution of 0.2 °C. Tests were carried out on rabbits undergoing hyperthermia treatment of the kidney and liver via inductive heating of metallic implants and comparison was made with a commercial Fluoroptic thermometry system.

High-performance quantum-dot superluminescent diodes

By inclining the injection stripe of a multiple layer stacked self-assembled InAs quantum dot (SAQD) laser diode structure of 6degrees with respect to the facets, high-power and broad-band superluminescent diodes (SLDs) have been fabricated. It indicates that high-performance SLD could be easily realized by using SAQD as the active region.

EMI issues in high power and high level diode-clamped converters

Planar busbar is a good candidate to reduce interconnection inductance in high power inverters compared with cables. However, power switching components with fast switching combined with hard switched-converters produce high di/dt during turn off time and busbar stray inductance then becomes an important issue which creates overvoltage. It is necessary to keep the busbar stray inductance as low as possible to decrease overvoltage and Electromagnetic Interference (EMI) noise. In this paper, the effect of different transient current loops on busbar physical structure of the high-voltage high-level diode-clamped converters will be highlighted. Design considerations of proper planar busbar will also be presented to optimise the overall design of diode-clamped converters.

Asymmetrical DC link voltage configuration for a diode-clamped inverter

There is a trade off between a number of output voltage levels and the reliability and efficiency of a multilevel converter. A new configuration of diode-clamped multilevel inverters with a different combination of DC link capacitors voltage has been proposed in this paper. Two different symmetrical and asymmetrical unequal arrangements for a four-level diode-clamped inverter have been compared, in order to find an optimum arrangement with lower switching losses and optimised output voltage quality. The simulation and hardware results for a four-level inverter show that the asymmetrical configuration can obtain more output voltage levels with the same number of components compared with a conventional four-level inverter and this will lead to the reduction of the harmonic content of the output voltage. A new family of multi-output DC-DC converters with a simple control strategy has been utilised as a front-end converter to supply the DC link capacitor voltages for the optimised configuration.

Multi-output DC-DC converters based on diode-clamped converters configuration : topology and control strategy

This paper presents a new DC-DC Multi-Output Boost (MOB) converter which can share its total output between different series of output voltages for low and high power applications. This configuration can be utilised instead of several single output power supplies. This is a compatible topology for a diode-clamed inverter in the grid connection systems, where boosting low rectified output-voltage and series DC link capacitors is required. To verify the proposed topology, steady state and dynamic analysis of a MOB converter are examined. A simple control strategy has been proposed to demonstrate the performance of the proposed topology for a double-output boost converter. The topology and its control strategy can easily be extended to offer multiple outputs. Simulation and experimental results are presented to show the validity of the control strategy for the proposed converter.