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Background Pharmacists have an essential role to play in the NHS Long Term Plan. Hospital pharmacy departments need to develop novel roles to strengthen teams and improve patient care. In September 2017, Mid Yorkshire Hospitals NHS Trust appointed a consultant antimicrobial pharmacist along with an administrative apprentice to strengthen pharmacy and infection leadership and support the delivery of the antimicrobial resistance national targets. From January 2018 to June 2020, the infection team worked with locums but no substantive consultant microbiologists. Objectives To describe the benefits of developing novel pharmacy roles to strengthen an infection multidisciplinary team Methods A shortage of consultant microbiologists provided opportunities to develop and enhance other infection roles. These included one year of funding from Pathology for a Band 6 Specialist Pharmacy Technician. The role was subsequently funded by the Adult Community Services team to support the home intravenous antibiotic service. Senior support was provided by the Pathology Group Manager, Head of Infection Prevention and Control and Director of Pharmacy. The apprenticeship levy supported a Level 4 Data analyst qualification to develop the pharmacy administrator role. Two other infection roles were developed: Advanced Clinical Practitioner and Trainee Clinical Scientist, both of which could not be sustained for lack of adequate consultant microbiologist resources for clinical supervision within the team. Results The Specialist Pharmacy Technician coordinates the home intravenous antibiotic service. Clinical responsibility remains with the discharging consultant medical officer. The antimicrobial pharmacy team led the introduction of antibiotic elastomeric pumps for home use, saving 2500 inpatient bed days. Patient and staff feedback on the novel pharmacy roles has been positive. Band 5 Pharmacy Data Analyst – Antimicrobials responsibilities include clinical trial participation, data collection and analysis including ward level working, reporting and coordination of the audit programme. The role has enabled contribution to national research studies, including Antibiotic Review Kit (ARK-Hospital) and Procalcitonin: Evaluation of Antibiotic Use in COVID-19 Hospitalised Patients (PEACH). Through a new strategy, consultant microbiologist workforce has progressively grown back to three full time equivalents and a 4th post advertised, enabling an increase in participation in ward rounds, multidisciplinary team meetings, antimicrobial stewardship, infection prevention & control, Director of Infection Prevention and Control role and leading NIHR research trials. The consultant pharmacist remains in post as a senior leader, and also has a Trust role as Director of Innovation. This change provided funding for an increase from Band 3 to Band 5 data analyst, promotion of a senior Band 7 pharmacist to a Band 8a advanced clinical pharmacist, and conversion of a part time Band 7 pharmacist to a full-time role. Discussion An innovative approach to development of pharmacy, data, nurse and scientist roles has strengthened the infection service in a regional hospital and community services Trust. Pharmacy-led team meetings are now routine in the Trust allowing for more efficient use of consultant microbiologist time. Conclusions Potential future roles are further administrative support, pharmacy assistant, clinical nurse specialist – antimicrobials, and antimicrobial pharmacy team leader.

The present study was carried out to evaluate in-vitro toxicity associated with chitosan nanoparticles, poly(anhydride) nanoparticles and poly-lactide co-glycolide (PLG) microparticle in Vero cell line. The cytotoxicity of all three micro/nano-particles was assessed using different concentration. For each concentration, the confluent monolayer was treated for a period of 36-48 hours and studied for morphological alteration, live and death count etc. after the treatment. It was observed that the different concentrations of chitosan nanoparticles and Gantrez® nanoparticles did not have significant effect on the cell viability as evident from the non-significant difference between the OD540 of formazan product formed from MTT in treated and untreated cells. The concentration of chitosan nanoparticles and Gantrez® nanoparticles up to 1000 μg/ml did not have any influence in cellular metabolic activities and viability. However, a reduction in the cellular viability and metabolic activities were observed when PLG microparticles were used at 1000 μg/ml. At concentrations below 1000 μg/ml, all the nanoparticles/microparticles were found to be safe in terms of cytotoxicity.

In this paper, we show the effect of lateral external\ud optical feedback on an all semiconductor photonic crystal surface\ud emitting laser (PCSEL). Initially, a PCSEL is grown and fabricated\ud with a square lattice of triangles, the device is shown to\ud operate electrically driven at room temperature under continuous\ud wave condition. We investigate, theoretically and experimentally,\ud the effect of lateral feedback on the performance of photonic crystal\ud lasers. Demonstrating a reduction in mode competition and\ud a modification to spatial mode distribution, opening routes to all\ud electronic beam shaping and divergence control.

This paper presents an alternative, quasi-analytic method for evaluating the resonances of the 2-D photonic crystals (PCs) pertinent to Photonic Crystal Surface Emitting Lasers (PCSELs), based on viewing the 2-D periodic structure as discontinuities in a (periodic) multilayer waveguide. This method is easy to implement, computationally fast and can readily also compute structures of small number of periodicities.

The frequently sought after combination of characteristics in semiconductor lasers of high power together with narrow beam divergence and monochromatic output is usually difficult to attain. The photonic crystal surface emitting laser (PCSEL) is one category of device, however, which tends to provide the above-mentioned desirable output features. The PCSEL uses a large area optically active surface but with a two-dimensional periodic structure that enables it to generate high power in a narrow vertically emitted beam yet maintaining single wavelength operation. A primary requirement to model PCSELs is to obtain the optical field resonances that identify the lasing mode. This study presents an alternative method for evaluating the resonances, based essentially on the transfer-matrix technique and wave propagation in multilayer medium, which is relatively easy to formulate, and has quite modest demands on computing requirements.

In this paper we discuss the development of all-semiconductor photonic crystal surface emitting lasers. These devices offer novel routes to coherently coupled arrays which promise previously unachievable levels of brightness and a route to all-electronic beam steering from a single element device.

We present a novel semi-analytical method utilising modal index analysis, for modelling the field resonances of photonic crystal surface emitting lasers (PCSELs). This method shows very good agreement with other modelling techniques in terms of mode calculations, with the added advantages of computational simplicity, the calculation of threshold gain, and rapid analysis of finite structures. We are able to model the effect of external lateral feedback and simulations indicate that the near-field peak can be electronically displaced and the threshold as well as the frequency can be controlled through external in-plane feedback, paving the way to dynamic control of PCSELs.

The realization of a 1 × 2 coherently coupled photonic crystal surface emitting laser array is reported. New routes to power scaling are discussed and the electronic control of coherence is demonstrated.

This paper presents a new modal index analysis method for evaluating the resonances of PCSEL structures which is versatile, efficient and fast. Hence it is envisaged that the implementation of this method will enhance the potential to generate more comprehensive models of photonic crystal based devices, say, PCSELs, that include, for example, aspects of inversion population distribution and also time dependence while still retaining relatively modest demands on computational resources.

A terahertz (THz) antenna is proposed that offers high input resistance and gain in the presence of an electrically thick GaAs substrate. The antenna is centrally fed using two vertical probes connected to a photomixer on a thin low temperature grown gallium arsenide (LTG-GaAs) film which is supported by the GaAs substrate. An input impedance of ∼ 3.3 kΩ has been achieved using a dipole antenna that is printed on a thin dielectric slab, and isolated from the supporting substrate using a metal ground plane. A square aperture has been introduced to facilitate the illumination of the photomixer with two laser beams. Furthermore, a frequency selective surface (FSS) has been incorporated in the configuration, which results in a broadside gain of ∼ 19 dBi at a resonance frequency of 0.97 THz.

A mathematical model, based on cylindrical modes, capable of predicting the far-field angular emission pattern resulting from emission within cylindrical nanostructures is demonstrated and shown to yield self-consistent detailed numerical results. This method is much less computationally intensive than the prevailing finite-difference time-domain method and potentially provides more insight into the physics responsible for predictions. When considering the fundamental HE 11 mode in isolation, the emission intensity within 1° of the nanorod axis is shown to vary by 10% as the separation δ z between quantum wells is varied. Some of the modes can be shown to correspond with features observed in experimental emission patterns obtained by angular photoluminescence.

We investigate the beam divergence in far-field region, diffraction loss and optical confinement factors of all-semiconductor and void-semiconductor photonic-crystal surface-emitting lasers (PCSELs), containing either InGaP/GaAs or InGaP/air photonic crystals using a three-dimensional FDTD model. We explore the impact of changing the PC hole shape, size, and lattice structure in addition to the choice of all-semiconductor or void-semiconductor designs. We discuss the determination of the threshold gain from the diffraction losses, and explore limitations to direct modulation of the PCSEL. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

980 nm GaAs-based photonic crystal surface emitting lasers containing all semiconductor GaAs/InGaP and GaAs/air photonic crystals (PC) inside their cavity are theoretically investigated. We use a combination of an average index approach and optical coupled mode theory to optimize the PC interaction with optical modes of the laser waveguide and draw guidelines for design of PCSELs based on a range of material systems and operating wavelengths. Results show that the all-semiconductor PC provides a higher coupling with the optical mode in most cases.

A convenient, iterative method for determining injection current generated two-dimensional carrier distributions, and consequent control of refractive index profiles, in optical guided-wave devices is presented. This method is "user-friendly" and readily adaptable to a large variety of materials and geometries. It is particularly useful for a quick and quite accurate assessment of the feasibility of operation of novel device structures. Results obtained by this quasianalytic method are shown to agree very favorably with those obtained from more general but far more complicated commercially available software.

Waveguides optimised at 1.5 μm have been fabricated from erbium-doped Smart Cut® silicon-on-insulator wafers. The wafers were implanted at 1 MeV with a low dose of Er, chosen to minimize structural damage to the layers and reduce the need for prolonged thermal treatment. Single mode rib waveguides were designed using the very thin Si top layer (1.5 μm) of the wafers and the buried silicon dioxide layer of thickness 3 μm. Near field measurements of the lateral and vertical confinement show a single, symmetric, and well-confined optical mode. As predicted in the literature, when the Er is in the waveguiding region itself, the measured waveguide losses increase. This is attributed to the implant-induced damage, which is observed as a broad defect peak in photoluminescence (PL) prior to any annealing. After annealing, sharp luminescence from the erbium appears and the broad PL peak has been removed. Loss measurements reveal that the losses decrease but are still slightly worse than the losses measured for undoped-waveguides.

A large optical cavity diode laser has been developed operating at 1070 and 1118 nm using partially strain-balanced DQW gain regions of GaAs 0.94 P 0.06 /In x Ga 1-x As (x = 0.24 and 0.29). TEM has been used to characterise the QWs for interface roughening resulting from the high residual compressive strain. For both wavelengths, oxide-defined stripe-contact devices show comparable slope efficiencies and T 0 values. In the case of the 1070 nm laser, the operating lifetime at 15 C was in excess of 4600h for an output of 1.5 W and degradation rate of 2 × 10 5 /h.

We investigated the beam divergence in far-field region, diffraction loss and optical confinement factors of semiconductor photonic crystal surface emitting lasers containing either InGaP/GaAs or InGaP/air photonic crystals. The maximum in-plane feedback in PCSELs with InGaP/GaAs PCs has been observed at the ratio between PC atom radius and the lattice constant of 0.2 and 0.38. The surface emission grows as the size of atom increases.

In the work reported here we use the finite-difference time-domain method to model an ordered nanorod array incorporated in a vertical LED structure in place of the surface roughened region. The simulations reveal that diffraction dominates the far field emission when the emissive layer lies below the nanorod array, as might occur in a vertical LED structure with the NR layer used as a light extracting element in place of a roughened surface.

This paper presents a fast and accurate quasi-analytic model for studying optical field propagation in weakly guiding dielectric structures. The proposed efficient and versatile computational scheme is obtained by merging the Hermite-Gauss (HG) total field expansion with the numerical collocation method and is particularly suited for longitudinally nonuniform structures. By means of a quasilinearization scheme, the same procedure has also been successfully applied to the analysis of field propagation in Kerr-nonlinear media. The latter achievement gives an indication of the great potentialities offered by this straight forward method. Several examples are discussed in the paper and in all cases the results computed by the proposed method favorably compare with those from alternative methods.

A new type of vertical-cavity surface-emitting laser (VCSEL) is proposed and analyzed to show the possibility of optical pumping from an integrated edge-emitting laser. With this scheme, it may be possible to make VCSEL's of very small dimensions and VCSEL arrays. The laser design utilizes dopant induced intermixing of quantum wells (QW's) to provide different gain regions for the surface and edge-emitting sections. The multimode rate equations are used to evaluate the possibility of such a laser and the roles of the various design parameters are discussed. It is seen that efficient surface photon emission is possible for high vertical-cavity mirror reflectivities and sufficient separation of bandgap energies for the two QW gain regions.

The planar multilayer dielectric structure (PMLS) has been used as a model for large diameter vertical cavity surface emitting lasers, to analyse the vertical and in-plane components of spontaneous emission (SE). Both /spl lambda/ and /spl lambda//2 cavities have been considered. Calculations show a high level of in-plane SE for both cases. The results are discussed in the context of recent experimental measurements of in-plane emission in VCSELs.

The guiding properties of passive tapered rib-waveguides with a large output aperture have been measured as a function of both rib-height and taper angle in the context of high power semiconductor optical sources. It is observed that the near-field (intensity) distribution at the output aperture can be much narrower than that expected from just the fundamental mode of the waveguide at that plane. A theoretical model of the structure, based on the step-transition approximation, has been developed to analyse experimentally measured near-field profiles. The experimental and theoretical results are found to be in good agreement over a wide range of taper angles and other waveguide parameters. Also presented are the corresponding far-field patterns which are so pertinent to high power device design.

Measurements of light emission from GaN nanorods of diameter between 80 and 350 nm, containing either a three-well multiple InGaN quantum well or a single quantum well, have been performed by photoluminescence (PL) and cathodoluminescence (CL) hyperspectral imaging. The PL underwent a Stark shift to the blue as the nanorod diameter was reduced, indicating substantial relaxation of the compressive strain in the quantum wells. The intensity of the nanorod emission per unit area can exceed that of the planar starting material. The CL measurements revealed that the wavelength of the quantum well emission varied with radial position in the nanorod. Simulations by a modal expansion method revealed that the light extraction efficiency varies with radial position and the variation is dependent on nanorod diameter. Finite difference time domain simulations showed that Bloch mode formation in the buffer layer below the nanorods impacts on the light extraction.

The dynamical evolution of polarization states in vertical-cavity surface-emitting lasers (VCSELs) and ridge-waveguide edge-emitting laser diodes (RWEELD) has been studied, taking into account the interplay between the mode structure and the gain medium. The role of spatial hole burning in determining polarization switching properties of both device geometries is demonstrated.

‘In-plane’ superluminescence (IPSL) in VCSELs is analysed in the framework of the ray approximation. The results show that, for typical geometry and dimensions of vertical-cavity surface-emitting lasers, the IPSL can play an important role and may lead to significant additional losses (referred to vertical lasing) of pump power for large diameter devices (10–100 µm). It is found that, for AlAS/GaAs device diameters in excess of about 50 µm, the IPLS can become sufficiently large such that lasing along the radius may result.

This special issue ofOptical andQuantumElectronics contains a selection of papers that were presented at the 13th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) in Vancouver, Canada, August 19–22 2013. NUSOD’13 was chaired by Lukas Chrostowski from the University of British Columbia, Canada and Joachim Piprek, NUSOD Institute, USA. The purpose of the NUSOD Conference is to provide a forum for scientists from research labs around the world to discuss the recent advances in the modelling of optoelectronic devices. This year the main topics included numerical modelling of light emitting diodes, photo-detectors, photonic crystal fibres, propagation of ultra-short optical pulses, photovoltaic and optical integrated devices. The papers collected in this special issue of Optical and Quantum Electronics provide a comprehensive representation of the topics discussed at the conference. The editorswish to thank all contributing authors for careful preparation of themanuscripts and the reviewers for their work and timely response. We now look forward to NUSOD’14 that will take place in Palma de Mallorca, Spain, September 1–4, 2014.

A theoretical treatment of the propagation of optical signals through semiconductor travelling wave amplifiers (TWAs) is presented. Analytic solutions are obtained for the temporal behaviour of the output for amplifiers subject to input signals composed of an exponentially varying small signal superimposed on a large time-independent signal. The formulation includes the spontaneous recombination term and the line-width enhancement (anti-guiding) factor. The solution obtained may be readily interpreted as a combined amplitude and phase modulated output signal. The analysis also clearly reveals the combined effects of the spontaneous recombination rate and the time constant of the exponentially varying input signal. In this way a total description of the response of the optical amplifier is obtained.

Three techniques for the self-consistent solution of the diffusion equation, which describes the distribution of carriers in semiconductor lasers and optical amplifiers, and the EM wave equation have been investigated. The relative merits of a Jacobian tri-diagonal technique, a perturbation approach and a transfer matrix method are identified.

Calculations have been performed of transverse mode competition during the turn-on transient of VCSELs. Taking account of the interplay between the transverse mode structure and the gain medium it is shown that the spatial holeburning plays an important role in determining which transverse mode will be sustained under steady-state operating conditions.

Calculations are reported of the dynamic evolution of transverse modes in vertical cavity surface emitting lasers (VCSEL's). It is shown that the spatial distribution of the modal fields plays an important role in determining the steady-state operating characteristics of the device. It is found that spatially separated modes can coexist by sharing the available gain, whereas strong competition occurs between modes that have a strong spatial overlap. The influence of carrier diffusion and spatial holeburning during the turn-on transient of the laser is elucidated, and the implications for the steady-state modal properties of the device are indicated. >

We report a broadband-gain superluminescent diode (SLD) based on self-assembled InAs quantum dots (QDs) for application in a high-resolution optical coherence tomography (OCT) light source. Four InAs QD layers, with sequentially shifted emission wavelengths achieved by varying the thickness of the In0.2Ga0.8As strain-reducing capping layers, were embedded in a conventional p-n heterojunction comprising GaAs and AlGaAs layers. A ridge-type waveguide with segmented contacts was formed on the grown wafer, and an as-cleaved 4-mm-long chip (QD-SLD) was prepared. The segmented contacts were effective in applying a high injection current density to the QDs and obtaining emission from excited states of the QDs, resulting in an extension of the bandwidth of the electroluminescence spectrum. In addition, gain spectra deduced with the segmented contacts indicated a broadband smooth positive gain region spanning 160 nm. Furthermore, OCT imaging with the fabricated QD-SLD was performed, and OCT images with an axial resolution of ∼4 μm in air were obtained. These results demonstrate the effectiveness of the QD-SLD with segmented contacts as a high-resolution OCT light source.

Large Q-factor resonators are essential components in most electronic and photonic systems; that requirement is even more pertinent to the next generation of highly compact nano-photonic integrated circuits. Surface-Plasmon waves combined with Whispering-Gallery modes have the potential to satisfy the dual requirements of small geometry and large Q. A quasi-analytic formulation for SPWG large Q resonator modes is presented in this paper and is demonstrated to be a convenient yet satisfactory procedure to compute device characteristics. © 2011 IEEE.

In the above paper [1] , there was a minor error in the implementation of the transfer matrix method used to calculate the complex reflection coefficient \(r_{\mathrm {-}}\) of the nanorod/GaN/sapphire trilayer. The formulas provided by Hecht [2] use the convention, where the phase of the electromagnetic fields is assumed to vary as e \(^{\mathrm {i}(\omega t\mathrm {-}\beta z)}\) as opposed to the convention used in the rest of the work where the phase varies as e \(^{\mathrm {i}(\beta z \mathrm {-}\omega t )}\) . While this inconsistency has affected the results reported in [1, Figs. 5–9] , the authors believe the conclusions drawn from these data are unchanged.

Research efforts into Surface Acoustic Waves (SAW) devices built on III‐Nitrides has recently significantly intensified because of the increasing availability of good‐quality epitaxial material. Owing to their strong piezoelectricity and high acoustic velocity, high‐Al‐content materials are of particular interest in high‐speed applications (GHz electronics). For optoelectronics applications III‐Nitrides cover a wide range of wavelengths from ultra‐violet (AlN) to blue (GaN) to infra‐red (InN); thus providing great flexibility in the choice of operating wavelength. III‐Nitrides, therefore, become particularly attractive for the development of acousto‐optic modulators where the SAW is used to create a controllable (moving) optical grating, causing the diffraction of the Optical Guided Wave (OGW). The interaction is governed by the momentum and energy conservation and importantly by the field overlap of the two waves. We present here design guidelines and modelling results for the development of III‐Nitride‐...

A superluminescent diode monolithically integrated with a surface acoustic wave Bragg-cell to operate as a beam deflector is proposed. The analysis procedures for determining the acoustic and optical modes, and modal diffraction of the optical beam are employed to develop a practical model for the integrated device. Results from this model are used to assess the operational characteristics of the proposed integrated device and to provide design guidelines.

The characteristics of surface plasmon wave (SPW) modes supported by multiple layer configurations are analysed in this paper. The transmission-line analysis based on the transverse resonance condition is implemented to describe SPW excitation via a prism coupler. This accurate yet convenient modeling technique is also applied to investigate the characteristics of SPWs in multilayer media with optical gain as a means of reducing/overcoming the typical, undesirably large loss associated with SPWs in conventional structures. The paper will also present experimental and theoretical results to quantify the operational characteristics to be expected from prism coupled SPW sensors that use semiconductor optical sources.

Superluminescent Diodes are high power semiconductor optical sources with relatively broad spectral linewidth used for a variety of applications. The basic, crucial device feature needed to achieve high-power superluminescent operation is low facet reflectivity to prevent lasing and optical gain saturation. Theoretical calculations show that by appropriately designing the device length and output facet reflectivity a significant increase in optical output power and wall-plug efficiency can be obtained. This paper presents theoretical and preliminary experimental results indicating that it is possible to further improve the operational characteristics of superluminescent diodes and achieve high optical output power with high conversion efficiency. The control of the facet reflectivity and the overall device optical geometry are obtained by using Focused Ion Beam post-fabrication processing. Results obtained from the characterisation of superluminescent diodes before and after facet reflectivity alteration achieved by creating patterns on the subwavelength scale will be discussed.

In this paper, airy functions to represent Bessel functions of large index order are applied. The eigenvalue wave equation is then reduced to a polynomial equation. The complex roots of such a polynomial are the sought whispering gallery modes (WGM) resonant frequencies which in effect, provide the Q-factors and determine the WGM field profiles. Particular emphasis has been given to deriving the spectral and spatial distribution of WGMs, along the Q-factors of the resonators. These properties are essential to characterise circular semiconductor lasers, which use WGMs as modal emission.

Strained In0.21Ga0.79As/GaAs quantum well structures have been grown by molecular beam epitaxy on (111)B GaAs substrates. Well widths between 20 and 160 A, separated by 500 A barriers were grown sequentially on the same substrate and subsequently characterized by low‐temperature (10 K) photoluminescence. The variation of the e‐hh transition energy with well width is markedly different for samples grown simultaneously on (100) and (111)B substrates due to the strain induced piezoelectric field. Using the envelope function approximation, the dependence of n=1 e‐hh transitions of (111)B samples on well width can be interpreted by the presence of a built‐in electric field of magnitude of 1.45×107 V/m. In contrast to the (100) sample, exciton lifetimes in the (111)B sample depend strongly on well width because of spatial separation of electrons and holes in the triangular wells. In the 160 A well, the exciton lifetime increases to 755 ns corresponding to a reduction of about three orders of magnitude in the electron‐hole wave function overlap integral.

We present a new model to analyze the spatial characteristics of the output beam of conventional (straight-stripe) and tapered superluminescent light-emitting diodes. The device model includes both spontaneous and stimulated emission processes as well as a nonuniform carrier density distribution to correctly represent current spreading and carrier diffusion effects. Near- and far-field intensity profiles computed with this model are accurately verified over a wide range of injection currents by comparisons with experimental results measured from in-house fabricated devices. (C) 2003 Optical Society of America.

A quasi-analytic formulation based on Laguerre-Gauss functions (LG-Fs) that appears to be suitable to analyse vertical-cavity surface-emitting lasers (VCSELs) is described. The paper focuses on demonstrating the attractive feature of LG-Fs; in solving for optical field propagation in both diffracting type and guided-wave type configurations, which is particularly advantageous for modelling present-day VCSELs. The paper also outlines the LG-F expansion formalism to solve for both the optical field and the carrier density distribution to achieve a self-consistent VCSEL model.

Optical sources that combine high power with high brightness are in great demand for various applications. Although sophisticated device designs have been demonstrated to have such desirable characteristics, to contain the device costs tapered geometry devices seem to provide attractive alternatives. Further, particularly for high-power operation, the bow-tie configuration is effective for further reducing the risk of catastrophic optical damage and for obtaining a good quality output beam. The authors present the detailed analysis that has been necessary to optimise both the material layer structure and the tapered laser geometry to achieve simultaneously high power and high brightness. Following the design guidelines, several 980 nm parabolic bow-tie lasers have been fabricated and characterised in-house, obtaining output powers in excess of 700 mW per facet in a diffraction-limited (2.7°) beam measured without the use of external lenses.

Semiconductor optical sources that provide high power in a diffraction-limited beam (high brightness) are required for various applications, such as fibre amplifier pump sources, free-space links, dentistry, materials processing. The two most important issues that must be considered in the design of high-power high-brightness semiconductor (S/C) optical sources are catastrophic optical damage (COD) and filamentation of the optical field. Hence, it is indispensable to accurately design both the S/C multilayer material structure and the geometry of the laser cavity to achieve the desired operational characteristics. In addition, device manufacturing costs, packaging complexity (e.g., expensive external micro-optics systems) and tolerance constraints are significant features that have to be taken into account for future device developments. © 2003 IEEE.

A compact model for tapered-geometry optical sources has been developed using perturbation analysis to evaluate carrier-induced changes to modal propagation constants. Results for novel, parabolically-tapered devices demonstrate their merit as high-power semiconductor laser sources.

We present a detailed analysis of the output beam of high-power edge-emitting angled tapered super-luminescent LEDs (A-TSLEDs). A device model, including spontaneous and stimulated emission processes as well as, the typical nonuniform carrier-density distribution due to current spreading and carrier diffusion, has been developed and used to interpret the experimentally obtained characteristics of inhouse-fabricated A-TSLEDs. The good match between measured and theoretical results indicates that the model reproduces the A-TSLED operation very satisfactorily and clearly explains the role of the collecting lens on the pronounced asymmetry of some of the measured optical intensity profiles. (C) 2002 Optical Society of America.

A broadband multi-mode output with optical frequency bandwidth of several THz has been obtained by a method of modulating a two-section semiconductor laser (TSL). The comb-of-modes output can be systematically varied in bandwidth and opens up a new range of applications for TSLs.