J. Rorison

• University of Bristol

We present a theoretical analysis of highly-strained InAs quantum well lasers grown on InP for use in next-generation hollow-core fibre optical communications close to 2 µm, and validate our calculations against recent experimental data.

We theoretically analyse strain-compensated GaAs 1−x Bi x /GaN y As 1−y "W-type" quantum wells, demonstrating a viable approach to achieve efficient GaAs-based 1.3 and 1.55 µm lasers in which non-radiative Auger recombination is expected to be mitigated by type-II band offsets.

The calculation of material gain and performance characteristics for compound III‐V semiconductor quantum well lasers have been developed incorporating various approximations for the band structure. As the accuracy and the sophistication of the band structure is increased the computational time and mathematical complexity rises accordingly. This ar...

We theoretically analyse strain-compensated GaAs 1 −x Bi x /GaN y As 1 −y “W-type” quantum wells, demonstrating a viable approach to achieve efficient GaAs-based 1.3 and 1.55 µ m lasers in which non-radiative Auger recombination is expected to be mitigated by type-II band offsets.

Analysis of the broadband gain of a GaInNAs single quantum well (QW) semiconductor optical amplifier (SOA) is developed considering the tuneability of the gain in detail. The SOA is analyzed as a single device multiwavelength channel amplifier in a wavelength-division-multiplexing (WDM) network. The gain model includes the QW material gain derived...

We investigate the reflection spectra of distributed Bragg reflectors (DBRs) and DBR cavities with and without photonic crystal holes fabricated within them. A finite-difference time domain (FDTD) electromagnetic model which is considered to provide the exact solution of Maxwell equations is used as a reference model. Two simplified modelling appro...

Monte Carlo has become a powerful tool for describing complex systems with many degrees of freedom. It involves simulating a combination of deterministic and stochastic processes. Here, after a basic introduction to the technique, we focus on its application in the analysis of carrier transport in semiconductors. This method is applied to GaAs and...

Automatic parallelism, a subject of basic computer science research with the ability to solve large problems by scaling computer programs to run on multicore workstations, clusters, grids, and clouds, is helping engineers gain research and competitive advantages. The key requirements for a parallel computing environment include scalability and port...

We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24 dB) cavity reduces the current-induced shift d ¿/ dI of the principal peak in the RF spectrum (the effective pulse repe...

Using a many impurity Anderson model, we describe the interaction of localized N states with GaInAs conduction states. N dependent DOS and material gain reflect features from strong mixing with N pairs/clusters,suggesting its broadband tunability.

This work presents results of theoretical study of semiconductor vertical-cavity surface-emitting lasers (VCSELs) with two-dimensional photonic crystal (PC) waveguide incorporated into laser cavity. The model is designed for the understanding and optimization of VCSELs with incorporated PCs. Static and dynamic characteristics were investigated. It...

Using self energy calculations we present an improved band-anti crossing model with regards to the perturbed extended and localized states, based on the many impurity Anderson model. We also derive the perturbed density of states.

We have used the stochastic Monte-Carlo method to determine the carrier transport studies in the bulk GaInNAs material. We have incorporated phonon and impurity scattering processes and explicitly considered the role of the nitrogen impurities as scattering centers. We show that in the expression of the relaxation times it is the perturbed rather t...

The role of the single-N impurity in the GaInNAs system is evaluated using the single impurity Anderson model. The N impurities can act either as scattering resonances or as bound states depending on their energy position. For the former case, using self-energy calculations and Matsubara Green's functions we investigate the nature of the mixed sing...

An analysis of GaInNAs for optoelectronic device applications is performed. Design rules are provided for GaInNAs lasers in terms of laser parameters such as material gain, differential gain, differential refractive index, and linewidth enhancement factor. The study is extended to semiconductor optical amplifiers whose basic properties are investig...

Focused ion beam etching (FIB) was used to fabricate a two dimensional photonic crystal (PC)into the top distributed Bragg reflector (DBR) of an oxide-confined vertical-cavity surface-emitting laser (VCSEL) to create a PC-VCSEL. The influence of the geometrical parameters of the PC such as its lattice constant, the diameter and the depth of holes o...

Barium strontium titanate (Ba0.05Sr0.95TiO3) ferroelectric thin films have been prepared on single crystal [001] MgO substrates using the pulsed laser deposition method. The X-ray diffraction (XRD) analysis show the films were oriented with the [001] direction perpendicular to the plane of the substrate. The refractive index of Ba0.05Sr0.95TiO3 is...

The finite-difference time-domain (FDTD) and frequency-domain finite-element (FE) methods are used to study chirped pulse propagation in 2D photonic crystal (PhC) waveguides. Chirped pulse FDTD has been implemented, which allows the study of pulse propagation in a direct way. The carrier wavelength of the pulse is swept across the bandwidth of a mi...

Round-robin measurements on the linewidth enhancement factor are carried out within several laboratories participating to EU COST 288 action. The alpha-factor is measured by applying up to 7 different techniques. The obtained results are compared.

CLEO-Europe topic CB " Semiconductor Lasers ", oral session CB9 " Semiconductor laser physics " [CB9-2-WED]

In this proceedings the Finite Difference Time Domain (FDTD) and frequency domain Finite Element (FE) methods are used to model both linear chirped pulse and arbitrary chirped pulse propagation in 2D Photonic Crystal (PhC) waveguides. An in-house FDTD code has been implemented which allows the study of pulse propagation in a very direct way. The ca...

In this paper, an arbitrary chirped pulse (ACP)-finite difference time domain (FDTD) method is developed where pulse data can be read in from a data file. This has allowed the FDTD code to be used in combination with a semiconductor optical amplifier (SOA) model to study 2R regeneration using 2D photonic crystal waveguide for sub-picosecond pulses

The three-dimensional finite-difference time-domain method is used to obtain loss per unit length in a two-dimensional photonic crystal membrane waveguide by simulating three different length guides. Results are shown for propagation both above and below the light line. The results are compared with a Fourier expansion method and good agreement is...

This paper deals with the characterization of the differential carrier lifetime and the calculation of the monomolecular, radiative and non-radiative recombination coefficients and their temperature dependence as an evidence of the excellent temperature performance of this material system. The device characterized is a 1.25 μm GaInNAs laser structu...

A detailed experimental temperature study of single quantum-well GaInNAs lasers at room temperature and above has been carried out. Experimental results of L-I, T0, temperature dependence of lasing wavelength, optical gain and efficiencies are presented, discussed and compared with other materials. The temperature ranges studied is appropriate for...

The 3D finite difference time domain (FDTD) method is used to obtain the loss per unit length in a 2D photonic crystal membrane waveguide by simulating three different length guides. Results are shown for propagation both above and below the light-line. The results are compared with a Fourier expansion method and good agreement is obtained above an...

The FDTD method is used to study chirped pulse propagation in photonic crystal waveguides. In particular the carrier wavelength of the pulse is swept across the bandwidth of a mini-stopband feature and interesting, nonstandard pulse compression behaviour is observed. To further study this, increased frequency resolution across the MSB feature is us...

Novel modulation format using single push-pull Mach-Zehnder (MZ) modulator for high-speed transmission is proposed. Better or comparable performance with carrier-suppressed RZ is found. The simultaneous intensity modulation and differential phase-shift keying scheme using single MZ modulator is proposed too.

The integration of a low cost VCSEL with a microstrip antenna results in a low cost wireless-optical transmitter. The VCSEL impedance is matched to that of the antenna and initial microwave link results are shown

A novel balanced detection scheme for multi-access interference cancellation in multimedia spectral-amplitude-coding optical code-division multiple-access system is proposed. The receiver is capable of handling both equal and unequal in-phase cross correlation of optical orthogonal codes. A novel class of constant-length variable-weight optical ort...

A novel class of constant-length variable-weight optical orthogonal codes is proposed with good correlation properties suitable to support multimedia services with different data rates and quality-of-service requirements. The construction is based on the pairwise balanced designs.

A novel class of constant-length variable-weight optical orthogonal codes is proposed that can support multimedia services with different data rates and quality-of-service requirements. The construction is based on the pairwise balanced designs, or more specifically, on an incidence structure defined on an integer lattice. Proposed codes are suitab...

First Page of the Article

© 2003 Optical Society of America

We report for the first time the transmission of a 2.5-Gb/s SCM channel over a 300-m length of installed-grade 62.5-/spl mu/m core-diameter multimode fiber. This result demonstrates that, in a "worst-case" scenario, subcarrier modulation can be successfully used to allow improved quality transmission over multimode fiber links compared with convent...

Summary form only given. There has been a significant amount of study world-wide on etching PBG structures into both VCSELs and edge-emitting lasers. The results of experiments etching PBGs structures into the DBRs of GaAs-based proton-implanted and oxide confined VCSELs using focussed ion beam etching (FIBE) are presented. The results of etching a...

2 and 3D Finite Difference Time Domain (FDTD) simulations and measurements of a hexagonal lattice 2D photonic crystal with holes having taper angles in the region of 3 to 7 degrees are performed. The results show a smoothing of band edges and increased losses. Reasonably good agreement between measured and modelled results is obtained.

The FDTD method is used to design a InP photonic crystal (PC) waveguide filter operating at 1534 nm. The filter uses strong mode coupling effects which result in a small device area of 8 μm × 10 μm.

The 3D FDTD method is used to obtain loss versus hole depth in a 2D photonic crystal waveguide by simulating two different length guides. The transmission results are validated against published measured data. Good agreement between measured and simulated data is obtained for a mini-stop band of the PC WG. Intrinsic loss has been extracted from dif...

In this work a circularly symmetric structure is assumed. The field, thermal, standard carrier diffusion and photon rate equations are solved accordingly. The model used for the material gain is both carrier and temperature dependent, with the nonlinear dependency introduced by the use of a phenomenological gain suppression factor. The model is fle...

We demonstrate experimentally how an external mechanical stress applied to a VCSEL wafer results in an in-plane anisotropic strain, which dramatically alters the polarization behavior of our VCSELs. In the presence of in-plane strain, the VCSEL still emits linearly polarized light but its direction strongly depends on the magnitude and the orientat...

Vertical Cavity Surface Emitting Lasers (VCSELs) are a novel type of laser in which the lasing light is emitted from the surface of the device, perpendicular to the gain layer, rather than from the edge of the laser, parallel to the gain layer. These lasers show interesting behavior, particularly involving mode dynamics and polarization. They show...

Well resolved structure in the neutral donor bound exciton (D0X) recombination in InP, observed at high magnetic fields and low temperatures, is presented. This structure is explained using a model of a donor bound exciton in a cubic semiconductor in a magnetic field in which p-like zero-field excited states are forced to lower energy than the s-li...

A general group-theoretical method has been derived for the evaluation of Gamma * epsilon Jahn-Teller matrix elements for point- and double-point-group symmetries. In this notation Gamma corresponds to the irreducible representation labelling the degenerate electronic state and epsilon is the doubly degenerate representation labelling the vibration...

The operation of a new dual-purpose vertical-cavity surface-emitting laser (VCSEL), which functions either as a laser or as an avalanche detector, is presented. The original laser structure is modified by focused ion beam etching, enabling photodetection operation, with avalanche gain in excess of 10 available under reverse bias. Successful operati...

The decay of the zone-center longitudinal optical (LO) phonon in GaN into a transverse optical (TO) phonon and a longitudinal acoustic (LA) phonon is theoretically investigated. Its decay into two LA phonons is forbidden. A theoretical model is presented to study the effect of nonequilibrium LO and TO phonons on the electron energy relaxation rate....

A theoretical model is presented that is capable of simultaneously simulating the frequency response of the photon density, carrier density, electron temperature, hole temperature, populations of nonequilibrium longitudinal optical (LO) and transverse optical (TO) phonons at different wave vectors, and lattice temperature under the modulation of sm...

A novel dual-purpose vertical-cavity optoelectronic component, functioning either as a laser or as an avalanche photodetector, is employed in a link as a transceiver unit allowing “ping-pong” communications. Successful system performance is demonstrated at bit rates up to 1.244 Gbit/s

A new carrier barrier layer structure of II–VI compounds, which is ZnSeMgS strained-layer superlattice (SLS), was proposed and ZnSeMgS SLSs have been successfully grown by molecular beam epitaxy (MBE) for the first time. The ZnSeMgS SLSs showed photoluminescence (PL) due to the transition of electrons between the quantized levels. The current-volta...

Growth of ZnSe/MgS strained-layer superlattices (SLSs) has been carried out by molecular beam epitaxy. The crystal quality of SLSs degraded with MgS thickness of more than about 3 monolayers. Photoluminescence due to the transition between quantized levels was observed. Photoluminescence peak energies higher than 3.0 eV at 77 K were observed, which...

We calculate the finite-temperature inelastic scattering rate for hot electrons injected parallel to an n-doped GaAs/GaAlAs interface or quantum well for various doping densities n, temperatures T and injection energies. We use the Born approximation and a T-dependent two-pole Pade approximation to the full finite T, frequency omega and wavevector...

A study of the Fermi-energy-edge singularity in asymmetric modulation-doped quantum wells is reported. It is shown that high densities of free carriers in filled n=1 electron subbands have no significant influence on the edge singularity in partly occupied n=2 subbands, demonstrating the weakness of intersubband Coulomb-scattering processes. The en...

A simple excitonic theory is developed for the luminescence process in a 2d degenerate electron gas (DEG) both at zero and finite magnetic fields. The Schrödinger equation for the exciton is derived by treating the electron-hole interaction as a perturbation on the appropriate single particle eigenstates. The solutions give the excitonic enhancemen...

We have studied the low-temperature photoluminescence (PL) of n-type modulation doped quantum wells. The photocreated holes are localised and can recombine with any of the electrons. The PL lineshape is strongly skewed to higher energies, on account of the many-body Fermi energy edge singularity. This interpretation is supported by calculations of...

The observation of a Fermi energy edge singularity in the luminescence spectra of InGaAs/InP quantum wells is discussed. The importance of hole localization for the observation of the phenomenon is emphasized from the contrast between spectra obtained from samples with either strong or weak hole localization.

In the impurity system V2+:MgO, a d3 ion replaces a Mg2+ ion at an octahedral site. The resulting Zeeman spectra have been a puzzle for many years even with techniques employing high magnetic fields and low temperatures. In this paper, the system is treated as a Jahn-Teller 4T2g*( epsilon 1+ epsilon 2) system. In this treatment the triply degenerat...