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Electroabsorption modulators (EAM) based on quantum-confined Stark effect (QCSE) in multiple-quantum wells (MQW) have been demonstrated to provide high-speed, low drive voltage, and high extinction ratio. They are compact in size and can be monolithically integrated with source lasers. In order to achieve both high speed and low drive-voltage operation, travelling-wave (TW) electrode structures can...
A two-dimensional photonic crystal (2DPC) slab waveguide-based symmetric Mach-Zehnder type all-optical switch (PC-SMZ) is promising for a future ultra-fast photonic network system. An ultra-fast (~ps) and ultra-low energy (~100 fJ) switching has already been demonstrated as the 1st phase. The 2nd phase is to create a PC-SMZ-based ultra-fast photonic logical switch with a latch function for an ultra-fast...
GaInNAs/GaAs quantum wells are a relatively new material system for telecom/data com application. Generally it has been thought that the material offers an improved temperature performance and lattice matching to GaAs both significant advances. However studies of the material show that it has more parameters to control: in particular controlling the N distribution within the QW and the nature of the...
A polarization-insensitive optoelectronic integrated device composed of a tensile strained periodic coupled double quantum wells heterojunction phototransistor integrated over a compressive strained multi quantum well laser diode (MQW-LD) is proposed. This structure shows unresolved heavy hole and light hole transitions. So, the device operation mode (amplification or switching) is independent of...
A free space contra-propagation set-up is implemented and a dynamic pump-probe study of the eigenmodes of a SOA in the picosecond regime is undertaken. The time-resolved probe transmission of the TE and TM modes of the device is measured for the co and cross-polarised cases as a function of pump pulse energy. The relative contributions of interband and intraband processes to the gain compression are...
We describe the operating principle and performance of the 'turbo-switch', a new configuration of semiconductor optical amplifiers (SOAs) that gives an enhanced high-speed response for all-optical switching without compromising the optical signal-noise ratio. Error-free wavelength conversion is obtained at 170 Gb/s based on the use of an offset Mach-Zehnder interferometric filter incorporating a turbo-switch...
Monolithic semiconductor ring lasers (SRLs) have the potential to simultaneously address two important issues of modern optoelectronic systems for high-speed optical communications: integrability and ultrafast all-optical signal processing. SRLs do not require chip cleaving or refractive index grating for the definition of the laser cavity, and hence they allow to integrate several laser devices on...
The anticipated growth in demand for bandwidth leads to the development of all-optical signal processing techniques at ever increasing data rates. One possible candidate to achieve the required performance is the semiconductor optical amplifier (SOA). It has been demonstrated that ultra-fast gain processes are dominant for pulsewidths below 10 ps. In this paper we present experimental results on the...
Beam spoilers are an integral part of high-power laser diode design, being used to provide improved output beam quality by spatially filtering higher order field components from the backward travelling wave. They consist of deeply etched angled trenches and this inherent three-dimensional nature is one reason why, despite their practical importance, no systematic design of beam spoilers has been undertaken...
We will present a survey on our experimental and theoretical studies of polarization dynamics in vertical-cavity surface-emitting lasers (VCSELs) when subject to orthogonal optical injection, i.e. the injected field has a linear polarization (LP) orthogonal to that of the free-running VCSEL. The output characteristics of an oxide-confined AlGaAs-GaAs quantum well VCSEL are experimentally mapped as...
Influence of the gain saturation on the output performance of quantum-well heterostructures with modified distributed-feedback cavities is considered. Taking into account symmetrical boundary conditions, distribution of the electromagnetic field in the active region of the heterostructure laser diode with a phase-amplitude grating is determined. It is shown that both the output power of the source...
In the present paper, the modal optical fields within photonic-crystal vertical-cavity surface-emitting diode lasers (PC VCSELs) are calculated with the aid of the plane wave admittance method, a new advanced three-dimensional vectorial optical model. We determine the optimal diameter of PC holes within the PC VCSEL distributed-Bragg-reflector, which ensures the best field confinement within the VCSEL...
Recent progress achieved with integrated optical devices exploiting quasi-phasematched second order nonlinear interactions in periodically poled Ti:LiNbO3 waveguide structures is reported. Wavelength conversion, parametric amplification, multiplexing, and switching are demonstrated as examples of ultra-fast all-optical signal processing in the 1.5-mum wavelength range for transparent optical networks
The GaInNAs/GaAs semiconductor heterostructures have emerged as promising alternatives to InP-based compound semiconductors for the fabrication of 1.3-mum METRO and LAN telecommunications lasers. We shall review the recent advances made in the field of the GaInNAs technology. An emphasis is put on the development of low-threshold double-quantum-well (DQW) and triple-quantum-well (TQW) ridge waveguide...
We found a new class of heterostructures which have no discontinuities for one of the band edges and, therefore, called continuous-band heterostructures (CBHs). The promising properties of CBHs are discussed by consideration of their optical and electrical characteristics. CBH-based DBRs provide extremely low series resistance in comparison with conventional DBRs even at low level of doping that can...
The possibility of dynamically controlling the speed of light can be extremely useful in all the optical applications where a variable delay is needed, such as bit and frame synchronization and optical storage. To this aim, coupled resonator slow-wave structures (SWSs) represent a promising approach to slow down the propagation of optical signals with as large bandwidths as required by optical communication...
Ensemble Monte Carlo method is employed for the study of electron and phonon system in cubic GaN crystals subjected to femtosecond electric field pulses. Transient response is considered at the lattice temperatures of 15 and 300 K. THz electromagnetic wave emission by the transient electron drift response is found to be more effective at 300 K than at low temperatures. Contrary to it, low temperatures...
The feasibility of an Er3+-doped chalcogenide microstructured optical fiber amplifier has been demonstrated via accurate simulations performed by employing an appositely refined, home made, computer code. The optical and geometrical parameters measured on the first samples of microstructured optical fibers together with other physical constants taken by literature are considered in the simulation...
An important limiting factor for efficient white light emitting organic LEDs is the total internal reflection occurring at each interface. In a bottom emitting OLED light is trapped by reflection at the interface between the organic layers and glass substrate and at the interface between the glass substrate and air. We investigate the use of a grating at the glass substrate-air interface. In this...
All-optical signal processing is of high interest in view of potential applications in long-haul high-speed communication networks. One of the key techniques is based on active or passive nonlinear Bragg gratings with and without a tapering of the bandgap. Applications envisaged are all-optical switches, limiters, and isolators. For wavelength conversion, four-wave mixing (FWM) can be used, and resonant...
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