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A traveling-wave model is used for describing the changes in the directionality of the emission of semiconductor ring lasers and its different behavior when current is increased or decreased. The modulation of the cavity losses imposed by the light extraction sections together with the thermal shift of the gain spectrum and spatial hole burning in the carrier density has played a vital role in the directionality of the emission and its changes with operation current.

The design and measurements of a novel InP-based hybrid mode-locked laser diode (MLLD) structure with an ultrafast monolithically integrated, reverse-biased, uni-traveling-carrier (UTC) absorber are presented. The MLLD has shown clean sub-ps pulses of 900 fs at 42-GHz repetition rate and the potential in an optimized device to reach values around 600 fs.

The degradation of InGaN-based laser diodes for Blu-ray technology is described. The observed degradation of the laser is attributed to an electrothermally activated process that induces an increase in the nonradiative recombination rate with subsequent decrease in the optical efficiency of the active layer.

The design and properties of an evanescent coupling method developed by using a semiconductor antiresonant reflecting optical waveguide and a side-polished fiber is discussed. The newly developed side-coupled fiber semiconductor laser could be applied to design and fabricate hybrid fiber-semiconductor devices.

The design of a theoretical model of a wave-length-locked Fabry-Perot laser diode (F-P LD) to a sliced spectrum of externally injected amplified spontaneous emission (ASE) from wave equation is reported. The model could be applied to study the noise characteristics of a wavelength-locked F-P LD with respect to the various parameters, including the injected ASE power, the bias current of F-P LD, and the wavelength detuning.

The use of synthetic diamond for intracavity thermal management in compact solid-state lasers is examined. Findings reveal that the synthetic diamond samples possess significantly lower birefringence as compared to natural single-crystal diamond.

The fabrication of high-reliability and high-speed 1.3 [mu]m complex-coupled distributed feedback (CC-DFB) buried heterostructure (BH) laser diodes (LDs) with Fe-doped InGaAsP/InP hybrid grating layers is discussed. High-speed characteristic up to 11.8 GHz at room temperature is observed.

An all-fiber laser tunable by a filter composed of two Sagnac interferometers in series is discussed. Findings reveal a bandwidth reduction of the transmission peak, a single-line laser emission and a tuning sensitivity of approximately -0.8nm/degree Celsius.

The switching, locking and stability properties of a bistable semiconductor ring laser (SRL) are examined subject to an external optical injection. The smallest of the minimum switching settling time (MSST) for both direction of SRL at certain detuning frequencies is found in the negative detuning frequency side.

The effectiveness of multiple layers of In(Ga,Al)As/GaAs self-organized quantum dots (QDs) as a dislocation filter in the growth of GaAs-based InGaAs QD lasers on silicon substrates is examined. Findings reveal that the most effective dislocation filter comprises of ten layers of InAs QDs of approximate size of 20-30 nm.

The analysis of the degradation behavior of 2-[mu]m wavelength distributed feedback lasers with a p- and n-type InP buried heterostructure during constant power aging is discussed. Results suggest the governance of degradation mechanism by diffused defects with parallel direction in the crystal plane.

The various recent developments in the GaAs-based 1.55-[mu]m dilute-nitride lasers grown by molecular beam epitaxy (MBE) are reported. These nitrides are replacing other materials because of their higher gain and greater range of achievable band offsets.

The simulation model based on digital filter method for Vertical External Cavity Semiconductor Lasers (VECSEL) devices on the basis of the components and numerical implementation is described.

The integrated device of electrical and optical coupling in an electroabsorption (EA) modulator with a distributed feedback (DFB) laser is investigated by measuring the scattering parameters. When the current is applied to the laser section it shows the electrical coupling between the integrated devices.

The mode frequencies, field distributions and Q-factors for all modes confined in rectangular resonators are studied applying finite-difference time-domain (FDTD) method and Pade approximation method. The outcomes demonstrate that the Q-factors of the high Q-factor combined modes are over one order larger compared to the original modes and the common conditions needed to achieve high Q-modes are discussed.

An Ac admittance measurement along with I-V plot is applied to measure accurate forward electral characteristics of multi-quantum-well (MQW) lasers. For the first time, a sudden change of behavior is noticed and characterized, at the commencement of lasing.

The contrast between the outcomes of the optical scalar and vectorial optical techniques applying the scalar effective frequency method and the vectorial method of lines, respectively, applied for simulating an operation of the standard 1.3 -mum GaAs-based oxide-confined GaInAsN double quantum-well vertical-cavity surface-emitting diode lasers (VCSELs) using it as their typical examples are described.

An analysis of the effect of p-doping on the threshold current and its temperature dependence is presented. Results reveal that Auger recombination in quantum dashes is the major contributor to the threshold current at room temperature and helps in establishing a threshold current at room temperature.

A room temperature (RT) negative [T.sub 0] that is achieved in p-type modulation doped QD lasers are discussed. It is seen that the p-type modulation doped laser exhibits a positive [T.sub.0], while a negative [T.sub.0] occurs for a reference undoped laser.

Mechanism causing sudden failure of InGaAs/GaAs strained-layer quantum-well lasers (LD) is analyzed by monitoring an optical beam-induced current (OBIC). The OBIC technique being nondestructive, highly sensitive and having a high-spatial resolution is extensively used in degradation analyses of optoelectronic devices.

High-density plasma etching of InP-based compound semiconductor lasers with Cl2-N2-based gas mixtures using the inductively coupled plasma (ICP) etching system and the demonstration of microring layers coupled to nanoscale waveguides are described. A submilliampere threshold current is obtained at room temperature for the waveguide-coupled microning lasers with a diameter of 10 micrometer.

The path that led to the measurement of positive gain on the 1315-nm transition of atomic iodine is reported where the O2(a(super 1)delta) was produced in a flowing electric discharge. Atomic oxygen was found to play both positive and deleterious roles in this system, and as such the excess atomic oxygen was scavenged by NO2 to minimize the deleterious effects.

The injection of two chaotic modes of a multimode semiconductor laser with optical feedback into two single-mode stand-alone semiconductor lasers leads to chaotic synchronization between the respective intensities is shown numerically. Further, the effect of parameter mismatch between the transmitter and receiver lasers is examined.

The influence of parameter and receiver systems on the bit error rate of an optical chaos communicating scheme is investigated. Intensity hyperchaos is generated in the system by semiconductor lasers with electrooptical feedback.

The use of crystalline heatspreaders to improve thermal management in optically pumped vertical-external-cavity surface-emitting lasers is studied through finite-element analysis. The required properties of a heatspreader are examined and the effect on heat flow is discussed, as are thermal lensing effects.

The potential of 1.3-micrometer AlGaInAs multiple quantum-well laser diodes for uncooled operation in high-speed optical communication systems is experimentally evaluated by characterizing the temperature dependence of key parameters such as the threshold current, transparency current density, optical gain and carrier lifetime.

An experimental comparative study of the gain, index variation, and linewidth enhancement factor in 980-nm quantum-well (QW) and quantum-dot (QD) lasers structures, designed for high power applications, is presented. The gain spectra of the QW lasers at high injection level revealed three different transition energies, with a low linewidth enhancement factor for E2HH2 transitions.

A conceptual design for a compact megawatt class free-electron laser (FEL) operating at 1 (mu)m is presented. In the design with frequency detuning and uniform wiggler, the efficiency is ~1.8 percent and the electron-pulse slippage is substantially reduced in a high-gain amplifier.

The passive modal absorption, modal gain, and spontaneous emission spectra of a quantum-dot system is measured where the inhomogeneous broadening is sufficiently small so that the ground and excited state transitions can be spectrally resolved. The measured population inversion factor spectrum shows that the carrier distribution cannot be described only by a single global Fermi distribution and that the system is not in overall equilibrium.

A theoretical and experimental study of optical gain and the linewidth enhancement factor (LEF) of type-I quantum-cascade (QC) laser is reported. QC lasers have a symmetrical gain spectrum because the optical transition occurs between conduction subbands.

A single-pass method was employed to measure the gain and absorption in optically pumped midinfrared type-II semiconductor lasers. The gain measurements confirm that the differential gain of these structures drops off rapidly with increasing temperature.

A detailed theoretical study of a vertical cavity surface-emitting laser (VCSEL) with two optically coupled active cavities is presented. An intuitive model of rate equations is used for photons and for carriers written for the two cavities under steady-state conditions.