Browsing by Author "HEGARTY, JOHN"
Now showing items 23-41 of 41
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An experimental and theoretical analysis of jitter in self-pulsating lasers synchronized to periodic electrical signals
(1996)We investigate both experimentally and theoretically the behavior of pulse jitter in compact disk (CD) self-pulsating lasers that have been synchronized to an applied periodic electrical signal. Our investigations reveal ... -
Frequency locking and quasiperiodicity in a modulated external cavity injection laser
(American Institute of Physics, 1989)We report the observation of frequency locking and quasiperiodicity in a modulated external cavity injection laser. The order of appearance of the frequency-locked regions follows a Farey sequence as the modulation frequency ... -
Growth and characterization of an epitaxially grown ZnSSe/MnZnSSe distributed Bragg reflector
(1995)A Bragg reflector consisting of a 25-period MnZnSSe/ZnSSE Bragg stack is reported. The II?VI semiconductor structure was grown by molecular beam epitaxy on a GaAs ~100! epilayer. Structural characterization of the Bragg ... -
Hot-exciton relaxation in CdxZn1-xTe/ZnTe multiple quantum wells
(1991)We have observed the creation of hot excitons at high momentum in CdxZn1-xTe multiple quantum wells and subsequent relaxation by LO-phonon emission to give sharp luminescence lines superimposed on a broader background. The ... -
The influence of the unlocked characteristics of a self-pulsating laser diode on synchronization
(1993)All-optical synchronization and timing extraction based on self-pulsating twin section lasers has been demonstrated. We investigate the variation of the unlocked full-widthat- half-maximum of the fundamental of the RF ... -
Methane Sensing with a Novel Micromachined. Single-Frequency Fabry?Perot Laser Diode. Emitting at 1331 nm.
(1997)Spectroscopic-based gas sensing is demonstrated using micromachined single-frequency Fabry-Perot (FP) laser diodes emitting at 1.331 ?m with a side mode suppression ratio of greater than 24 dB over a significant emission ... -
Molecular beam epitaxy growth of MgZnSSe/ZnSSe Bragg mirrors controlled by in situ optical reflectometry.
(1995)In situ optical reflectometry at the wavelength of 488 nm was employed to control the growth of MgZnSSe/ZnSSe Bragg mirror stacks for the blue-green spectral region. 10- and 20-period layer structures of MgZnSSe/ZnSSe ... -
Observation of optical Stark effect in InGaAs/InP multiple quantum wells
(American Institute of Physcis, 1987)We report an experimental observation of a blue shift in the n=1 heavy-hole exciton line of In0.53Ga0.47As/InP multiple quantum wells resulting from a picosecond photoexcitation in the transparent spectral region. The ... -
Optical measurement of ion implantation damage depth in multiple-quantum-well mesa structures
(1991)We have determined the depth of ion implant damage in semiconductor materials by nonlinear optical measurements. The carrier lifetime in ion-implanted mesas was measured by the pump-probe technique, and the carrier ... -
Optical measurement of the ambipolar diffusion length in a ZnCdSe-ZnSe single quantum well
(American Institute of Physics, 1997)We describe a straightforward technique for the measurement of carrier diffusion in semiconductors. Using an optical microscope we can spatially image luminescence with a resolution of ~ 500 nm. We measured the ambipolar ... -
Optically pumped ZnCdSe-ZnSe quantum wells
(1996)We have measured the gain spectrum of an optically pumped 40A ZnCdSe-ZnSe multiple quantum well. Our calculation, which includes many body effects such as Coulomb enhancement and spectral broadening due to carrier ... -
Quasi-two-dimensional exciton in ZnSe/ZnMgSSe single quantum well
(American Physical Society, 1995)We have studied the quasi-two-dimensional exciton in ZnSe/ZnxMg1 ? xSySe1 ? y (x=0.85, y=0.21) single quantum wells (SQWs) by photoluminescence and photoluminescence excitation spectroscopy. Self-consistent calculations ... -
Ribavirin Enhances IFN-α Signalling and MxA Expression: A Novel Immune Modulation Mechanism during Treatment of HCV
(2011)The nucleoside analogue Ribavirin significantly increases patient response to IFN-? treatment of HCV, by directly inhibiting viral replication. Recent studies indicate that Ribavirin also regulates immunity and we propose ... -
Room-temperature exciton luminescence in II-VI quantum wells
(1991)We observe free excitons in absorption and emission at room temperature in Cd0,2sZne.7sTe/ ZnTe multiple quantum wells. A large overlap between luminescence and absorption peaks observed at 10 K is maintained up to room ... -
Sampled grating DBR laser as a spectroscopic source in multigas detection at 1.52-1.57um
(2001)The first application is reported of multigas sensing using a widely tuneable sampled grating DBR laser with a tuning range 1520⩽?⩽1570 nm. The laser diode consists of four independently biased sections, two sampled ... -
Small-signal analysis of 1.3/spl mu/m microcavity light-emitting diodes
(1999)THE MODULATION SPEED OF 1.3-MU M MICROCAVITY LIGHT-EMITTING DIODES (MCLED'S) HAS BEEN MEASURED USING A SMALL-SIGNAL MODULATION ANALYSIS, A SPEED OF 260 MHZ USING A 25-MU M DIAMETER SAMPLE AT CURRENT DENSITY OF 10 KA/CM(2) ... -
Strain effect on the optical nonlinearity in an InGaAs/GaAs asymmetric Fabry-Perot modulator.
(American Physical Society, 1993)The effect of strain on the optical nonlinearities and operation of an all-optical asymmetric Fabry-Perot italon is investigated. A high reflectivity modulation of 60% is reported with a contrast ratio of 12.2:1 and ... -
A theoretical analysis of optical clock extraction using a self pulsating laser diode.
(1999)The potential for using inexpensive compact disc laser diodes as optical clock extraction elements in transparent networks has led to an increase in research into the dynamics of self-pulsating laser diodes. We use a ...
