Browsing by Author "HEGARTY, JOHN"
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All-optical synchronization and frequency division of mode-locked pulses
HEGARTY, JOHN (1992)We report all-optical synchronization and frequency division of mode-locked input signals, using a selfpulsating laser diode. The performance of mode-locked and sinusoidal input signals are compared. Synchronization ... -
All-optical synchronization and multiplication of the frequency of mode-locked signals
HEGARTY, JOHN (IEEE, 1993)We report all-optical synchronized multiplication by rational fractions of the modulation frequency of optical signals in self-pulsing two-section semiconductor laser diodes. The effect is based on the overlap of harmonics ... -
All-optical synchronization of self-pulsating laser diodes
HEGARTY, JOHN (1996)We examine the behavior of self-pulsating laser diodes when injected with periodic optical signals. We experimentally and theoretically investigate the phase difference between the injected optical signal and the ... -
Asymmetric Fabry-Perot device arrays with low insertion loss and high uniformity
HEGARTY, JOHN (IEEE, 1992)We report on arrays of normally ON asymmetric Fabry-Perot modulator (AFPM) devices which exhibit a high degree of uniformity between devices, with a thickness variation across an array of 0.07%. The devices in one array ... -
Bistable self-electro-optic operation of strained In0.1Ga0.9As/GaAs asymmetric Fabry Perot modulators
HEGARTY, JOHN (1991)We report bistable operation of a strained-layer InGaAs/GaAs asymmetric Fabry-Perot optical modulator configured as a self-electro-optic effect device (SEED) operating in reflection mode. Bistable loops are observed from ... -
Calculated Threshold Currents of Nitride- and. Phosphide-Based Quantum-Well Lasers
HEGARTY, JOHN (1996)No abstract available. -
Calculation of gain?current characteristics in ZnCdSe?ZnSe quantum well structures including many body effects.
DONEGAN, JOHN FRANCIS; HEGARTY, JOHN (American Institute of Physics, 1996)The gain-spontaneous recombination characteristics have been calculated for a 40 ? Zn0.8Cd0.2Se-ZnSe quantum well including many body effects. We examine the effect of the inclusion of the Coulomb enhancement on the gain ... -
Carrier lifetimes in strained InGaAs/(Al)GaAs multiple quantum wells
HEGARTY, JOHN (1993)The etfect of strain, strain relief, and barrier design on the carrier lifetime in InGaAs/(Al)GaAs multiple-quantum-well samples is investigated. Carriers lifetimes are measured in samples with varying amount of strain, ... -
Carrier-density dependence of the photoluminescence lifetimes in ZnCdSe/ZnSSe quantum wells at room temperature
DONEGAN, JOHN; HEGARTY, JOHN (1999)Photoluminescence lifetimes have been measured at room temperature as a function of carrier density in ZnCdSe/ZnSSe quantum wells. We show that, at low carrier density (53109?5 31010 cm22), nonradiative recombination ... -
Carrier-density dependence of the photoluminescence lifetimes in ZnCdSe/ZnSSe quantum wells at room temperature
HEGARTY, JOHN (American Institute of Physics, 1999)Photoluminescence lifetimes have been measured at room temperature as a function of carrier density in ZnCdSe/ZnSSe quantum wells. We show that, at low carrier density (5 ? 109?5 ? 1010 cm ? 2), nonradiative recombination ... -
Demonstration of high-brightness-mode propagation in a compound waveguide structure
HEGARTY, JOHN (American Institute of Physics, 1999)We demonstrate the existence of an unusual and useful high-brightness guided mode of a multimode AlGaAs/GaAs heterostructure compound slab waveguide. This mode has a narrow near-field single lobe confined to the low-index ... -
Design and Construction of an Optoelectronic. Crossbar Switch Containing a Terabit per. Second Free-Space Optical Interconnect
HEGARTY, JOHN (1999)THE COMPLETED DETAILED DESIGN AND INITIAL PHASES OF CONSTRUCTION OF AN OPTOELECTRONIC CROSSBAR DEMONSTRATOR ARE PRESENTED. THE EXPERIMENTAL SYSTEM USES HYBRID VERY LARGE SCALE INTEGRATED OPTOELECTRONICS TECHNOLOGY WHEREBY ... -
Effect of Coulomb enhancement on optical gain in (Zn,Cd)Se/ZnSe multiple quantum wells
DONEGAN, JOHN FRANCIS; HEGARTY, JOHN (American Physical Society, 1997)The optical-gain spectra of a 40-? (Zn,Cd)Se/ZnSe multiple quantum well has been measured at various temperatures using a variable-stripe method. By comparison with a gain calculation including many-body effects, we have ... -
Effect of dispersion on the reflectivity of an asymmetric Fabry?Perot etalon
HEGARTY, JOHN (American Institute of Physics, 1995)We have shown that the spectral properties of an asymmetric Fabry?Perot etalon, with a multiple quantum well cavity, are very sensitive to dispersion in the refractive index. We also show that this effect can be used to ... -
Effect of temperature on self-pulsation in narrow stripe, gain-guided, compact disk laser diodes
HEGARTY, JOHN (IEEE, 1998)There is an ongoing strong interest in the development of red self-pulsating lasers for data storage compact disk (CD) applications.? Of particular importance in this mass-market application is that the laser diode ... -
Electro-optic modulation using asymmetric Fabry-Perot laser diode amplifiers.
HEGARTY, JOHN (1994)We report the use of laser diode amplifiers, whose facets have unequal mirror reflectivities, as asymmetric Fabry-Perot modulators. Due to the presence of optical gain in these devices we observe modulation of reflected ... -
Engineering the exciton linewidth in II-VI quantum well structures
DONEGAN, JOHN FRANCIS; HEGARTY, JOHN (SPIE, 1994)The excitonic transition in Il-VI quantum well materials has recently been used as the basis for optical modulators and also as the lasing transition at low temperatures. The central aspect in the use of the exciton ... -
Excitation-induced coherence in a semiconductor microcavity
HEGARTY, JOHN (American Physical Society, 2002)We measure the dephasing times of high finesse semiconductor microcavities in the strong coupling regime using degenerate four-wave mixing. We find that under certain excitation conditions (near-normal incidence) the ... -
Exciton line broadening in CdxZn1?xTe/ZnTe multiple quantum wells
HEGARTY, JOHN (American Institute of Physics, 1988)We have investigated Cdx Zn1?xTe/ZnTe multiple quantum wells using absorption techniques. We have observed sharp excitonic features at low temperatures which strongly broaden at room temperature. The strength of the ... -
An experimental and theoretical analysis of jitter in self-pulsating lasers synchronized to periodic electrical signals
HEGARTY, JOHN (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 ...