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Quantum Electronics, IEEE Journal of

Issue 1 • Date Jan. 2000

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Displaying Results 1 - 17 of 17
  • Guest editorial

    Page(s): 1
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    Freely Available from IEEE
  • Lasing and stimulated emission in /spl pi/-conjugated polymers

    Page(s): 2 - 11
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    Recent studies of lasing and stimulated emission in luminescent /spl pi/-conjugated polymers performed by our group are presented. Optical properties of cylindrical high-Q polymer microcavities are discussed. The emission spectra of plastic microring and microdisk lasers are measured and analyzed. Light-emitting polymer microdiodes are demonstrated as possible candidates for electrically driven plastic lasers. In addition, two unusual regimes of stimulated emission characterized by narrow laser-like spectral lines are demonstrated in thin waveguiding polymer films. These regimes may be associated with random optical feedback introduced by light scattering inside the polymer films and amplified Raman scattering, respectively. View full abstract»

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  • High T/sub g/ hole transport polymers for the fabrication of bright and efficient organic light-emitting devices with an air-stable cathode

    Page(s): 12 - 17
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    An organic electroluminescent device with a luminous efficiency of 20 Im/W, at 14 cd/m/sup 2/, and an external quantum efficiency of 4.6% has been fabricated using a high T/sub g/ hole transport polymer, a small molecule emission layer, and a LiF/Al cathode. The device quantum efficiency can be increased by tuning the ionization potential of the hole-transport moieties. When tested under pulsed voltage mode, in air at room temperature, and without any encapsulation, the device showed a high peak brightness of 4.4/spl times/10/sup 6/ cd/m/sup 2/ at 100 A/cm/sup 2/ and an efficiency of 4.4 cd/A. View full abstract»

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  • Structures for organic diode lasers and optical properties of organic semiconductors under intense optical and electrical excitations

    Page(s): 18 - 26
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    The challenges to realizing diode lasers based on thin films of organic semiconductors are primarily related to low charge carrier mobility in these materials. This not only limits the thickness of organic films to /spl les/100 nm in electrically pumped devices, but it also leads to changes in the optical properties of organic films induced by the large number of carriers trapped in the materials subjected to an intense electrical excitation. We describe organic waveguide laser structures composed of thin organic films and transparent indium-tin-oxide electrodes. These waveguides allow for efficient injection of an electrical current into the organic layers and provide for low optical losses required in a laser. The changes in the optical properties of organic thin films induced by electrical excitation are studied using electroluminescence and pump and probe spectroscopy. Induced transparency and absorption observed in the organic materials may be related to triplet excitons or trapped charge carriers. Pump-induced absorption is also observed in organic films under quasi-CW optical excitation. These effects must be taken into account both in the design of organic diode laser structures and in the selection of charge transporting materials. View full abstract»

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  • Open-loop chaotic synchronization of injection-locked semiconductor lasers with gigahertz range modulation

    Page(s): 27 - 34
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    Unidirectional chaotic synchronization between two remote injection-locked semiconductor lasers to achieve chaotic communications is investigated numerically. Different from the direct chaotic masking methods, the chaotic carrier wave is generated from different chaotic states in transience instead of a fixed chaotic state in static to prevent it from being reproduced through a reconstructed embedding phase space. The testing digital and sinusoidal message signals in the gigahertz range can be easily recovered without the use of any electronic or optical filter to filter out the synchronization error. The robustness of synchronization is examined by using the intrinsic white noise of the transmitter and the receiver as the perturbation. The effects of parameter mismatches on the quality and robustness of synchronization are analyzed in detail. The results show that different internal parameters have very different tolerances for parameter mismatch. A short discussion on the phase sensitivity of synchronization is also given. View full abstract»

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  • Message encoding and decoding using chaotic external-cavity diode lasers

    Page(s): 35 - 39
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    Synchronization of chaotic external-cavity diode lasers has been studied in a master-slave configuration. A message is encoded into the chaotic master laser by amplitude modulation and transmitted to the slave laser. A scheme for decoding the message at the slave is demonstrated. View full abstract»

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  • High-performance chemical oxygen-iodine laser using nitrogen diluent for commercial applications

    Page(s): 40 - 51
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    A chemical oxygen-iodine laser (COIL), the VertiCOIL device, was transferred from the Air Force Research Laboratory (AFRL) to the University of Illinois at Urbana-Champaign (UIUC) and made operational. The performance of the high-power VertiCOIL laser was measured with nitrogen diluent, New nozzle designs were investigated and implemented to optimize nitrogen performance, Nitrogen diluent chemical efficiencies of 23% were achieved; these are the highest reported chemical efficiencies with room-temperature nitrogen diluent. A long duration, high chemical efficiency test was demonstrated with nitrogen diluent; a chemical efficiency of 18.545 at 30 mmol/s of chlorine was maintained for 35 min. The highest performance was obtained with new iodine injector blocks and a larger throat height. The new iodine injector blocks moved the injectors closer to the throat by 0.7 cm and the throat height was increased from 0.897 to 1.151 cm (0.353 to 0.453 in). The performance enhancements were in qualitative agreement with the system design predictions of the Blaze II chemical laser model. Three-dimensional computational fluid dynamics calculations using the general aerodynamic simulation program code confirmed the principle design change of moving the iodine injectors closer to throat. View full abstract»

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  • Analysis and optimum design of distributed feedback lasers using coupled-power theory

    Page(s): 52 - 58
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    Based on coupled-power theory, the analysis and optimum design of distributed feedback (DFB) lasers are discussed. It is shown that the lowest threshold and the elimination of spatial hole burning in antireflection-coated index-coupled/gain-coupled/complex-coupled DFB lasers can be achieved by properly choosing DFB laser parameters such as the phase shift value, variations of the grating along the cavity, etc. It is also shown that coupled-power theory is simple and provides an easy approach to analytical understanding of the physical mechanisms crucial for the optimum design of DFB lasers. View full abstract»

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  • Modeling of photoinduced charge separation in germanosilicate optical fibers during UV-excited poling

    Page(s): 59 - 69
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    We report numerical solutions of a proposed model for charge separation and trapping during poling of germanosilicate fiber in the presence of ultraviolet (UV) light. The model was solved quantitatively in the steady state to determine the space charge field distribution after UV-excited poling of a germanosilicate optical fiber with internal electrodes. The resulting internal electric field was found to be up to an order of magnitude higher than the initial poling field, sufficient to produce an effective second-order nonlinearity consistent with experimental observations by the internal field acting on the inherent third-order nonlinearity. The effects of core-cathode spacing, nonuniform defect distributions, and photo-electron recombination rate on the induced /spl chi//sub eff//sup (2)/ were also investigated. It is shown that a small core-cathode spacing is advantageous. Our UV-poled field solutions may also apply to thermal poling, provided we swap the anode and cathode designations. The results suggest that it is optimal to have the core located in the depletion region regardless of poling method. View full abstract»

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  • Noise characterization of a regeneratively mode-locked fiber ring laser

    Page(s): 70 - 78
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    A regeneratively mode-locked fiber ring laser (RML-FRL) and an active harmonically mode-locked fiber ring laser (ML-FRL) have been characterized for both amplitude and phase noise by investigating the detected RF spectra of the optical pulse trains. Quantification of noise in the optical pulses reveals that the stability of the RML-FRL in terms of noise performance is superior to its ML-FRL counterpart. The optical pulse noise was measured over a frequency band of 100 Hz to 100 kHz and it was found that the pulse amplitude noise reduced from 0.6% in the ML-FRL to 0.3% in the RML-PRL. The total rms noise in the detected optical pulses from the RML-FRL improved by more than 30% compared to that measured for the ML-FRL, with a phase noise improvement of 15 dB at 100 kHz offset frequency from the carrier. An rms timing jitter of 0.38 ps was estimated in the optical pulse train from the ML-FRL, which reduced to 0.26 ps in the RML-FRL. In addition, complete elimination of the relaxation oscillations noise spikes in the detected RF spectrum of the optical pulses from the RML-FRL has been observed. View full abstract»

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  • Multiloop optoelectronic oscillator

    Page(s): 79 - 84
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    We describe and demonstrate a multiloop technique for single-mode selection in an optoelectronic oscillator (OEO). We present experimental results of a dual loop OEO, free running at 10 GHz, that has the lowest phase noise (-140 dBc/Hz at 10 kHz from carrier) of all free-running room-temperature oscillators to date. Finally, we demonstrate the first fiber-optic implementation of the carrier suppression technique to further reduce the close-to-carrier phase noise of the oscillator by at least 20 dB. View full abstract»

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  • A novel method for laser-induced periodic domain reversal in LiNbO/sub 3/ [nonlinear optical waveguide]

    Page(s): 85 - 88
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    An intense laser light in conjunction with a strong localized field is used to reverse the polarity of the ferroelectric domain at the location of a laser beam. The focus beam from an argon laser raises the temperature of a moving z-cut LiNbO/sub 3/ plate close to the Curie point when a bipolar square wave electric field is applied. This technique has been used to construct a nonlinear periodic optical waveguide structure. This waveguide can be used for quasi-phase-matched second-harmonic generation. The applications of such waveguides are well documented in the literature. View full abstract»

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  • Self-switching with a nonlinear birefringent loop mirror

    Page(s): 89 - 93
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    We investigate switching characteristics of the nonlinear birefringent loop mirror which consists of a symmetric directional coupler, a birefringent fiber, and a symmetry-breaking element that converts linearly polarized light to circularly polarized light, and vice versa. The condition for total reflection in the linear regime is obtained using the Jones matrix formalism, The switching curves have been obtained through numerical computations both in the nondispersive pulse regime and in the soliton-like pulse regime. Parameter values suitable for practical applications of our device as an intensity filter are obtained. View full abstract»

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  • Absorptive switching and spectral characteristics of the side-injection light-controlled bistable laser diode

    Page(s): 94 - 99
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    Experimental results characterizing the operation of the side-injection light-controlled bistable laser diode (SILC-BLD) have been accurately modeled using simple gain expressions and rate equations. Light output versus gain section drive current has been calculated and agrees well with experiment. Further, voltage shifts (due to carrier redistribution between the gain and absorber regions) measured at switch on and off have also been modeled successfully for what is believed to be the first time in a quantum-well laser to the authors' knowledge, and agree well with experiment. Spectrally, subthreshold power-averaged wavelength versus gain section drive current measurements show a parabolic form (caused by the interplay between band filling, energy gap shrinkage, and the increase in stimulated emission). This has been successfully modeled using quantum-well gain and the associated spontaneous emission spectra, and should have wide applicability to all Fabry-Perot semiconductor lasers. View full abstract»

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  • Ultrafast all-optical switching with an asymmetric Fabry-Perot device using low-temperature-grown GaAs: material and device issues

    Page(s): 100 - 111
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    For future telecommunications systems to take full advantage of the optical fiber bandwidth, it will be necessary to have components responding at picosecond speeds. The only way currently known to achieve these speeds is using all-optical switching. By using low-temperature-grown GaAs (LT-GaAs) in a compact asymmetric Fabry-Perot device, we have achieved ultrafast all-optical switching with large bandwidth, high contrast ratio, low insertion loss, and low switching energy. In this paper, we discuss the dependence of the switch performance on the mirror bandwidth and reflectivity, and the LT-GaAs layer thickness and growth conditions. We develop guidelines for the optimization of the device design to maximize the bandwidth and contrast ratio. View full abstract»

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  • Modulation response of multiple transverse modes in vertical-cavity surface-emitting lasers

    Page(s): 112 - 117
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    The small-signal modulation response of multiple transverse modes in a vertical-cavity surface-emitting laser was studied numerically. The overlap between the modal distribution of the field and the carrier distribution in the active region is fundamental to determining the modulation response, According to the injection current level, the modulation response curve in several configurations and parameters used can display peaks and notches that may impair the frequency response of the device. These features reflect the competition of carrier by the operating modes in a way that can be described as interference. Therefore, the total modulation response curve cannot be evaluated from the modulation response of the individual modes. View full abstract»

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  • Design and ASE characteristics of 1550-nm polarization-insensitive semiconductor optical amplifiers containing tensile and compressive wells

    Page(s): 118 - 122
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    The polarization dependence of 1550-nm semiconductor optical amplifiers (SOA's) containing tensile and compressive wells has been investigated both theoretically and experimentally. Our model to predict the polarization-resolved (TE and TM) gain spectra of these structures has been confirmed by amplified spontaneous emission measurements. It is found that there can be appreciable carrier redistribution between the two types of wells when the tensile layers have the large thickness (greater than 100 /spl Aring/) needed for gain at wavelengths around 1550 nm. This carrier redistribution can significantly modify the ratio of the gains for different polarizations, in particular, decreasing the TM gain with respect to the TE gain, and, hence, is an important design consideration. We use our model and experimental data to explore design criteria for 1550-nm polarization-independent SOA's. View full abstract»

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Aims & Scope

The IEEE Journal of Quantum Electronics is dedicated to the publication of manuscripts reporting novel experimental or theoretical results in the broad field of the science and technology of quantum electronics..

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Aaron R. Hawkins
Brigham Young University