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  • 1
    Electronic Resource
    Electronic Resource
    Transient electroluminescence of polymer light emitting diodes using electrical pulses (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5116-5130 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Detailed experimental and theoretical analysis of the pulsed excitation of polymer light emitting diodes is presented. We find a set of universal transient features for a variety of device configurations (different polymers/cathodes) which can be reproduced using our phenomenological numerical model. We find that the temporal evolution of the electroluminescence in response to a step voltage pulse is characterized by: (i) a delay followed by; (ii) a fast initial rise at turn-on followed by; (iii) a slow rise (slower by at least one order of magnitude). The large mobility mismatch between holes and electrons in conjugated polymers allows us to separately time resolve the motion of holes and electrons. We suggest a method for extracting mobility values that takes into account the possible field-induced broadening of carrier fronts, and which is found to be compatible with mobilities determined from constant wave measurements. By using appropriate device configurations it is possible to determine the mobilities of both holes and electrons from a single device. Mobilities for holes and electrons are extracted for a poly(p-phenylenevinylene) copolymer and poly(di-octyl fluorene). © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371488
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  • 2
    Electronic Resource
    Electronic Resource
    Role of optical properties of metallic mirrors in microcavity structures (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2825-2829 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In thin metal films the phase change on reflection of incident light is dependent on the wavelength, the angle of incidence, the type of metal, and the metal thickness. These properties have been exploited to improve the performance of planar metal mirror microcavities. We model substantial alteration of peak emission wavelength and linewidth with mirror thickness. This allows the tuning of the cavity resonance wavelength by variation of metal mirror thickness. The dependence of the phase change on wavelength and angle of incidence can also be used to suppress the angular dependence of the cavity resonance wavelength. These effects are observed in silver-mirrored cavities containing the polymers poly(p-phenylene vinylene), (PPV), and a cyano-substituted derivative of PPV, MEH-CN-PPV. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363940
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  • 3
    Electronic Resource
    Electronic Resource
    Current heating in polymer light emitting diodes (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 732-734 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an investigation of current-induced heating in polymer light emitting diodes. Using short electrical pulse measurements, we were able to quantify the temperature rise in the active region. We consider that heating effects play a major role in limiting the maximum efficiency of devices and in initiating degradation mechanisms. Heating and heat sinking are also discussed in the context of electrically pumped polymer lasers. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121983
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  • 4
    Electronic Resource
    Electronic Resource
    Gain dynamics in quantum well lasers and optical amplifiers: An experimental comparison (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2050-2052 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe an experimental comparison of gain dynamics in quantum well lasers and optical amplifiers. We demonstrate an approximately 30% increase in the time constant describing the gain recovery on the ∼1 ps time scale in a laser above threshold. The increase is due to the high rate of stimulated emission which modifies the relative significance of the various mechanisms contributing to the gain recovery. We suggest an explanation based on the coupling of two processes: Carrier capture and carrier cooling. We conclude that laser gain dynamics contain details that cannot be revealed in experiments on optical amplifiers due to the vast differences in operating conditions between a laser and an optical amplifier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111733
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  • 5
    Electronic Resource
    Electronic Resource
    Nonequilibrium effects in quantum well lasers (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2383-2385 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a simple technique of measuring the effect of the finite capture time of carriers in quantum well lasers on the homogeneity of the gain. The effect is measured using an extended cavity laser configuration in which we control the feedback level and compare the two extreme cases of a laser and a nonlasing amplifying gain medium. Broadband measurements of the spontaneous emission at energies near the top of the well and above the barriers show an inhomogeneous gain saturation which depends on the photon density inside the cavity. The results agree with a simple model for carrier injection in quantum well lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108197
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  • 6
    Electronic Resource
    Electronic Resource
    Coupling between barrier and quantum well energy states in a multiple quantum well optical amplifier (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 665-667 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the interaction between carriers in three-dimensional barrier and confinement regions and two-dimensional quantum well regions of a 1.5 μm multiple quantum well optical amplifier. We present a model and measurements of the spontaneous emission and gain spectra dependence on an external optical pump signal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106585
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  • 7
    Electronic Resource
    Electronic Resource
    Measurements of the barrier-well injection bottleneck in a multiple quantum well optical amplifier (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1788-1790 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe broadband static pump probe measurements of the barrier-well injection bottleneck caused by a complicated interaction between three- and two-dimensional carriers in a 1.5-μm multiple quantum well optical amplifier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107165
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  • 8
    Electronic Resource
    Electronic Resource
    Short cavity distributed Bragg reflection lasers with a narrow band Bragg mirror: Dynamic characteristics (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 3048-3050 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamical characteristics of distributed Bragg reflection lasers with a Bragg reflection bandwidth narrower than the cavity mode spacing are reported. The operation of this Bragg reflector as an amplitude modulator (unlike the usual frequency modulator) is demonstrated in the small and large signal modulation regimes. In the conventional mode of gain modulation, this narrow Bragg reflector exhibits detuned loading effects. The laser is capable of efficient digital modulation as well as Q-switching, both with a very small drive current. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112990
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  • 9
    Electronic Resource
    Electronic Resource
    Broadband femtosecond pump-probe setup operating at 1300 and 1550 nm (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1899-1901 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a broadband, tunable femtosecond pump-probe measurement setup operating in the 1300 and 1550 nm wavelength range. We demonstrate measurements of carrier dynamics in the barrier states of a multiple quantum well optical amplifier. The amplifier is excited (pumped) in the gain region near 1510 nm and probed, with femtosecond time resolution, in the barrier region, at 1300 nm, yielding dynamical details which cannot be observed with conventional, single- wavelength pump-probe techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111762
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  • 10
    Electronic Resource
    Electronic Resource
    Distributed nature of quantum-well lasers (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 10-12 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, we show that a quantum-well laser should be modeled as a distributed, rather than a lumped, device. Using a detailed model of current injection which analyzes electron and hole distribution in space as well as in energy, we demonstrate that the static and dynamic laser responses are not uniform along the growth axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108827
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