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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of stepped-well and square-well multiple-quantum-well optical modulators (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1411-1414 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The responsivity and transmission performance of 60-period p-i-n multiple-quantum-well (MQW) optical modulators having single or double steps in the quantum well (QW) has been experimentally compared to a square-QW control sample. It has been confirmed that significantly increased shift of the exciton with applied electric field [the quantum confined Stark effect (QCSE)] is obtained in the stepped QWs as compared to a conventional square QW. However, no meaningful increase in optical modulation performance is found, due to broadening of the exciton transition in the stepped QWs. All MQWs contained nominal 45 A(ring) Al0.3Ga0.7As barriers. Single-step QWs consisted of a 15 A(ring) GaAs region with an 85 A(ring) Al0.1Ga0.9As step. Double-step QWs consisted of a central Al0.15Ga0.85As plateau, with 20 A(ring) GaAs regions on either side. The square QW consisted of 90 A(ring) of GaAs. Excellent agreement between measured QCSE and tunneling resonance calculations was found. Our results indicate that stepped MQW devices are intrinsically more susceptible to growth induced degradation than square MQW modulators. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360297
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  • 2
    Electronic Resource
    Electronic Resource
    GaAs-AlAs low-voltage refractive modulator operating at 1.06 μm (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 744-746 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have produced a nonabsorbing surface-normal optical modulator operating at 1.06 μm (e.g., for a high-power Nd-YAG pump laser) which has a relative transmission change of 16% for −1 to 1 voltage swing. The structure is a GaAs-AlAs dielectric mirror with alternating n- and p-type δ doping at each interface. Doping selective contacts are made to the sample so that an applied voltage appears equally across each period of the device, yielding a strong field which changes the index of the GaAs and hence shifts the mirror.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103432
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  • 3
    Electronic Resource
    Electronic Resource
    Fast escape of photocreated carriers out of shallow quantum wells (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 66-68 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report that at room temperature the field-induced escape of photogenerated carriers out of shallow GaAs/AlxGa1−xAs multiple quantum wells is as fast as for pure GaAs of the same thickness, if the value of x does not exceed 0.04. Our experimental findings can be explained by assuming that carriers are efficiently scattered into the unconfined barrier states by absorption of a LO phonon, as long as the effective barrier height is less than the LO-phonon energy. The application of shallow quantum wells with x≤0.04 in self-electro-optic effect devices, providing not only strong excitonic electroabsorption but also fast sweep-out times at small biases, should lead to shorter switching times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105524
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  • 4
    Electronic Resource
    Electronic Resource
    Spin relaxation and thermalization of excitons in GaAs quantum wells (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1902-1904 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results on the picosecond dynamics of spin relaxation and thermalization of excitons in GaAs quantum wells. The spin relaxation time constant is ≈50 ps for resonant excitation and less than 10 ps for nonresonant excitation, considerably shorter than those for free electrons in the bulk. Photoexcited cold, nonthermal excitons thermalize in ≈50 ps at 10 K and less than 10 ps at 35 K. Exciton-acoustic phonon energy exchange rates are determined from these measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105068
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  • 5
    Electronic Resource
    Electronic Resource
    Excitonic electroabsorption in extremely shallow quantum wells (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2582-2584 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the remarkable observation of strong room-temperature excitonic features in the absorption spectra of GaAs-AlxGa1−xAs quantum wells (QWs) for values of x as low as 0.02. This has important implications for high-power modulators, since saturation intensities have been shown to be higher in QW modulators with low barriers. In addition, very shallow QWs have enhanced electroabsorption at small biases because of ease of ionization. In our p-i(multi-QW)-n device with x=0.02, we obtain a transmission change from 29% to 47% for a voltage change from +1 to −3 V.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103822
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  • 6
    Electronic Resource
    Electronic Resource
    Nondegenerate four-wave mixing in a semiconductor microcavity (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2650-2652 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of highly nondegenerate four-wave mixing from a semiconductor microcavity. The phase mismatch originating from the unique relationship between a beam incidence angle and its cavity resonance frequency was minimized by using a new method where both of pump and probe beams are obliquely incident. External efficiency of 1.6% was measured at 10 K for 1.5 THz frequency conversion of probe pulses by using 1 ps pump pulses of 55 pJ incident pulse energy. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120168
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  • 7
    Electronic Resource
    Electronic Resource
    Novel photovoltaic δ-doped GaAs superlattice structure (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2247-2249 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An asymmetric δ-doped GaAs structure is described which exhibits novel photovoltaic effects and low-intensity nonlinear optics. Of particular interest in this kind of structure is the ability to design the electro-optical and nonlinear optical properties and the material response time over a wide range by appropriate design of the doping profile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101138
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  • 8
    Electronic Resource
    Electronic Resource
    Symmetric self-electro-optic effect device: Optical set-reset latch (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 1419-1421 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate an integrated symmetric self-electro-optic effect device consisting of two quantum well p-i-n diodes electrically connected in series. The device acts as a bistable optical memory element with individual set (S) and reset (R) inputs and complementary outputs (optical S-R latch). The switching point is determined by the ratio of the two inputs, making the device insensitive to optical power supply fluctuations when both power beams are derived from the same source. The device also shows time-sequential gain, in that the state can be set using low-power beams and read out with subsequent high-power beams. The device showed bistability for voltages greater than 3 V, incident optical switching energy densities of ∼16 fJ/μm2, and was tested to a switching time of 40 ns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99134
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  • 9
    Electronic Resource
    Electronic Resource
    Tunable stimulated emission of radiation in GaAs doping superlattices (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 757-759 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tunable stimualted emission of radiation is achieved in AlxGa1−xAs/GaAs double heterostructures, in which the waveguiding GaAs region consists of a delta-doped doping superlattice. The low-temperature emission energy is 45 meV below the bulk band gap of GaAs for homogeneous optical excitation of the Fabry–Perot cavity. The emission energy is continuously tunable over 35 A(ring) by inhomogeneous excitation of the cavity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101797
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  • 10
    Electronic Resource
    Electronic Resource
    Shallow donors in very pure GaAs grown by gas source molecular beam epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1285-1287 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report photoluminescence and transport studies of a very pure GaAs layer grown by gas source molecular beam epitaxy methods. A peak mobility of 300 000 cm2/V s is observed at 60 K. A very shallow donor with binding energy less than 2 meV is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99999
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