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  • 1
    Electronic Resource
    Electronic Resource
    Coupled resonator vertical-cavity laser diode (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3020-3022 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the operation of an electrically injected monolithic coupled resonator vertical-cavity laser which consists of an active cavity containing InxGa1−xAs quantum wells optically coupled to a passive GaAs cavity. This device demonstrates modulation characteristics arising from dynamic changes in the coupling between the active and passive cavities. A composite mode theory is used to model the output modulation of the coupled resonator vertical-cavity laser. It is shown that the laser intensity can be modulated by either forward or reverse biasing the passive cavity. Under forward biasing, the modulation is due to carrier induced changes in the refractive index, while for reverse bias operation the modulation is caused by field dependent cavity enhanced absorption. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125220
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  • 2
    Electronic Resource
    Electronic Resource
    Intrinsic exciton transitions in GaN (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 455-461 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intrinsic excitonic transitions in GaN have been studied using a variety of spectroscopic measurements. Sharp spectral structures associated with intrinsic free excitons could be observed in photoluminescence, reflection, and absorption spectra. The energy positions of excitonic transitions in GaN epitaxial layers were found to be influenced by the residual strain resulting from lattice-parameter and thermal-expansion mismatches between the epilayers and the substrates. The values of the four principal deformation potentials of wurtzite GaN were derived by using the strain tensor components determined by x-ray measurements. The observation of spectral features involving the emission of LO phonons in absorption and photoluminescence excitation spectra at energies above exciton resonances indicate that a phonon-assisted indirect excitation process, which simultaneously generates a free exciton and a LO phonon, is a very significant and efficient process in GaN. The lifetime of the free excitons is found to be longer than the relaxation time of LO-phonon emission but much shorter than that of acoustic-phonon emission. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366660
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  • 3
    Electronic Resource
    Electronic Resource
    Femtosecond wave mixing experiments in ZnCdSe/ZnSe quantum wells (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1534-1536 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Extreme high order nonlinear diffracted signals are found in ZnCdSe/ZnSe quantum wells in two beam, self-diffraction geometry. Diffracted signals of all observed orders are shown to originate predominantly from excitonic resonances. Using four-wave mixing, an indication of hole-longitudinal optical phonon scattering between the heavy and the light hole states is found, and exciton-phonon interaction is studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112034
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature-dependent absorption measurements of excitons in GaN epilayers (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1981-1983 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical absorption measurements were performed on a series of thin GaN epilayers. Sharp spectral features were observed due to the 1s A and B exciton transitions. Using polarization dependent absorption, the C exciton transition was identified. A broad absorption feature was observed at ∼3.6 eV, which is attributed to indirect exciton-phonon absorption. The excitonic structure was found to persist well above room temperature. A fit to the Varshni formula yielded a temperature dependence of E(T)=E(T=0)−11.8×10−4T2(1414+T) eV for the A and B excitons. The exciton absorption linewidth was studied as a function of temperature, indicating that GaN exhibits very large exciton-phonon coupling. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119761
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  • 5
    Electronic Resource
    Electronic Resource
    "S-shaped" temperature-dependent emission shift and carrier dynamics in InGaN/GaN multiple quantum wells (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1370-1372 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report temperature-dependent time-integrated and time-resolved photoluminescence (PL) studies of InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic chemical vapor deposition. We observed anomalous emission behavior, specifically an S-shaped (decrease–increase–decrease) temperature dependence of the peak energy (Ep) for InGaN-related PL with increasing temperature: Ep redshifts in the temperature range of 10–70 K, blueshifts for 70–150 K, and redshifts again for 150–300 K with increasing temperature. In addition, when Ep redshifts, the spectral width is observed to narrow, while when Ep blueshifts, it broadens. From a study of the integrated PL intensity as a function of temperature, it is found that thermionic emission of photocarriers out of local potential minima into higher energy states within the wells is the dominant mechanism leading to the thermal quenching of the InGaN-related PL. We demonstrate that the temperature-induced S-shaped PL shift is caused by a change in the carrier dynamics with increasing temperature due to inhomogeneity and carrier localization in the InGaN/GaN MQWs. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122164
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  • 6
    Electronic Resource
    Electronic Resource
    Optical studies of GaN and GaN/AlGaN heterostructures on SiC substrates (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 740-742 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the results of spectroscopic studies on GaN based epitaxial materials on SiC substrates by metalorganic chemical vapor deposition. A variety of techniques has been used to study the optical properties of GaN epilayers and GaN/AlGaN heterostructures. Sharp spectral structures associated with the intrinsic free excitons were observed by photoluminescence and reflectance measurements from GaN based materials grown on SiC substrates. The residual strain was found to have a strong influence in determining the energies of exciton transitions. Picosecond relaxation studies of exciton decay dynamics suggest that an AlGaN cladding layer with a small mole fraction of AlN can be relatively effective in enhancing the radiative recombination rate for excitons by reducing the density of dislocations and suppressing surface recombination velocity in the GaN active layer for the GaN/AlGaN heterostructure samples. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117876
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  • 7
    Electronic Resource
    Electronic Resource
    Stimulated emission characteristics of InGaN/GaN multiple quantum wells: Excitation length and excitation density dependence (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3689-3691 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optically pumped stimulated emission (SE) from InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic chemical vapor deposition has been systematically studied as a function of excitation length (Lexc). Two distinct SE peaks were observed from these structures: one that originates at 425 nm at 10 K (430 nm at 300 K) and another that originates at 434 nm at 10 K (438 nm at 300 K). The SE threshold for the high-energy peak was observed to always be lower than that of the low-energy peak, but the difference was found to decrease greatly with increasing Lexc. A detailed study of the emission intensity of these two SE peaks as a function of excitation density shows that the two peaks compete for gain in the MQW active region. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122864
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  • 8
    Electronic Resource
    Electronic Resource
    High single-mode power observed from a coupled-resonator vertical-cavity laser diode (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4079-4081 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a monolithic coupled-resonator vertical-cavity laser with an ion-implanted top cavity and a selectively oxidized bottom cavity which exhibits single fundamental-mode operation. The output powers are as high as 6.1 mW with side mode suppression ratios greater than 30 dB. The sizes of the implant and oxide current apertures are shown to be important for demonstrating the required selectivity for the fundamental lasing mode. With a fixed bias current on the implant cavity and increasing oxide cavity current, mode switching from single-mode operation to multimode operation and back to single-mode operation was observed. The intensities of the fundamental and first transverse modes were calculated by solving a set of multimode rate equations. The calculation indicates that the observed mode switching can be identified with changes in the optical length of the oxide cavity with increasing pump current. The observed mode dynamics are unique to coupled-resonator vertical-cavity lasers. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1426254
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  • 9
    Electronic Resource
    Electronic Resource
    Q-switched operation of a coupled-resonator vertical-cavity laser diode (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1975-1977 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report Q-switched operation from an electrically injected monolithic coupled-resonator structure which consists of an active cavity with InGaAs quantum wells optically coupled to a passive cavity. The passive cavity contains a bulk GaAs region which is reverse biased to provide variable absorption at the lasing wavelength of 990 nm. Cavity coupling is utilized to effect large changes in output intensity with only very small changes in passive cavity absorption. The device is shown to produce pulses as short as 150 ps at repetition rates as high as 4 GHz. A rate equation approach is used to model the Q-switched operation yielding good agreement between the experimental and theoretical pulse shape. Small-signal frequency response measurements also show a transition from a slower (∼300 MHz) forward-biased modulation regime to a faster (∼2 GHz) modulation regime under reverse-bias operation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126227
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  • 10
    Electronic Resource
    Electronic Resource
    Temperature dependence of laser threshold in an InGaAsN vertical-cavity surface-emitting laser (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3391-3393 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present theoretical and experimental results for the temperature dependence of threshold current in an InGaAsN/GaAs vertical-cavity surface-emitting laser (VCSEL) operating at 1.3 μm under continuous-wave current injection. Using a microscopic many-body laser theory, good agreement with experimental data is obtained. The influence of radiative and nonradiative recombination processes on the threshold current–density is investigated theoretically. Also, comparison to a GaAs/AlGaAs VCSEL emitting at 850 nm is made. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1374484
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