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Quantum Electronics, IEEE Journal of

Issue 6 • Date June 2000

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Displaying Results 1 - 19 of 19
  • A probability-amplitude transfer matrix model for distributed-feedback laser structures

    Publication Year: 2000 , Page(s): 633 - 640
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB)  

    Two different treatments of spontaneous emission in distributed-feedback (DFB) lasers were found in the literature, but adequate explanations for the different treatments were not found. Using an approach that allows comparison of the two different treatments of spontaneous emission, we show that the different treatments can lead to different spectral predictions. The difference in spectral predictions is negligible in Fabry-Perot lasers and index-coupled DFB lasers. However, in truncated-well gain-coupled DFB lasers, the difference between the two treatments is noticeable, and one treatment is markedly better at fitting to data. The treatment that best fits the data is also the treatment that makes sense quantum-mechanically. View full abstract»

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  • Multiwavelength DFB laser array with integrated spot size converters

    Publication Year: 2000 , Page(s): 641 - 648
    Cited by:  Papers (5)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (322 KB)  

    We describe the design, fabrication, and performance of a five-element quarterwave-shifted distributed feedback laser array with monolithically integrated spot size converters intended for use as a multiple-wavelength source in dense wavelength-division telecommunications systems. Facet power in excess of 10 mW with less than 150 mA bias and longitudinal side mode suppression greater than 40 dB were routinely achieved. Narrow far-field full-width at half-maximum angles of 6.9/spl deg//spl times/16.3/spl deg/ provided 3.5-dB coupling loss into single-mode fiber with 1.0-dB misalignment tolerances of /spl plusmn/2.0 /spl mu/m. With /spl plusmn/10/spl deg/C thermal tuning, 22 1555-nm channels spaced by 50 GHz were accessed with this device. Thorough field evaluation indicates that such a device is consistent with manufacturing requirements. View full abstract»

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  • Principles of parametric temporal imaging. II. System performance

    Publication Year: 2000 , Page(s): 649 - 655
    Cited by:  Papers (13)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (215 KB)  

    For pt. I, see ibid., vol. 36, p. 430, April 2000. The waveform manipulation technique known as temporal imaging can expand or compress signals in time while maintaining the shape of their envelope profiles. The temporal imaging system is analogous to that of its spatial counterpart, with dispersive propagation performing the role of diffraction and quadratic phase modulation in time acting as a "time lens." Recent work has concentrated on time lenses produced by the parametric mixing of the dispersed input signal with a linearly chirped optical pump pulse because of the broad bandwidth, and thus fine temporal resolution, that can be obtained. In a previous paper, we presented the numerous parametric imaging configurations that are possible and drew temporal ray diagrams to illustrate their operation. In this paper, we study the performance of these systems. Resolution, field of view, number of resolvable features, and distortions particular to this approach are discussed. View full abstract»

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  • Polarization characteristics of fiber DFB lasers related to sensing applications

    Publication Year: 2000 , Page(s): 656 - 664
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB)  

    An experimental and theoretical investigation of how the polarization mode competition and beat frequency of Er-doped fiber distributed-feedback lasers depend on perturbations such as localized transverse forces, back reflections, or changes in pump polarization is reported. Good agreement between the experiments and a comprehensive theoretical model is obtained. Use of a dual-polarization laser as a transverse force sensor with a resolution on the order of 1-100 nN//spl radic/Hz above 20 Hz is also discussed. View full abstract»

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  • The spatial distribution of high-order harmonics from solid surface plasmas

    Publication Year: 2000 , Page(s): 665 - 668
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    Investigations have been performed on harmonic generation from solid-vacuum interfaces using a 2.2-ps 1054-nm laser pulse at maximum intensities of /spl sim/2/spl times/10/sup 17/ W/spl middot/cm/sup -2/. It is found that the divergence of the harmonics gradually increases at intensities between I/spl lambda//sup 2/=2/spl times/10/sup 15/ and 2/spl times/10/sup 16/ W/spl middot/cm/sup -2//spl middot//spl mu/m/sup 2/. We experimentally observe that the divergence of the harmonics decreases as the order of the harmonic increases. We also found that the divergence of the third harmonics emission is smaller for 2.2-ps pulsewidth for the driving lasers as compared with those for 100-ps pulsewidth lasers. View full abstract»

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  • The RC/sup 2/LED: a novel resonant-cavity LED design using a symmetric resonant cavity in the outcoupling reflector

    Publication Year: 2000 , Page(s): 669 - 673
    Cited by:  Papers (4)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB)  

    We present the concept of a novel resonant-cavity LED design where a symmetric resonant cavity (RC) is added to the outcoupling reflector. Because of the peculiar characteristics of the resulting mirror, these so-called RC/sup 2/LED's have a much higher extraction efficiency into a limited NA as compared to conventional RCLED designs. View full abstract»

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  • Obtaining high efficiency at low power using a quantum-dot microcavity light-emitting diode

    Publication Year: 2000 , Page(s): 674 - 679
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (175 KB)  

    Efficiencies are calculated for quantum-dot apertured-microcavity light-emitting diodes. Although the maximum efficiency depends strongly on the quantum-dot inhomogeneous broadening, greater than 20% efficiency is calculated for a small-sized apertured microcavity, even for an inhomogeneous linewidth as large as 30 meV. The efficiency can be increased to 40% if the inhomogeneous linewidth is reduced to 10 meV and to more than 60% if the inhomogeneous linewidth is eliminated to leave a homogeneous linewidth of 6.6 meV. The maximum output powers are /spl sim/40 nW, although a microarray can increase this value. For the case of a single quantum dot, an efficiency >80% is estimated for a submicron apertured-microcavity, with a maximum output power of /spl sim/3 nW. View full abstract»

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  • Pump-probe experiments at 1064 nm in singlewall carbon nanotube suspensions

    Publication Year: 2000 , Page(s): 680 - 686
    Cited by:  Papers (11)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (126 KB)  

    Singlewall carbon nanotube (SWNT) suspensions have been shown to be good optical limiters mainly because of their nonlinear scattering properties. In this paper, we report on a pump-probe experiment coupled with emission measurements for SWNT's in two solvents (water and chloroform). Time-resolved probe transmission with a pump at 1064 nm and a CW probe at 633 nm permits one to associate optical limiting with the formation of bubbles in the solvent, sublimation of the particles, and cavitation effects at high fluences. We show that the optical limiting behavior of SWNT's for nanosecond pulse duration is better in chloroform than in water due to different thermodynamic properties of the solvents. View full abstract»

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  • Compensation of nonlinear self-focusing in high-power lasers

    Publication Year: 2000 , Page(s): 687 - 691
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB)  

    We report on experimental results and the numerical modeling of the compensation of nonlinear self-focusing effects occurring in a high-power Nd:glass laser system at intensities above 1 GW/cm/sup 2/. A GaAs wafer with a negative nonlinear refractive index was used for the cancellation of the accumulated phase difference along the beam direction in a nonlinear medium (B integral). A numerical model is developed to calculate the behavior of the experimental setup. View full abstract»

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  • Theoretical analysis of the photocurrent dark decay in photorefractive media

    Publication Year: 2000 , Page(s): 692 - 697
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (181 KB)  

    The photocurrent dark decay in photorefractive materials is theoretically analyzed by using two different dynamical approaches-namely, the shallow traps and electron-hole transport models. The analysis is based on experimental results that show a double exponential decay of the photocurrent with short pulsed or continuous excitation. Expressions for the photocurrent amplitudes and decay times have been derived in terms of material and excitation parameters. Several dynamic behaviors are predicted for both models. View full abstract»

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  • Pulse evolution in a photorefractive self-pumped phase conjugator with transmission grating geometry

    Publication Year: 2000 , Page(s): 698 - 701
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB)  

    The effect of grating dispersion on pulse evolution in a photorefractive self-pumped phase conjugator is analyzed. The broadening factors and the time-dependent phases of self-pumped phase-conjugate pulses of unchirped and chirped Gaussian pulses are obtained. When the grating dispersion and the angular dispersion cancel the material dispersion, the self-pumped phase-conjugate pulse has a minimum width, which is determined by the first-order dispersion of the grating. The self-pumped phase conjugation of an unchirped Gaussian pulse broadens and is linearly chirped whereas the self-pumped phase conjugation of a chirped Gaussian pulse is compressed when the dispersion-induced chirp cancels the initial chirp. View full abstract»

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  • Electrorefraction associated with Wannier-Stark localization in strongly coupled three-quantum-well structures

    Publication Year: 2000 , Page(s): 702 - 707
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB)  

    Wannier-Stark localization of heavy holes and the associated refractive index changes in a strongly coupled GaAs-Al/sub 0.75/Ga/sub 0.25/As three-quantum-well structure have been investigated. Electroabsorption has been measured for TE polarization and the results compared with simulations performed by the exciton Green's function method to reveal the dominant contributions to the differential absorption at low applied electric field. The refractive index changes calculated by Kramers-Kronig transformation are large compared with those arising from the quantum-confined Stark effect in conventional square quantum wells and are shown to derive from the emergence of only first-order ladder states due to the strong localization of heavy holes. Preliminary experimental confirmation of strong electrorefraction associated with heavy-hole state localization is obtained at 80 meV detuning. This effect is potentially useful for electrooptic device applications. View full abstract»

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  • Spectral properties of amplified spontaneous emission in semiconductor optical amplifiers

    Publication Year: 2000 , Page(s): 708 - 720
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (638 KB)  

    We present a theoretical investigation of the spectral properties of spontaneous emission in semiconductor optical amplifiers. We use an extended (3/spl times/3) transfer matrix formalism to derive in the spectral domain an expression for the total longitudinally averaged internal field, which is valid regardless of the levels of optical input and bias current. The material parameters are saturated not only by the monochromatic signal, but also by the amplified spontaneous emission, filtered into the resonance modes of the structure, and integrated over its whole spectral range. View full abstract»

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  • Novel technique for the systematic measurement of gain, absolute refractive index spectra, and other parameters of semiconductor lasers

    Publication Year: 2000 , Page(s): 721 - 727
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    To characterize semiconductor lasers, it is often required to measure parameters such as the quasi Fermi-level separation, intrinsic optical loss, the position of the gain peak, and gain and absolute refractive index spectra. For these measurements, there are many different techniques available, but they neglect to take into account the dispersion of refractive index and cannot be used to extract the absolute refractive index spectrum. A novel technique is proposed to systematically and accurately measure all these parameters of semiconductor lasers. Compared with techniques often used, which will be briefly reviewed in the paper, this novel technique has the following advantages: (1) the determination process uses only the measured spontaneous emission spectra, without the requirement for knowledge of such parameters as intrinsic optical loss, facet reflectivity, and waveguide confinement factor, which presently are difficult to check experimentally; (2) results are obtained for each given current (for example, this technique measures intrinsic optical loss for each given current, rather than the average one over the whole current range); (3) the dispersion of refractive index is taken into account; (4) both the absolute refractive index spectrum for a given current and its change with current can be accurately measured; (5) the gain spectra and refractive index can be measured as wide as one wants; (6) the measurement accuracy is improved; and (7) no adjustable parameter or recalibration is needed. View full abstract»

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  • 1.3-/spl mu/m InAsP modulation-doped MQW lasers

    Publication Year: 2000 , Page(s): 728 - 735
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (197 KB)  

    The effect of both n-type and p-type modulation doping on multiple-quantum-well (MQW) laser performances was studied using gas-source molecular beam epitaxy (MBE) with the object of the further improvement of long-wavelength strained MQW lasers. The obtained threshold current density was as low as 250 A/cm/sup 2/ for 1200-/spl mu/m-long devices in n-type modulation-doped MQW (MD-MQW) lasers. A very low CW threshold current of 0.9 mA was obtained in 1.3-/spl mu/m InAsP n-type MD-MQW lasers at room temperature, which is the lowest ever reported for long-wavelength lasers using n-type modulation doping, and the lowest value for lasers grown by all kinds of MBE in the long-wavelength region. Both a reduction of the threshold current and the carrier lifetime in n-type MD MQW lasers caused the reduction of the turn-on delay time by about 30%. The 1.3-/spl mu/m InAsP strained MQW lasers using n-type modulation doping with very low power consumption and small turn-on delay time are very attractive for laser array applications in high-density parallel optical interconnection systems. On the other hand, the differential gain was confirmed to increase by a factor of 1.34 for p-type MD MQW lasers (N/sub A/=5/spl times/10/sup 18/ cm/sup -3/) as compared with undoped MQW lasers, and the turn-on delay time was reduced by about 20% as compared with undoped MQW lasers. These results indicate that p-type modulation doping is suitable for high-speed lasers. View full abstract»

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  • Gain measurements on GaAs-based quantum cascade lasers using a two-section cavity technique

    Publication Year: 2000 , Page(s): 736 - 741
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    A two-section cavity device has been used to measure gain spectra and waveguide losses of a GaAs-based quantum cascade laser. The device operates at 8.9 /spl mu/m and optical confinement is obtained by means of Al-free cladding layers. We investigated the gain characteristics in a spectral window of /spl sim/60 meV and up to 200 K. For current densities ranging from 1 to 8 kA/cm/sup 2/, we report a constant gain coefficient of 13 cm/kA at 4 K and 6 cm/kA at 200 K. At low temperatures and for current densities above 8 kA/cm/sup 2/, we observe gain saturation which we attribute to a reduced electron injection in the active region caused by space charge effects. We report a value of 22 cm/sup -1/ for the waveguide losses in good agreement with previous measurements. View full abstract»

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  • Minority carrier effects in GaInP laser diodes

    Publication Year: 2000 , Page(s): 742 - 750
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (170 KB)  

    Using a top-contact window, we have observed emission from a direct-gap monitor layer placed at the interface between the p-cladding and contact layers of an AlGaInP laser diode when driven under forward bias, thereby providing direct evidence for minority carrier (electron) leakage in these devices. We have further shown that the leakage is due to both drift and diffusion and, using pulsed optical excitation of a device under bias, we have determined a value of 170/spl plusmn/10 cm/sup 2/ V/sup -1/ s/sup -1/ for the mobility of minority carriers in the p-type cladding layer by a time-of-flight experiment. The data was analyzed using a simulation which takes account of the influence of recombination times in the well and monitor layer on the overall time response of the structure. The measured mobility corresponds to electron transport through the X-conduction band. We show that the drift component of the leakage current reduces the differential efficiency and is responsible for the decrease in external differential efficiency with increasing temperature. Because the leakage occurs by a mixture of drift and diffusion, the transit time does not decrease significantly with increasing drive current; however the impact of leakage on the modulation response is predicted to be very small unless the leakage becomes a substantial fraction of the total current. View full abstract»

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  • Diode-pumped Nd:YAG laser producing 122-W CW power at 1.319 /spl mu/m

    Publication Year: 2000 , Page(s): 751 - 756
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (162 KB)  

    A high-power diode-pumped Nd:YAG laser oscillating at a wavelength of 1.319 /spl mu/m is reported. A 122-W CW laser beam with an M2 factor of 35 has been achieved with an optical efficiency of 19.6%. The lasing characteristics, including thermal lensing, at 1.319 /spl mu/m are compared with those at 1.06 /spl mu/m. Under lasing conditions, the focal length of thermal lensing at 1.319 /spl mu/m decreases by 25% and increases by 15% at 1.06 /spl mu/m with respect to the nonlasing conditions. Based on the experimental results, the heat dissipation in an Nd:YAG rod is discussed with reference to nonradiative transitions from the upper laser level. View full abstract»

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  • Self-adjusting compensating thermal lens to balance the thermally induced lens in solid-state lasers

    Publication Year: 2000 , Page(s): 757 - 764
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB)  

    The thermal lens is a critical issue, particularly in high-power diode-pumped solid-state laser rods. A self-adjusting scheme for compensation of the thermally induced lens is presented. The requirements for such an element and its influence on the resonator are discussed. With an appropriate compensating element and a suitable resonator design, constant beam parameters are expected to be achieved over a pump range of several kilowatts. 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..

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Meet Our Editors

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