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Quantum Electronics, IEEE Journal of

Issue 12 • Date Dec. 1999

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Displaying Results 1 - 25 of 26
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  • Author Index

    Page(s): 1 - 10
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    Freely Available from IEEE
  • Subject index

    Page(s): 10 - 37
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  • All-optical switching due to cascaded second-harmonic generation in directional couplers with laterally varying phase mismatches

    Page(s): 1834 - 1842
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    The local normal mode approach is employed to analyze cascaded second-harmonic generation (SHG) in directional couplers with different phase mismatches in both waveguides. The couplers are assumed to be fabricated in ferroelectric crystals, which are periodically domain inverted with different periods in both waveguide regions. These components are proposed to imitate the switching in nonlinearly asymmetric third-order directional couplers by using the cascaded second-order effect, which can mimic third-order interactions with effective third-order nonlinearities proportional to the reciprocal phase mismatch. The results for the second-order directional couplers are compared to those for the respective ideal third-order ones View full abstract»

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  • Pulse compression to the subphonon lifetime region by half-cycle gain in transient stimulated Brillouin scattering

    Page(s): 1812 - 1816
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    A new approach to the transient pulse compression by stimulated Brillouin scattering (SBS) is presented. The theoretical analysis involving the time-dependent SBS gain in explicit form leads to a nonlinear system of partial differential equations, solved numerically by a generalization of the split-step method. It is shown theoretically and confirmed experimentally that the phonon lifetime is not always an appropriate parameter that determines the lower limit to the pulse duration in SBS compressors. A half-cycle gain regime is found for pulses shorter than the phonon lifetime. Hence, under proper conditions, pulses as short as half the acoustic period can be produced View full abstract»

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  • Electromagnetic modeling of quantum-well photodetectors containing diffractive elements

    Page(s): 1870 - 1877
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    An analytical approach for modeling optical fields in quantum-well infrared photodetectors was developed by using a rigorous solution of the corresponding electromagnetic problem. Its application includes structures having a large number of dielectric layers, which may contain gratings having arbitrary profiles and metal-strip arrays acting as electrodes. By representing the fields inside complex photodetector structures in terms of interconnected transmission-line units, this approach helps considerably to clarify the role of each constituent of the photodetector. Examples involving realistic situations reveal that the presence of metal electrodes may affect the photodetection operation in a large class of grating structures. In particular, we show that the sensitivity of specific photodetector configurations can be enhanced by choosing grating parameters that optimize the overall photodetecting performance View full abstract»

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  • Modeling of two-dimensional gain profiles for InP-InGaAs avalanche photodiodes with a stochastic approach

    Page(s): 1853 - 1862
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    The two-dimensional (2-D) gain profiles for separate absorption, grading, charge and multiplication (SAGCM) InP-InGaAs avalanche photodiodes (APD's) have been modeled with a stochastic approach. To consider the influence of the curved diffusion edge on the electric field within the periphery region, equations are derived from the cylindrical Poisson's equation. The electric field profiles are computed at various APD radii and the electric field in the multiplication layer is reduced significantly for APD's with a partial charge sheet in the periphery. It is demonstrated by the modeled 2-D gain profiles that the premature edge breakdown can be effectively suppressed for such devices. The modeled 2-D gain profiles for APD's with a partial charge sheet incorporated in the periphery are in good agreement with the experimental results. The results and the uniformity issue of the 2-D gain profiles are discussed. The effect of using curved diffusion interfaces instead of a steep mesa step is also explored; this suggests that the fabrication of a charge sheet mesa step may complicate the gain uniformity issue. From our analyses, we find that the uncertainty and the symmetry of both patterning the charge sheet mesa structure and controlling the diffusion interface between the p+ InP top layer and the n- InP multiplication layer are most likely to affect the uniformity and the symmetry of the 2-D gain profiles for the SAGCM InP-InGaAs APD's View full abstract»

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  • Lateral mode dynamics of semiconductor lasers

    Page(s): 1904 - 1911
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    The interaction between two lateral modes in a waveguide semiconductor laser is studied. The effects of carrier diffusion are included into the governing rate equations. A linear stability analysis is used to identify regions of frequency locking between the lateral modes. Numerical integration shows the effects of the diffusion length and other system parameters on the lateral mode dynamics. It is shown that variations in the carrier diffusion length give rise to regimes of single-mode dominance, oscillation, chaos, and frequency locking. Direct experimental observations of higher order lateral modes in lasers exhibiting beam instabilities are presented. Observations of bistable beam steering with hysteresis are presented and explained View full abstract»

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  • Measurements and modeling of reflective bistability in 1.55-μm laser diode amplifiers

    Page(s): 1894 - 1903
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    We present experimental measurements of bistable characteristics for the case of a 1.55-μm symmetric Fabry-Perot laser amplifier with a particularly rich variety of behavior for reflected signals. Three main forms of hysteresis loops are observed on reflection. The hysteresis loop changes from anticlockwise to clockwise hysteresis in the optical output-input characteristic when the drive current or initial phase detuning is changed. A “butterfly” hysteresis loop is observed experimentally at an optical input power as low as 300 μW for a drive current equal to 94% of the lasing threshold. The dependence of the reflective optical bistability on drive current, initial phase detuning, and injected optical pewter has been investigated for the first time in an uncoated 1.55-μm amplifier. Measurements of the device voltage shifts on switching reveal hysteresis loops which match those in the corresponding optical powers and which indicate the amount of gain saturation and nonlinear refraction responsible for bistability. An analytical model is used to describe the observed reflective bistability and to give insight into the detailed physical mechanisms responsible View full abstract»

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  • Extreme timing jitter reduction of a passively mode-locked laser diode by optical pulse injection

    Page(s): 1805 - 1811
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    Reduction of the timing jitter to less than that of the master laser pulses was achieved for a passively mode-locked laser diode stabilized by subharmonic-frequency optical pulse injection. Detailed investigation revealed that this phenomenon originates from the short-term stability of the mode locking frequency under passively mode-locking operation with suitable bias conditions of the saturable absorber and the gain sections View full abstract»

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  • Enhancement of third-order nonlinear optical susceptibilities in compressively strained quantum wells under the population inversion condition

    Page(s): 1817 - 1825
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    Third-order optical nonlinear susceptibilities χ(3) in compressively strained and nonstrained InGaAs-InGaAsP quantum wells (QW's) under the population inversion condition are discussed. The small effective mass of compressively strained QW's increases the contribution of the carrier density pulsation effect and the carrier heating effect of χ(3). The hole burning effect is also increased due to the decrease of the carrier-carrier scattering rate. The calculation including these effects shows an enhancement of factor 3 due to 0.8% compressive strain. The values of χ(3) are experimentally estimated from the data of nondegenerate four-wave mixing in λ/4-shifted distributed feedback lasers. χ(3) in 0.8% compressively strained QW's is three times larger than that in nonstrained QW's with the same linear gain View full abstract»

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  • Ge-on-Si approaches to the detection of near-infrared light

    Page(s): 1843 - 1852
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    We review our recent results on Ge-based near-infrared photodetectors grown on silicon. We fabricated metal-semiconductor-metal photodetectors based on epitaxial pure-Ge grown on silicon by chemical vapor deposition. Material characterization and device performances are illustrated and discussed. Exploiting a novel approach based on evaporation of polycrystalline-Ge on silicon, we also realized efficient near-infrared photodiodes with good speed and sensitivity. Finally, multiple-element devices were designed, fabricated, and tested, such as a voltage-tunable wavelength-selective photodetector based on a SiGe superlattice and a linear array of 16 photodetectors in poly-Ge on Si View full abstract»

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  • Determination of singlet-oxygen generator efficiency on a 10-kW class supersonic chemical oxygen-iodine laser (RADICL)

    Page(s): 1759 - 1764
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    With the advent of the Air Force Airborne Laser program, the emphasis of chemical oxggen-iodine laser (COIL) research has shifted toward improving the overall efficiency. A key component of the COIL is the singlet-oxygen generator (SOG). To assess the efficiency of the SOG, an accurate method of determining the yield of O2(a1 Δg), [O2(a1Δg )]/[O2(total)] where [O2(total)]=[O2 (a1Δg)]+[O2(X3 Σg-)], has been developed. Absorption measurements of ground-state oxygen utilizing the magnetic-dipole transition, O2(X3Σg-) (ν=0)→O2(b1Σg +)(ν=0) centered at 762 nm, have been obtained using a scanning diode laser in conjunction with a multiple-pass Herriott cell and balanced-ratiometric detection on the 10-kW class supersonic COIL (RADICL). A series of experiments was designed and conducted to test the efficiency of the SOG under various conditions View full abstract»

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  • Modeling of diode-pumped actively Q-switched lasers

    Page(s): 1912 - 1918
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    The intracavity photon density and initial population inversion density in the diode-pumped actively Q-switched laser rate equations are assumed to be Gaussian distributions. These space-dependent rate equations are solved numerically and a group of general curves are generated. By using these curves and the related formulas, the pulse parameters of an arbitrary actively Q-switched laser can be easily estimated and an optimally coupled Q-switched laser can be designed. A sample calculation for a Q-switched Nd3+:YVO4 laser is presented to demonstrate the use of the curves and the related formulas View full abstract»

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  • UV lasing on Cu+ in a Ne-CuBr pulsed longitudinal discharge

    Page(s): 1799 - 1804
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    UV lasing on copper ion transitions in CuBr vapor laser has been obtained in a nanosecond pulsed longitudinal discharge with Brewster windows and external mirrors. A record small-signal gain per unit length has been achieved (up to 19%/m and 16%/m for the 238.6- and 270.3-nm transitions, respectively). Infrared (IR) laser action on Cu ions in a He-CuBr discharge and on Ag ions in a He-AgI (silver iodide) discharge has also been observed. A maximum average output power of 430 mW has been achieved multiline (740.4-780.8 nm) on the Cu+ IR transitions. A maximal gain of 58%/m has been obtained on the strongest 780.8-nm transition View full abstract»

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  • High-reflectivity lead-salt-based Bragg mirrors for the mid-infrared range

    Page(s): 1753 - 1758
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    High-quality lead-salt-based Bragg mirror stacks were fabricated on BaF2(111) substrates by molecular beam epitaxy. The mirrors consisted of Pb1-xEuxTe quarter-wavelength layer pairs with 1% and 6% Eu content and were designed for use in mid-infrared (MIR) vertical emitting devices with a PbTe active zone. From theoretical simulations, we obtained the internal reflectivity with incidence from an active resonator medium and the reflectivity spectra of Bragg/metal mirror combinations. For a 32-layer pair mirror, we measured a record stopband reflectivity for the MIR of over 99% at 5.7 μm, in excellent agreement with our calculations View full abstract»

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  • Transverse optical mode patterns for an RF excited Ar-He-Xe laser

    Page(s): 1786 - 1798
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    Transverse optical modes for an RF excited Ar-He-Xe laser are studied both experimentally and theoretically. A diffraction model for a waveguide with a nonsaturable gain and refractive index gradients placed between two plane mirrors is formulated. The effects of gain and diffraction index gradients and of diffraction in free space are evaluated for typical experimental conditions. A direct comparison between theoretical mode patterns and experimentally measured ones at distances of 17 and 114 cm from the output mirror demonstrated a satisfactory agreement for various laser wavelengths and gas mixture compositions View full abstract»

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  • Theory of an amplified closed-Sagnac-loop interferometric fiber-optic gyroscope

    Page(s): 1777 - 1785
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    An amplified closed-Sagnac loop interferometric fiber optic gyroscope (AC-IFOG) has been proposed and demonstrated in our earlier work. This paper reports the theoretical analysis of its operation. The analysis has been focused on the effect of the erbium-doped fiber amplifier (EDFA) inserted within the reentrant path. The analysis shows that the sensitivity can be improved by at least two orders of magnitude as compared to a conventional IFOG if the EDFA is an ideal device. The simulated open-loop response coincides well with that of the experimental data. Further analysis shows that the detection limit is restricted by the beat noise that build ups rapidly in successive circulations. The rate of noise build-up depends greatly on the optical bandwidth of the closed-Sagnac loop View full abstract»

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  • High slope efficiency and low noise characteristics in tapered-active-stripe DFB lasers with narrow beam divergence

    Page(s): 1765 - 1770
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    We report high slope efficiency and low noise characteristics in a distributed feedback (DFB) laser lasing at 1.3 μm with narrow beam divergence by employment of a laterally tapered active stripe over the whole cavity. This tapered structure is designed to realize narrow beam divergence, low threshold current, and high longitudinal mode selectivity. The fabricated tapered-active-stripe DFB lasers demonstrated of 9.20×13.40 and a record slope efficiency, for a narrow beam DFB laser, of 0.59 mW/mA. The temperature characteristics from -10°C to 85°C shows high output power at high temperature, stable single longitudinal mode oscillation and stable far-field patterns. Furthermore, for the first time ever, a low relative intensity noise characteristic of under -155 dB/Hz has been realized when butt-coupling into a single-mode fiber View full abstract»

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  • Improved second-harmonic generation by selective Yb ion doping in a new nonlinear optical crystal YCa4O(BO3)3

    Page(s): 1826 - 1833
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    We describe experiments characterizing a new nonlinear optical crystal, YCa4O(BO3)3 (YCOB). This crystal has a number of advantages over other commonly available nonlinear optical crystals. It has a higher nonlinear coefficient than KDP, can be fabricated to large sizes (~3-in diameter, 8-in length), and has a high damage threshold. Moreover, this new nonlinear optical crystal is nonhygroscopic, has good optical quality and mechanical properties, allowing easy optical polishing. This crystal, YCa4 O(BO3)3, commonly termed YCOB, is one of a family of new nonlinear crystals, the oxyborates, that include RECa4O(BO3)3 (RE=La3+, La 3+, Y3+, Sm3+, Gd3+, Er3+, and Nd3+). In this paper, we also successfully demonstrate a technique for improving the nonlinear optical properties of this crystal. This technique, ion substitution, has previously had limited success with other crystal hosts. However, the inclusion of yttrium in YCOB provides the opportunity to exploit this technique. Yb3+, which has larger mass, but approximately the same atomic size as Y3+ can be substituted into the crystal structure without introducing stress and nonuniformities. A systematic investigation of the linear and nonlinear characteristics of several crystals doped with various levels of Yb demonstrate that selective substitution of Yb in YCa4O(BO3)3 improves the second-harmonic conversion efficiency by increasing the optical nonlinearity View full abstract»

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  • Tunneling time asymmetry in semiconductor heterostructures

    Page(s): 1887 - 1893
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    Analytical expressions are given for the difference between left-to-right and right-to-left tunneling times in asymmetric single- and multiple-barrier heterostructures. This tunneling time asymmetry is related to the phase difference of the reflection coefficients of the electron wavefunction for the two tunneling directions. Examples for single- and double-barrier heterostructures are given. The treatment in this paper can be used for designing devices with asymmetric frequency characteristics with respect to the electron tunneling direction View full abstract»

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  • Moving-focus versus self-waveguiding model for long-distance propagation of femtosecond pulses in air

    Page(s): 1771 - 1776
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    Experiments on focused femtosecond pulse propagation in air in the infrared which can test whether a strict moving-focus model interpretation is applicable were recently analyzed by Lange et al. Using numerical simulations, we show that filament propagation can be given a consistent interpretation in terms of the dynamic spatial replenishment model. While the moving-focus model cannot explain the persistence of a filament past the linear focus, the self-waveguiding model also presents problems of interpretation View full abstract»

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  • Novel edge suppression technique for planar avalanche photodiodes

    Page(s): 1863 - 1869
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    We present an advanced drift diffusion simulation of the joint opening effect (JOE) avalanche photodiode (APD). The joint opening effect APD is a new design for achieving edge breakdown suppression in planar avalanche photodiodes. It is a single growth process that achieves center breakdown dominance without the use of guard rings, partial charge sheets, or surface etches. The JOE APD only requires the diffusion of the primary well. Edge breakdown suppression is achieved by partially insulating the electric field growth in the active region from the geometry of the primary well 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