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Quantum Electronics, IEEE Journal of

Issue 1 • Date Jan. 2003

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Displaying Results 1 - 23 of 23
  • Introduction to the feature section on optical spatial solitons

    Publication Year: 2003 , Page(s): 1 - 2
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    Freely Available from IEEE
  • Reflectionless multichannel wavelength demultiplexer in a transmission resonator configuration

    Publication Year: 2003 , Page(s): 160 - 165
    Cited by:  Papers (14)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (318 KB) |  | HTML iconHTML  

    A wave demultiplexer system with N channels in a two-dimensional photonic crystal is proposed. The demultiplexer is realized by the coupling among an ultra-low-quality factor microcavity and N resonators with high-quality factor. The coupling mode theory is employed to analyze the behavior of this system. The analytic results reveal that the reflection is fully absent at the peak frequencies for all channels. The simulations obtained by multiple-scattering method and experimental results in the microwave region show that the analysis is valid. This method might also be valuable for the design of other all-optical functional circuits. View full abstract»

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  • Microscopic simulation of the temperature dependence of static and dynamic 1.3-μm multi-quantum-well laser performance

    Publication Year: 2003 , Page(s): 120 - 129
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB)  

    The temperature dependence of the performance of 1.3-μm Fabry-Perot (FP) multiple-quantum-well (MQW) lasers is analyzed using detailed microscopic simulations. Both static and dynamic properties are extracted and compared to measurements. Devices with different profiles of acceptor doping in the active region are studied. The simulation takes into account microscopic carrier transport, quantum mechanical calculation of the optical and electronic quantum well properties, and the solution of the optical mode. The temperature dependence of the Auger coefficients is found to be important and is represented by an activated form. Excellent agreement between measurement and simulation is achieved as a function of both temperature and doping profile for static and dynamic properties of the lasers, threshold current density, and effective differential gain. The simulations show that the static carrier density, and hence the contribution to the optical gain, varies significantly from the quantum wells on the p-side of the active layer to those on the n-side. Furthermore, the modal differential gain and the carrier density modulation also vary. Both effects are a consequence of the carrier dynamics involved in transport through the MQW active layer. Despite the complexity of the dynamic response of the MQW laser, the resonance frequency is determined by an effective differential gain, which we show can be estimated by a gain-weighted average of the local differential gain in each well. View full abstract»

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  • Theoretical analysis of laterally emitting terahertz-wave generation by difference-frequency generation in channel waveguides

    Publication Year: 2003 , Page(s): 166 - 171
    Cited by:  Papers (4)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB) |  | HTML iconHTML  

    Theoretical analysis of top- and side-emitting terahertz-wave generation by difference frequency generation in LiNbO3 channel waveguides with domain-inverted grating is presented. The analysis is based on Green's function and plane-wave expansion approaches. Mathematical expressions and numerical data for the conversion efficiency and the directionality were obtained. The results are consistent with those using two-dimensional model, but are more accurate and apply for various realistic device configurations. It was shown that higher efficiencies can be accomplished with narrow channel guides, although the radiation is highly divergent. View full abstract»

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  • A theoretical treatment of the subband population in the intersubband staircase laser

    Publication Year: 2003 , Page(s): 130 - 134
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    A theoretical study of the subband occupation in an intersubband staircase laser has been performed within the density-matrix approach by applying a canonical transformation to a tight-binding model of a superlattice with four quantum wells per unit cell. The field-induced carrier redistribution in a superlattice structure is investigated, for which recently mid-infrared laser operation has been demonstrated. An intrinsic population inversion occurs, which is due to resonant tunneling. View full abstract»

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  • 100-mW kink-free blue-violet laser diodes with low aspect ratio

    Publication Year: 2003 , Page(s): 135 - 140
    Cited by:  Papers (18)  |  Patents (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (534 KB) |  | HTML iconHTML  

    400-nm-band GaN-based laser diodes (LDs) operating with a kink-free output power of over 100 mW and having a low aspect ratio of 2.3 have been successfully fabricated for the first time. A new ridge structure, in which the outside of the ridge is covered with a stacked layer of Si on SiO2 and the ridge width is as narrow as 1.5 μm, is applied to realize high kink-free output power with a wide beam divergence angle parallel to the junction plane. A new layer structure around the active layer is demonstrated to be quite effective for obtaining a narrow beam divergence angle perpendicular to the junction plane, maintaining low threshold current. Ten LDs with low aspect ratio have been operated stably for over 1000 h under 30-mW continuous-wave operation at 60°C. Relative intensity noise measured under optical feedback with high-frequency modulation is as low as -125 dB/Hz. These results indicate that this LD is suitable for next-generation high-density optical storage systems. View full abstract»

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  • Efficient selection of high-order Laguerre-Gaussian modes in a Q-switched Nd:YAG laser

    Publication Year: 2003 , Page(s): 74 - 82
    Cited by:  Papers (16)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1033 KB)  

    Intra-cavity binary phase elements are incorporated into a Q-switched Nd:YAG laser resonator to obtain efficient high-order transverse mode selection. The resonator configuration is analyzed using the propagation-matrix diagonalization method and the Fox-Li algorithm, and a simple model for predicting the relative output powers of the selected modes is developed. The predicted results are verified experimentally with binary phase elements for selecting the TEM01, TEM02 and TEM03, degenerate Laguerre-Gaussian modes. The output energy per pulse was 15 mJ for the TEM01, 16.5 mJ for TEM02 and 18.3 mJ for TEM03, all higher than the 10 mJ for the TEM00. The performance in Q-switched operation was found to be similar to that in free-running operation. The numerical calculations, experimental procedure and experimental results are presented. View full abstract»

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  • Focal shift and focal switch of flattened Gaussian beams in passage through an aperture bifocal lens

    Publication Year: 2003 , Page(s): 172 - 178
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (525 KB)  

    A detailed study of the focal shift and accompanying focal switch of flattened Gaussian beams (FGBs) passing through an aperture bifocal lens is presented. It is shown that by suitably choosing the parameters of the optical system and beam, there exists two axial irradiance maxima for focused FGBs, which vary with the Fresnel number of the aperture. The focal switch can take place when the Fresnel number decreases gradually. The focal switch of Gaussian beams is treated as a special case of FGBs. From the axial irradiance distribution of focused FGBs, a physical explanation of the focal switch is given. A comparison with previous work is also made. View full abstract»

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  • Nonlinear polarization rotation in semiconductor optical amplifiers: theory and application to all-optical flip-flop memories

    Publication Year: 2003 , Page(s): 141 - 148
    Cited by:  Papers (88)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    We present a model for polarization-dependent gain saturation in strained bulk semiconductor optical amplifiers. We assume that the polarized optical field can be decomposed into transverse electric and transverse magnetic components that have indirect interaction with each other via the gain saturation. The gain anisotropy due to tensile strain in the amplifier is accounted for by a population imbalance factor. The model is applied to a nonlinear polarization switch, for which results are obtained, that are in excellent agreement with experimental data. Finally, we describe an all-optical flip-flop memory that is based on two coupled nonlinear polarization switches. View full abstract»

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  • Features of vectorial modes in phase-coupled VCSEL arrays: experiments and theory

    Publication Year: 2003 , Page(s): 109 - 119
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1279 KB) |  | HTML iconHTML  

    We present a detailed study of oxide-confined, vertical-cavity surface-emitting lasers (VCSELs) where the reflectivity of the top mirror has been patterned by means of a metal grid, which at the same time acts also as an electrode. Owing to their features, these kind of devices are commonly referred to as phase-coupled VCSEL arrays. The analysis is based on a joint experimental and theoretical effort: the former is devoted to a complete characterization of the emission properties, while the latter is based on a comprehensive fully vectorial model for the structure eigenmodes with the details of their complex structure. The detected characteristics make them quite attractive for various applications and the comparison of their modal properties with the model is proved to be essential for a deep understanding of these lasers. In particular, we observed and explain, for the first time, a characteristic behavior of the lasing array, which displays spatially inhomogeneous polarization characteristics with symmetry properties with respect to the array diagonals. The good matching between theory and experiment opens new perspectives for an optimized device, where the typical four lobe far-field emission is converted in a narrow central lobe: two different proposals will be discussed. View full abstract»

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  • Femtosecond self-doubling optical parametric oscillator based on KTiOAsO4

    Publication Year: 2003 , Page(s): 65 - 67
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    We report a femtosecond intracavity-frequency-doubled optical parametric oscillator that employs a single KTiOAsO4 crystal for both parametric generation and frequency doubling. This device generates a yellow output beam at 575 nm with 39.4% power conversion efficiency when synchronously pumped by a femtosecond Ti:sapphire laser at a wavelength of 796 nm. An intracavity retarder is employed to alleviate temporal pulse overlap problems associated with group velocity mismatch inside the KTiOAsO4 crystal. View full abstract»

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  • Photorefractive solitons

    Publication Year: 2003 , Page(s): 3 - 12
    Cited by:  Papers (30)
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    We present a review of recent works on spatial optical solitons in photorefractive media. We discuss fundamental properties of screening solitons and their interaction. View full abstract»

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  • A sequentially self-seeded Fabry-Perot laser for two-dimensional encoding/decoding of optical pulses

    Publication Year: 2003 , Page(s): 83 - 90
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB) |  | HTML iconHTML  

    Multiwavelength optical pulse trains with variable two-dimensional (2-D) code patterns formed by a single encoder have been generated from a self-seeded gain-switched Fabry-Perot (F-P) laser for the first time. Mechanically tunable cascaded fiber Bragg gratings (FBG) are used to construct the reconfigurable encoder, which acts as a discrete nonlinear dispersive component in the subharmonically pulse-gated external cavity of the laser to generate multiwavelength pulse trains with a variable 2-D code pattern defined by the settings of the FBG string. Four distinct repetitive patterns (corresponding to four different 2-D codes) of optical pulse trains, each made up of up to four pulses generated sequentially with different wavelengths, have been produced at a repetition rate of 250 MHz. The output pulses obtained by this method are much more intense and stable than those obtained from a free-running F-P laser. Furthermore, the different pulse patterns obtained show that the scheme can allow easy switching among different 2-D codes by simply reconfiguring the FBG string. Hence this laser with the embedded reconfigurable encoder should be a viable optical source for incoherent 2-D fiber-optic code-division multiple access (FO-CDMA) applications. Near-error-free transmission of data at 250 Mbit/s employing this laser/encoder over 9.5 km standard single mode fiber has been successfully demonstrated, thus confirming its performance and viability for FO-CDMA. View full abstract»

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  • Quadratic solitons: recent developments

    Publication Year: 2003 , Page(s): 22 - 30
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (718 KB) |  | HTML iconHTML  

    Multicolor optical solitons mediated by quadratic nonlinearities have been observed experimentally during the last few years in a variety of materials and geometries in a number of laboratories around the world. Today, many of the basic properties of the corresponding soliton families are theoretically well established. Nevertheless, experiments continuously reveal new surprises, and the topic is entering new theoretical and experimental territories. In this paper, we briefly outline the key features of the quadratic solitons and overview the latest developments. View full abstract»

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  • High-power integrated superluminescent light source

    Publication Year: 2003 , Page(s): 149 - 153
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (358 KB) |  | HTML iconHTML  

    In order to increase the optical output power of semiconductor superluminescent device, a direct coupling method had been used to integrate, monolithically, the superluminescent diode with a semiconductor optical amplifier. By this means, two kinds of integrated superluminescent light source have been fabricated. High output power was obtained in pulsed operation. View full abstract»

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  • Development of a diode-pumped Kerr-lens mode-locked Cr:LiSAF laser

    Publication Year: 2003 , Page(s): 68 - 73
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (346 KB) |  | HTML iconHTML  

    Kerr-lens mode-locked Cr:LiSrAlF6 lasers are demonstrated with various prism pairs based on a recalculation of the condition for compensating the intracavity dispersion. The minimum pulse duration is 9.9 fs, which is the limit for ordinary nonchirped dielectric mirrors. To develop an efficient diode-pumped Kerr-lens mode-locked Cr:LiSAF laser, diode-pumping geometry is also discussed. View full abstract»

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  • Spatial solitons in nematic liquid crystals

    Publication Year: 2003 , Page(s): 13 - 21
    Cited by:  Papers (65)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (759 KB) |  | HTML iconHTML  

    Nematic liquid crystals exhibit a saturable nonlinearity, nonlocal in time and in space, owing to light-induced reorientation of the molecular director. In such media, (2 + 1)-dimensional spatial solitons can be obtained at milliwatt-power levels and confine weaker co-polarized signals of different wavelengths, employing either coherent or partially incoherent excitations. Our experimental observations of solitons and related phenomena, ranging from angular steering to mutual interactions, are reviewed. Models are briefly discussed and used to predict and interpret the results. View full abstract»

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  • Spatial solitons in optical cavities

    Publication Year: 2003 , Page(s): 51 - 64
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1023 KB) |  | HTML iconHTML  

    We discuss the existence and the stability properties of spatial solitons, which are excited in externally driven nonlinear resonators. First, we give a short derivation of the basic equations we use to describe the field dynamics in a Fabry-Perot cavity. Then we show how the range of existence of cavity solitons is related to the stability properties of respective continuous wave solutions. Theoretical predictions are illustrated by numerical results and experimental findings. View full abstract»

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  • Effects of the spatial nonuniformity of optical transverse modes on the modulation response of vertical-cavity surface-emitting lasers

    Publication Year: 2003 , Page(s): 99 - 108
    Cited by:  Papers (13)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    We present detailed numerical simulations to clarify the important role that the nonuniformity of the transverse optical mode plays for the high-speed response of oxide-confined vertical-cavity surface-emitting lasers (VCSELs). The comprehensive laser diode simulator, Minilase, as well as a one-dimensional rate equation model are used as simulation tools. It is demonstrated that, due to the nonuniform optical intensity, carriers at different locations in the quantum well have different stimulated recombination rates, and therefore exhibit different dynamic responses to small signal modulation. This nonuniformity causes an overdamping of the relaxation oscillation, as well as a low-frequency roll-off of the modulation response. Due to this nonlinear effect, the intrinsic maximum bandwidth of VCSELs with oxide confined apertures is shown to be much smaller than predicted by the conventional rate equation model which assumes uniform optical intensity. We further demonstrate that this damping effect can be greatly reduced by restricting the current injection to be well within the transverse optical field. This is achievable by using tapered oxides to make the electrical aperture smaller than the optical aperture, which thereby improves the modulation bandwidth significantly. View full abstract»

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  • Optimization of refractive index sampling for multichannel fiber Bragg gratings

    Publication Year: 2003 , Page(s): 91 - 98
    Cited by:  Papers (36)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (721 KB) |  | HTML iconHTML  

    A comprehensive analysis of multichannel grating optimization strategies is presented. The central idea is in dephasing of partial gratings with respect to each other. This dephasing allows the utilization of ultraviolet-induced refractive index changes with maximum efficiency. The dependence of group delay ripple on optimization strategy, number of channels, and other grating characteristics is also briefly discussed. Finally, we discuss further generalization of the dephasing approach to the case of multichannel gratings with nonidentical spectral characteristics. View full abstract»

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  • Spatial optical solitons in waveguide arrays

    Publication Year: 2003 , Page(s): 31 - 50
    Cited by:  Papers (96)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2092 KB)  

    We overview theoretical and experimental results on spatial optical solitons excited in arrays of nonlinear waveguides. First, we briefly summarize the basic properties of the discrete nonlinear Schrodinger (NLS) equation frequently employed to study spatially localized modes in arrays, the so-called discrete solitons. Then, we introduce an improved analytical model that describes a periodic structure of thin-film nonlinear waveguides embedded into an otherwise linear dielectric medium. Such a model of waveguide arrays goes beyond the discrete NLS equation and allows studying many new features of the nonlinear dynamics in arrays, including the complete bandgap spectrum, modulational instability of extended modes, different types of gap solitons, the mode oscillatory instability, the instability-induced soliton dynamics, etc. Additionally, we summarize the recent experimental results on the generation and steering of spatial solitons and diffraction management in waveguide arrays. We also demonstrate that many effects associated with the dynamics of discrete gap solitons can be observed in a binary waveguide array. Finally, we discuss the important concept of two-dimensional (2-D) networks of nonlinear waveguides, not yet verified experimentally, which provides a roadmap for the future developments of this field. In particular, 2-D networks of nonlinear waveguides may allow a possibility of realizing useful functional operations with discrete solitons such as blocking, routing, and time gating. View full abstract»

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  • Optical amplification at 1534 nm in erbium-doped zirconia waveguides

    Publication Year: 2003 , Page(s): 154 - 159
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    We have developed planar waveguides with net gain in erbium-doped zirconia. Ion-beam sputtering was used to deposit amorphous high-refractive-index zirconia films, which were fabricated into single-mode waveguides. By adjusting oxygen flow rates while sputtering, and annealing the films after deposition, waveguide losses were reduced to 0.45 dB/cm at 1534 nm. Erbium in the zirconia, added by co-sputtering, had a wide, 54-nm full-width at half maximum emission band centered at 1538 nm, which offers potential advantages for wideband amplification in wavelength division multiplexing systems. When pumped with 36 mW at 980 nm, a 6.5 cm long, 8.8 × 1019 cm-3 doped waveguide produced 2.95 dB of optical amplification at 1534 nm. This was enough to overcome the waveguide loss and produce a small amount of net gain. With a higher pump power, substantial net gain appeared to be possible. These results show that wide-bandwidth erbium-doped optical amplifiers should be possible in zirconia. View full abstract»

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  • Breakdown probabilities for thin heterostructure avalanche photodiodes

    Publication Year: 2003 , Page(s): 179 - 185
    Cited by:  Papers (18)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (415 KB) |  | HTML iconHTML  

    The recurrence theory for the breakdown probability in avalanche photodiodes (APDs) is generalized to heterostructure APDs that may have multiple multiplication layers. The generalization addresses layer-boundary effects such as the initial energy of injected carriers as well as the layer-dependent profile of the dead space in the multiplication region. Reducing the width of the multiplication layer serves to both downshift and sharpen the breakdown probability curve as a function of the applied reverse-bias voltage. In structures where the injected carriers have an initial energy that is comparable to the ionization threshold energy, the transition from linear mode to Geiger-mode is more abrupt than in structures in which such initial energy is negligible. The theory is applied to two recently fabricated Al0.6Ga0.4As-GaAs heterostructure APDs and to other homostructure thin GaAs APDs and the predictions of the breakdown-voltage thresholds are verified. 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..

Full Aims & Scope

Meet Our Editors

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