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Quantum Electronics, IEEE Journal of

Issue 3 • Date Mar 1992

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Displaying Results 1 - 23 of 23
  • Influence of facet reflection on the performance of a DFB laser integrated with an optical amplifier/modulator

    Page(s): 594 - 603
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    The influence of output facet reflection on characteristics of a monolithically integrated optical device consisting of a distributed feedback (DFB) laser and an optical amplifier/modulator is analyzed. Basic equations used for the analysis are the characteristic equation for a DFB laser and the rate equations. As a result, it is known that static and dynamic properties of such optical integrated devices are seriously degraded by the optical feedback from the output facet. It is concluded that the power reflectivity of the output facet should be reduced to at least less than 0.1% for the integrated region to work as an optical amplifier and less than 0.01% as an intensity modulator View full abstract»

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  • Generation of extended pulse trains of minimum duration by passive negative feedback applied to solid-state Q-switched lasers

    Page(s): 710 - 719
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    Intracavity self-focusing in a thin two-photon absorber acts, in combination with pinholes, as an efficient power and energy limiter in flashlamp (pulsed) and arc lamp (CW) pumped actively passively mode-locked crystalline Nd-doped lasers. Power limiting by the intracavity two-photon absorber is exploited to create the condition for optimum pulse compression in the saturable absorber. Additional pulse shortening is due to the elimination of the pulse tail by self-defocusing in the nonlinear crystal. Extracavity and intracavity measurements, as well as three-dimensional computer simulations, give a complete understanding of the pulse evolution in the cavity, including the two mechanisms of pulse shaping and compression View full abstract»

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  • Analysis of optical bistability in a nonlinear distributively coupled resonator

    Page(s): 585 - 589
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    A nonlinear distributively coupled resonator (NDCR) used as a bistable element is studied. The resonator is an integrated optics implementation of a nonlinear Fabry-Perot resonator with a variable reflectivity mirror. Under certain conditions, the intensity-dependent reflectivity and tuning of the resonator contribute constructively and enhance nonlinear properties of the device. Numerical methods are used to optimize NDCR design parameters and show that the critical intensity required for onset of bistability is reduced by 30% relative to a comparable regular Fabry-Perot. Similarly, the minimum required index change is reduced by 10% View full abstract»

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  • Oscillation modes of laser diode pumped hybrid bistable system with large delay and application to dynamical memory

    Page(s): 686 - 699
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    An electrooptical bistable system with a very large delay was constructed, and self-oscillation phenomena were investigated. Many multistable self-oscillation modes were observed, including second-order bifurcations of the 265th harmonic. The dynamical memory function was demonstrated by locking second order bifurcated modes to external clock oscillations and performing WRITE and READ of binary data sequences in the waveforms of the bifurcated modes. The nonlinear bifurcation phenomena in this system are applicable for large-capacity memory and signal processing. Spurious preferential excitation of particular harmonic modes was related to the fine structure in the transfer spectrum of the open loop associated with spurious resonances in the electrooptical modulator used as a nonlinear element View full abstract»

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  • A lead bromide laser operating at 722.9 and 406.2 nm

    Page(s): 590 - 593
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    A self-heated laser, operating on the atomic lead transitions at 722.9 and 406.2 nm is reported. The free lead atoms were produced by electric-discharge dissociation of lead bromide which was generated in situ by flowing a Ne-HBr gas mixture over molten Pb in the laser tube. The experimental technique may be applied readily to a number of metal-vapor lasers. Also reported is stable high-PRF operation on the 406.2 nm transition of lead View full abstract»

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  • Carrier collection efficiency effects and improvements of electroabsorption devices with different barrier structures

    Page(s): 670 - 677
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    Self-electrooptic effect devices (SEEDs) with both thick (60 Å) and thin (35 Å) quantum-well barriers were studied experimentally. Relevant device properties including responsivity, carrier collection efficiency, switching, and optical bistability behavior are compared. SEED modulator photocurrent and reflectivity data are analyzed and shown to predict S-SEED behavior. A simple yet powerful optical technique for measuring the light utilization efficiency and the carrier collection efficiency η is described and used to compare different device mesa sizes and barrier structures. The effects of η on device performance are expounded. For thin-barrier SEEDs, η is substantially improved, approaching 100%, even at bias voltages approaching zero and for small device structures View full abstract»

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  • The transfer function and impulse response of photorefractive two-beam coupling

    Page(s): 750 - 756
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    The transfer function and impulse response of photorefractive two-beam coupling are derived in the undepleted pump approximation. For sufficiently strong coupling ΓL, the impulse response features a broad delayed output pulse. In the limits of negligible and strong absorption αL, this coupling threshold reads ΓLthr=4 and Γthr=2α, respectively. The time delay and pulse height are functions of the coupling ΓL, the photorefractive time constant τ, and the effective absorption αL. Experiments on a BaTiO3 crystal measuring the absoluted square of its transfer function and the impulse response are used to determine the coupling and time constant View full abstract»

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  • A phased array optical scanning (PHAROS) device used as a 1-to-9 way switch

    Page(s): 678 - 685
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    An optical switch is demonstrated which uses a phased array of 30 closely spaced, individually addressed electrooptic AlGaAs-GaAs waveguides to focus and steer a light beam under electronic control in a planar output waveguide. A small and potentially very high speed 1-to-9 way optical switch, (with -15 dB of crosstalk) was made by placing an array of nine output waveguides at different positions in a focal plane 1 mm from the end of the electrooptic array View full abstract»

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  • Analysis of stripe multilayer waveguides with effective index and finite element methods

    Page(s): 573 - 579
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    An algorithm for a fast and accurate analysis of stripe multiple quantum well (MQW) waveguides is presented. The technique is based on the combination of effective index and finite element methods. The stripe MQW structure is replaced by an equivalent planar waveguide, using the effective index method to derive the (refractive index) profile of the planar guide from the original problem. The propagation constants and field intensity profiles of EmnX and EmnY modes for the equivalent structure are then calculated with the one-dimensional finite element method. The results obtained with this technique are presented for both symmetric and asymmetric stripe MQW structures with an arbitrary number of wells. Propagation characteristics obtained for a six-well MQW waveguide are in good agreement with those evaluated (for comparison) using full two-dimensional finite element analysis View full abstract»

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  • Characterization of ultrashort pulse formation in passively mode-locked fiber lasers

    Page(s): 720 - 728
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    Pulse formation in an all-solid-state passively mode-locked neodymium glass fiber laser is investigated by employing characterization techniques in the time, optical, and radio-frequency domains. The pulses are generated by a combination of passive amplitude modulation arising from nonlinear polarization evolution and passive frequency modulation due to quasi-soliton-like pulse shaping. Several distinct operation modes for ultrashort pulse generation are described and pulses as short as 38 fs are directly generated in the cavity View full abstract»

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  • Electroabsorption and electrooptic modulation in single crystal ZnSe-ZnSSe waveguides grown by OMVPE on GaAs

    Page(s): 663 - 669
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    Electroabsorption and the electrooptical effect were used to modulate argon laser light in ZnSe single crystal waveguides. The electrical contacts were Schottky barriers that created a nonuniform electric field in the samples. The nonuniform electric fields are modeled, and the experimental results are matched to this model. The electroabsorption experiments showed a modulation depth of 9.2 dB at an applied voltage of 255 V and a wavelength of 476 nm. With the same applied voltage at λ=488 nm the modulation depth was only 0.53 dB. Electrooptic phase modulation was also investigated. A phase shift of π was found at 60 V for a sample of 3 mm length. The half wave voltage was independent of wavelength for wavelengths from 488 to 515 nm View full abstract»

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  • Large-signal dynamic model of the DFB laser

    Page(s): 604 - 611
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    A computer model is proposed to analyze the characteristics of distributed feedback (DFB) lasers. The model is based on time-dependent coupled wave equations, with spontaneous emission taken into account. In order to avoid uncertain phase factors in spontaneous emission, a method of converting field equations to power equations in a matrix format before computation is introduced. The steady-state LI curve and transient response to the pulse excitation are calculated in the λ/4 phase-shifted DFB lasers. The longitudinal variations of the carrier and photon densities as well as of the refractive index are considered in the model View full abstract»

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  • Temperature dependence of signal gain in Er3+-doped optical fiber amplifiers

    Page(s): 640 - 649
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    Temperature-dependent signal gain characteristics at signal wavelengths of 1.536 and 1.552 μm in Er3+-doped optical fibers with a temperature range of -40 to 80°C are reported for 0.98 and 1.48 μm pumping. The temperature dependences of signal gain strongly depend on fiber length, pump wavelength, and signal wavelength. The fiber length at which signal gain temperature insensitivity occurs is found for the amplification of a 0.98-μm-pump-1.536-μm-signal, a 0.98-μm-pump-1.552-μm-signal, and a 1.48-μm-pump-1.536-μm-signal. It is confirmed theoretically that the temperature dependences result from linear changes in the fluorescence, and absorption cross sections at the signal and pump wavelengths, and a shift in the effective pump wavelength View full abstract»

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  • General expression for the efficiency of phase-matched and nonphase-matched second-order nonlinear interactions between plane waves

    Page(s): 739 - 749
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    General expressions are derived for the intensities of plane waves interacting in a second-order nonlinear process in which there are only two incident waves. The analysis covers, in a unified way, sum-frequency mixing and difference-frequency mixing and includes parametric amplification. The unified solutions are compared with several approximations in common use in order to establish regions in which such approximations can be used with reasonable accuracy View full abstract»

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  • Application of wave theory for two types of planar-diffused optical waveguide profiles

    Page(s): 658 - 662
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    Exact dispersion equations and expressions for TE-mode field distribution are obtained for two types of planar diffusion integrated optical waveguides: an Epstein asymmetrical profile and a profile consisting of a parabolic segment and an exponential part. The parabolic profile is considered as a limit case. The exact solutions are used to estimate the applicability and the accuracy of some approximate methods for analysis of planar ion-exchanged waveguides in glass View full abstract»

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  • Noise amplitude measurements of single-mode CW lasers at radio frequencies

    Page(s): 570 - 572
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    The results of noise measurements for a variety of single-longitudinal-mode CW lasers (Ar+, standing-wave-dye, and ring-dye) that are commercially available are presented. A quantitative comparison of the total output power fluctuations detected over the 7-300 MHz region (3 dB points) is presented View full abstract»

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  • The small-signal response of 1.5 μm multiple-quantum-well lasers in a two-band-model approximation

    Page(s): 624 - 634
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    The variation of the small-signal response of 1.5 μm unstrained multiple quantum-well lasers with the number of wells (NW ) is studied theoretically in a two-band-model (TB) approximation. The quasi-Fermi energies, together with gain and spontaneous emission rate spectra, are formulated analytically assuming a finite-well model and flatband conditions, including the contributions from carriers in both the wells and the barriers. The gain spectrum shows two major peaks located at the lowest heavy-hole and light-hole transitions. Therefore, the lasers under investigation are treated as three-level systems. The optical confinement factors are evaluated numerically by the matrix transfer method. The traditional rate equations are reformulated and solved for the frequency and damping rate of the relaxation oscillations in terms of an equivalent circuit View full abstract»

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  • Temperature rise at mirror facet of CW semiconductor lasers

    Page(s): 635 - 639
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    A relationship is derived for the temperature rise at the mirror facet of semiconductor lasers. The analytical result is based on the model of C.H. Henry et al. (1979) as applied to CW lasers and a thermal model. The effects of active layer length and its thickness, surface recombination velocity, output intensity, and an effective thermal length are delineated for the temperature rise. A comparison with experimental results reported in the literature shows good agreement for the facet temperature rise. A by-product is an approximate relationship for the temperature distribution along the lasing direction View full abstract»

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  • Cavity-detuning characteristics of CW additive-pulse mode-locked Nd:YLF laser

    Page(s): 700 - 709
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    Temporal and spectral characteristics of the pulses from the self-starting, additive-pulse mode-locked Nd:YLF laser using a nonlinear coupled-cavity are presented. Pulses of tunable widths are obtained over the coarse cavity-detuning range of 1 mm. Temporal shapes measured with a cross-correlation technique show that the pulses are asymmetric when the two cavity lengths are coarsely mismatched. The additive-pulse mode-locking characteristics under the fine cavity-detuning within the range of a wavelength are also investigated View full abstract»

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  • Refractive index approximations from linear perturbation theory for planar MQW waveguides

    Page(s): 650 - 657
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    The mode powers and propagation constants for planar multilayer waveguides formed with multiple quantum well (MQW) materials and with the MQW layers replaced by a single uniform layer are compared. By considering linear perturbations of the solutions of the wave equation, the optimal choice of average for the dielectric constant of the substituted single layer is determined. For the case of TE modes, minimal error in the propagation constant is predicted if a weighted average of the dielectric constants of the MQW materials is used. For the case of TM modes, using a weighted average of the reciprocal of the dielectric constants is predicted to yield the minimum error. Numerical results confirm these predictions View full abstract»

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  • Circularly symmetric distributed feedback laser: coupled mode treatment of TE vector fields

    Page(s): 612 - 623
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    The vector orientation of transverse electric (TE) fields in deriving coupled mode equations for radially outward- and inward-going modes in a circular waveguide diffraction grating is treated. The equations are derived for cylindrical waves in a system that is translationally invariant along the cylinder axis; the derivation is then extended to the waveguide geometry. The coupled mode equations are used to describe the operation of the circularly symmetric distributed feedback (DFB) laser. While predicting a similar dependence of the laser threshold gain on an azimuthal mode order to that found by a simpler, scalar-field treatment, the vector-field treatment predicts a fundamental difference in the location of the cavity resonances. The circular DFB laser is expected to lase in multiple azimuthal modes but maintain a relatively narrow overall spectral width View full abstract»

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  • Analysis of integrated optics parametric oscillators

    Page(s): 729 - 738
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    An almost analytical model for the analysis of integrated optics parametric oscillators is proposed. A comprehensive discussion of the static device characteristics of a doubly resonant oscillator with varying parameters of the optical cavity which influence the operation conditions (single and double pass and resonant pump) is presented. A detailed discussion of the evolution towards the singly resonant condition and the possibility of hysteretic behavior is also included View full abstract»

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  • Excess phase noise in self-heterodyne detection

    Page(s): 580 - 584
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    The interpretation of self-heterodyne spectra is difficult if, apart from spontaneous emission, additional noise sources are presented. Measurements on an external-cavity semiconductor laser show how, for a relatively long delay, the high-frequency (Lorentzian) wings of the self-heterodyne spectrum are a sensitive measure for the quantum-limited (Schawlow-Townes) laser linewidth. The quantum-limited laser linewidth is shown to be inversely proportional to the output power. Values below 5 kHz are routinely measured. The full width at half maximum (FWHM) laser linewidth is larger than this due to excess low-frequency fluctuations, which are shown to result from the presence of side modes 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