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Quantum Electronics, IEEE Journal of

Issue 1 • Date January 1983

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Displaying Results 1 - 22 of 22
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Editorial announcement

    Page(s): 3
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    Freely Available from IEEE
  • 385 µmD2O laser linewidth measurements to -60 dB

    Page(s): 4 - 7
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    First linewidth measurements over a 60 dB dynamic range of a pulsed, high-power, optically pumped far infrared laser are presented. These measurements were made possible by using a 385 μmD2O laser with an N2O absorption filter and a sensitive heterodyne receiver. Studying a 385 μmD2O laser oscillator we find that the low-level linewidth (<-20 dB) can be explained by the ac Stark effect due to the high-power pump field. Also, we have not observed any frequency pulling of the main Raman emission frequency due to the strong pump and FIR laser fields. View full abstract»

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  • Analytical approximations for the propagation characteristics of dual-mode fibers

    Page(s): 15 - 21
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    In this paper we present accurate analytical approximations for the modal fields of dual-mode optical fibers with power law profiles based on a scalar variational analysis. We propose single parameter and two parameter trial functions and use these to study the dispersion characteristics and estimate the value of the normalized frequency corresponding to zero intermodal dispersion, which defines the operating point for such fibers. Our results show that the relatively simple single parameter field for the LP11mode gives a good fit to the field inside the core and estimates the propagation constant fairly well, but is inadequate to calculate the dispersion characteristics. On the other hand, the two parameter field estimates all these characteristics with a high degree of accuracy and enables one to accurately compute the normalized frequency for zero intermodal dispersion as well as dispersion tolerance around this value. View full abstract»

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  • AM and FM quantum noise in semiconductor lasers - Part I: Theoretical analysis

    Page(s): 34 - 46
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    AM and FM quantum noise properties of semiconductor lasers have been studied theoretically. Theoretical formulations for the AM noise spectrum, photon number probability density, FM noise spectrum, instantaneous frequency probability density, and power spectrum are presented here as functions of semiconductor laser material, structural, and pumping parameters. Two theoretical approaches are employed: one is based on the quantum mechanical Langevin equation, and the other on the density matrix equation. Starting from the quantum mechanical Langevin equation, three different formulations, that is, the rate equation, Fokker-Planck equation, and van der Pol equation, are derived. The parameters which represent stimulated emission, spontaneous emission, and refractive-index dispersion are obtained by using the Kane function interpolated to Halperin-Lax bandtail and the Stern's improved matrix element. The above four different theoretical formulations are related to each other, and the applicability for each method is discussed. View full abstract»

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  • AM and FM quantum noise in semiconductor lasers - Part II: Comparison of theoretical and experimental results for AlGaAs lasers

    Page(s): 47 - 58
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    Four different theoretical formulations for AM and FM quantum noise properties in semiconductor lasers are compared with each other for AlGaAs lasers. These formulations are based on van der Pol, Fokker-Planck, rate, and photon density matrix equations. Experimental results with AM noise spectra, FM noise spectra, and spectral linewidths for four different types of AlGaAs lasers are also delineated and compared with the theoretical predictions. The spontaneous emission coefficient β and population inversion parameter nsp, which are basic parameters for determining the quantum noise properties of semiconductor lasers, were calculated by the density of states with Kane function interpolated to Halperin-Lax bandtail and the Stern's improved matrix element. Experimental AM and FM quantum noise properties show good agreement with the theoretical predictions derived through use of estimated β and nspvalues. View full abstract»

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  • Characteristics of a photoconductive detector as an optoelectronic switch

    Page(s): 101 - 105
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    Measurements of the wavelength, signal frequency, and position sensitivities of GaAs field effect transistors used as photoconductive detectors are presented. Switching of the optical sensitivity by means of both the drain and gate voltages are demonstrated. The former method can provide the basis for employing such photoconductive detectors as optoelectronic wide-band switches. The observed properties of the field effect transistor (FET) devices studied shows that the design of photoconductive optoelectronic switches will involve compromises between sensitivity and isolation in choosing the operating wavelength, and among frequency response, power consumption, and physical size in choosing the physical layout of the device. View full abstract»

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  • Application of a variational principle to systems with radiation loss

    Page(s): 106 - 117
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    A variational principle for the frequency of electromagnetic systems with radiation is derived from Maxwell's equations. Expressions for the quality factorQare obtained in three illustrative examples: a leaky transmission line resonator, a grating coupler, and a curved slab waveguide. Extensive numerical results for theQof the grating coupler are presented in normalized form. By optimization of the variational expressions with respect to the amplitudes of the forward and backward waves, coupled-mode equations are derived for a grating structure. The variational formulas agree with results obtained from a perturbational analysis. View full abstract»

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  • Modular optical design

    Page(s): 119
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    First Page of the Article
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  • [Back cover]

    Page(s): 0
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    Freely Available from IEEE
  • Interpulse kinetics in copper and copper halide lasers

    Page(s): 88 - 91
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    The various rate processes that govern the interpulse relaxation in metal vapor and metal halide vapor lasers are considered. Computer calculations indicate that the rapid metastable levels relaxation observed in copper and copper halide laser experiments requires the existence of a relatively small resonance in the cross section for metastable excitation or deexcitation near threshold. The accurate calculation of interpulse relaxation requires knowledge of rate constants presently not well known; this is especially so for metal halide lasers. View full abstract»

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  • Laser pulse compression by stimulated Brillouin scattering in tapered waveguides

    Page(s): 7 - 14
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    The use of stimulated Brillouin scattering (SBS) for laser pulse compression by backward wave amplification in a tapered waveguide offers an attractive alternative to systems based on SRS for use with narrowband laser pulses. Almost one hundred percent conversion efficiencies may be achieved since it is not seriously limited by second Stokes production and with the added advantage that the Stokes pulse is a phase conjugate of the input pulse, under appropriate conditions. Due to the characteristically long damping times of Brillouin-active media, the SBS process is transient. In this regime, the tail of the Stokes pulse may experience a gain and loss modulation with the laser field resulting in a breakup of the Stokes pulse. This effect can be controlled by the geometric taper on the waveguide. A practical consideration of the scaling of a Brillouin compressor to high-power laser systems, notably KrF, is presented. Specific compressor configurations for the extraction of laser pulses in the nanosecond time scale are presented, and a survey of some promising compressor media indicate the practical possibility of accomplishing compression by SBS. View full abstract»

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  • Computer model of an injection laser amplifier

    Page(s): 63 - 73
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    Laser amplifiers can be used in two ways: as preamplifiers to enhance the sensitivity and improve the noise performance of detectors and, in a pulsed mode of operation, as modulators to boost and stabilize the output of an injection laser oscillator. Most mathematical models of injection lasers are based on time-dependent rate equations that ignore the spatial dependence of the electron and photon densities. The model discussed here is based on numerical solutions of traveling-wave equations. The noise output of the laser amplifier is treated by traveling-wave power equations, but the light signal is described by traveling-wave equations for its amplitude. The parameters responsible for spontaneous and stimulated emission are being related to each other by the requirement that the amplifier achieve optimal noise performance in the absence of internal losses and without gain saturation. The most important results obtained from this computer model of a laser amplifier are as follows. 1) The theory contains a heuristic electron injection efficiency parameter. To agree with experimental observations this parameter must be kept small and its value must decrease with increasing current. 2) Cavity amplifiers saturate more readily than amplifiers without feedback. 3) Because of internal loss mechanisms the amplifier supplies more noise than is required by quantum theory, but its noise performance is still surprisingly good. In particular, the optical signal-to-noise ratio prior to detection is insensitive to gain saturation by strong signals. It remains approximately 4 dB below the theoretical maximum value for weak to moderately strong input signals and drops dramatically only when the amplifier is almost completely saturated. View full abstract»

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  • Spectral tuning and linewidth narrowing of shallow-junction surface emitting GaAs LED́s through γ-ray irradiation

    Page(s): 29 - 33
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    Alterations of device characteristics as a result of γ-ray irradiation of shallow-junction surface emitting devices are different from those of deep-junction devices with respect to LED emission intensity reduction, I-V curve, line shape, and spectral shift. In particular, much larger spectral shifts in the opposite direction-toward longer wavelengths-are reported here than those found in the literature for deep-junction devices. A qualitative model based upon photochemical doping and changes in surface band bending is proposed to explain these phenomena. Changes in surface emitting shallow-junction optical radiation source device characteristics brought about by γ-ray irradiation are desirable ones for utilization in most optical fiber communication systems. These changes include linewidth narrowing, decreased time response, and decreased material dispersion because of the emission wavelength change. View full abstract»

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  • Phase-modulated optical signal detection by retardation method

    Page(s): 96 - 100
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    A noise-free signal detection technique, based on the retardation method, is described. In this method, a phase-modulated light, after being transmitted through an optical transmission line, is divided into two beams in an interferometer, and temporal correlation is made on optical phase for these light beams. The original signal is regenerated by detecting light intensity variation caused by the interference phenomenon. The light detection part structure and its optimum parameters are described. The basic retardation detection system behavior was successfully confirmed experimentally. Characteristics of the retardation method are clarified, compared to those for the heterodyne detection method. View full abstract»

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  • Optimal design of Pb1-xSnxTe double heterostructure injection lasers

    Page(s): 73 - 77
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    Results of optimization calculations are presented for broad area double heterostructure PbSnTe lasers. It was found that by adequately choosing the parameters of lasers, the threshold current densities can be substantially lowered. In particular, threshold current densities of 30 A/cm2at 77 K and of 2 kA/cm2at 200 K are predicted for devices which emit a wavelength of 10.6 μm at 77 K. View full abstract»

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  • Improved performance and rotational spectral characteristics of a doped helical TEA CO2laser

    Page(s): 82 - 87
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    In this paper, we report significant improvement in laser energy, peak power, beam quality, and arc-free operating range of pressure in a helical TEA CO2laser using a small amount of additives with low ionization potentials. The increase in laser power was found to be considerably more than the corresponding increase in laser energy with the use of additives. In addition, we observed laser oscillation on many more rotational lines including the most dominant P(20) line than is normally observed in an undoped mixture. The relative energy on the P(20) line with respect to the total energy on the rest of the lines showed a maximal behavior with pressure in the range of 0.2-1.0 atm. This has been explained using a theoretical model which takes into account reduction in both the rotational relaxation time and the rise in laser gas temperature with the increase in gas pressure. View full abstract»

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  • Lateral confinement InGaAsP superluminescent diode at 1.3 µm

    Page(s): 78 - 82
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    A superluminescent diode (SLD) has properties, based on the degree of coherence, that are bounded by those of the light emitting diode and the laser diode. The SLD can be designed to meet a wide range of optical system needs. By introducing ridge-waveguide lateral confinement, a good anti-reflection coating at one end and a high reflectivity mirror at the other, we have demonstrated an SLD that allows 30 percent coupling efficiency into a lensed 0.23 NA, 50 μm diameter graded index core fiber. The power in the fiber is 550 μW at 250 mA and 20°C. It is possible to maintain a constant power level in the fiber greater than 250 μW over the temperature range 0 to 35°C by adjusting the current. The spectral width is 300 Å and the modulation bandwidth 350 MHz. PCM with 400 Mbit/s rate has been observed. These devices are relatively easy to fabricate from ridge-waveguide lasers or any other lateral confinement laser. View full abstract»

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  • Growth of emission in a far infrared laser

    Page(s): 92 - 96
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    When the pump power is switched on, the output power of an optically pumped far infrared laser (FIR) grows up with a time delay of the order of5-50 mus and a rise time of1-10 mus in typical operating conditions. The buildup process is aperiodic at low FIR saturation and damped oscillations appear at the onset when the FIR transition is saturated. The signals in the aperiodic regime fit quantitatively very well with Lamb's semiclassical theory in the low field limit. View full abstract»

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  • The characterization and functional reliability of 45 Mbit/s optical transmitters containing MBE-grown lasers

    Page(s): 59 - 62
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    We have characterized the performance and studied the functional reliability of 45 Mbit/s lightwave transmitters containing proton-bombarded stripe lasers grown in a research environment by molecular beam epitaxy (MBE). We observe that these transmitters have superior performance compared to transmitters containing lasers of similar geometry grown in production facilities by liquid phase epitaxy (LPE), and subsequently processed using the same technology. The reliability data of over 10 000 h indicate that the functional lifetime of the MBE lasers will be limited ultimately by extinction ratio degradation in our circuit strategy. The origin of the degradation is the increase of the spontaneous light at the bias current. View full abstract»

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  • Effect of longitudinal variations in current injection and carrier concentration in laser diodes

    Page(s): 22 - 28
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    The effects of nonuniform current injection along the length of a semiconductor laser are investigated using multiple segmented stripe contact lasers. The results of the experiments are analyzed with a model for which the carrier concentration, gain, and photon density are functions of position. From the model, it was determined that nonuniform current injection caused large variations in the optical field within the laser, and the field produced a redistribution of electrical carriers in the active region. The nonlinearities in the light versus current measurements were explained by the redistribution of carriers as the optical field changed. 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