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Quantum Electronics, IEEE Journal of

Issue 10 • Date October 1977

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Displaying Results 1 - 19 of 19
  • [Front cover and table of contents]

    Page(s): 0
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  • Wavelength dependence of gain saturation in GaAs lasers

    Page(s): 848 - 854
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    The amplification of light in GaAs lasers is calculated self-consistently. It is shown that the wavelength dependence of the gain saturation is caused by the change of the chemical potential within the excited region due to the coupling of the carrier density with the photon density via the stimulated emission process. The effect of the wavelength dependent gain saturation on the stimulated emission spectra is calculated and compared with experimental results. Comparison of different recombination models indicates that a band-to-band transition withoutk-selection rules including tail states is the most appropriate description of the experimental data even for pure material. View full abstract»

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  • A 16-µm radiation source utilizing four-wave mixing in cooled parahydrogen gas

    Page(s): 871 - 875
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    Improvements in a 16-μm radiation source based upon the combined effects of stimulated rotational Raman scattering and resonantly enhanced four-wave mixing in parahydrogen gas are described. For this source, the input waves of which are provided by temporally and spatially coincident pulsed beams from a ruby and CO2TEA laser, it was found that cooling the parahydrogen gas from 300 K to <100 K, at constant molecular density, increased the output at 16 μm by roughly a factor 4. The maximum output was measured to besim 40 muJ/pulse, which is near the theoretical limit for the 2.5 MW CO2laser intensities that were applied. View full abstract»

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  • [Back cover]

    Page(s): 0
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  • Composite one- and two-pass gain saturation in the geometric mode limit of unstable resonators

    Page(s): 803 - 805
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    Design curves, of the geometric mode limit output power of gain-saturated confocal positive branch unstable resonators with mirror separation large compared to mirror diameters, are given as a function of mode magnification, ratio of mean cavity to small signal gain coefficients, and axial and transverse distributions of the small signal gain coefficient. View full abstract»

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  • Observation of new FIR superradiant lines from optically pumped D2O

    Page(s): 811 - 812
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    Four new laser lines from optically pumped D2O vapor are reported at wavelengths of 235 μm, 280 μm, 97 μm, and 98 μm, the latter having a quantum conversion efficiency of 38 percent. View full abstract»

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  • Discharge stabilization in HF lasers using resistive electrodes

    Page(s): 801 - 803
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    The use of a resistive (50-Ω. cm resistivity germanium) cathode in an SF6-C3H8chemical HF laser is described. Specific outputs of 4 to 5 J/l can be obtained at relatively modest capacitor charging voltages without preionization or the use of especially low inductance circuitry. View full abstract»

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  • Optically pumped GaAs lasers with two-dimensional Bragg reflectors

    Page(s): 806 - 807
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    We report experiments on oscillations of a new two-dimensional distributed-feedback (DFB) laser. A pair of distributed Bragg reflectors (DBR) and another perpendicular corrugation were formed on a GaAs crystal and the sample was optically pumped at 77 K. We observed oscillation of a two-dimensional mode in addition to that of a one-dimensional mode. View full abstract»

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  • Mode coupling in optical waveguide horns

    Page(s): 828 - 835
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    Mode coupling in optical waveguide horns is described in detail. Analytic approximations for the coupling constant and phase difference are derived. For a parabolic-shaped horn an expression for the power transferred out of the lowest order mode is obtained, which demonstrates that long structures will be needed to maintain adiabatic operation. View full abstract»

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  • Theory of optical-waveguide distributed feedback lasers: A Green's functions approach

    Page(s): 843 - 848
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    The total scattered electric field of a periodic dielectric optical waveguide is derived in terms of the Green's functions of the unperturbed structure. A condition for self-excitation that takes into account the coupling between radiation and guided modes is obtained in a very general manner and, therefore, is valid for arbitrary periods of the grating structure. Results show that the effect of the coupling between the oscillating guided field and radiation modes is to change the dependence of the threshold gain on the amplitude of the periodic perturbation: increasing the depth of the grating beyond an optimum value causes an increase in threshold due to larger coupling to radiation modes. View full abstract»

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  • CW ruby laser pumped by an argon ion laser

    Page(s): 808 - 809
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    A simple CW ruby laser pumped by a 514.5-nm argon ion laser, utilizing an uncoated ruby rod (no external mirrors), is described. The output does not exhibit spiking, but does show a low amplitude ∼1 percent) of modulation. View full abstract»

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  • Transverse mode control in high gain, millimeter bore, waveguide lasers

    Page(s): 813 - 819
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    A technique is presented for assuring TEM00transverse mode operation in visible wavelength lasers with bore diameters of 0.1- 1.0 mm. This then is a solution to the problem of obtaining TEM00mode output from pulse pumped dye lasers which have high and non-uniform gain. The desired mode control is achieved by confining the lasing medium in a waveguide and placing each resonator mirror so that its focal plane, rather than its center of curvature, lies at the nearest waveguide opening. Thus, the far-field pattern of the field distribution emerging from the waveguide opening is focused by the mirror back into the waveguide. For the proper choice of mirror curvature, the width of the central lobe of the far-field pattern is such that over 99 percent of the energy couples into the two lowest order modes of the waveguide. The waveguide transmits this bell-shaped field distribution to the opposite end where the process of propagating to the mirror and being reimaged is repeated. The end result is that a pulsed, laser pumped, waveguide dye laser has been made to produce a mode of the same quality as a TEM00mode, CW, HeNe laser. This technique has also improved the output mode distribution of flashlamp pumped dye lasers. Analysis of the resonator shows that a TEM00mode having a curved wavefront at the waveguide opening couples primarily to both the EH11and EH12waveguide modes. The amplitudes of the EH11and EH12modes, however, have a complex phase difference which results in a refocusing of the field distribution when both propagate in a hollow waveguide. The refocusing is shown to be a periodic function of the length of the waveguide. In addition, it is shown that as a result of gain or propagation loss differences for the two waveguide modes, the phase radius of curvature of the TEM00mode of a waveguide resonator does not in general match the mirror curvatures. This model of TEM00mode coupling to the EH11plus EH12modes results in a clearer physical insight into the interaction between the waveguide and free space portions of the resonator. View full abstract»

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  • Spectral properties of pulsed dye lasers

    Page(s): 855 - 865
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    The model of a homogeneously broadened laser with pulsed excitation is considered. We compute solutions of coupled non-linear differential rate equations describing the spectral properties of the emission as a function of time. It is shown that the use of appropriately space averaged quantities allows one to take into account gain saturation effects. Injected, Fabry-Perot etalon tuned and broad-band oscillator emissions are studied. Spectro-temporal evolution of the laser emission which occurs in all cases is the main result of the computations and fully supports, as expected, the previously derived analytical equations. In addition it is shown that the basic phenomenon of spectral evolution implies the existence of an "ultimate wavelength" of the emission. How to predict the optimum and limits of injection locking is discussed in terms of a "delocking time." View full abstract»

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  • Detection of laser pulse asymmetry by three-photon fluorescence

    Page(s): 875 - 880
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    It is shown that the well known loss of asymmetry information in single time delay (STD), three-photon fluorescence (3PF) measurements of short laser pulses can be recovered by splitting the main beam into two parts with distinctly nonequal intensities before recombining them in the fluorescent media. A mathematical formulation is presented which relates the ability to recover asymmetry information with the loss of contrast brought about by the use of nonequal intensities, where both depend upon the temporal position along the pulse. The characteristics of the asymmetry detectability are affected by the degree of mode locking of the laser pulse. A numerical simulation confirms the results. View full abstract»

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  • Fluorescence and oscillation characteristics of LiNdP4O12lasers at 1.317 µm

    Page(s): 836 - 842
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    Spectroscopic data and laser oscillation characteristics of the 1.317 μ line in lithium neodymium tetraphosphate (LNP) are reported. A stimulated emission cross section of this transition was spectroscopically determined as7.1 times 10^{-20}cm2, which corresponds to 1/4.5 of that at the 1.047-μm transition. Cross-section temperature dependence, laser cavity loss, threshold versus crystal length, and threshold temperature dependence were measured experimentally. Since resonant loss was negligible at the 1.317 μm line, room temperature threshold is lower than that at 1.047-μm in the case of long crystal, and threshold temperature dependence is weaker than that at 1.047 μm. A miniaturized LNP laser, using a graded index fiber as a focusing medium, is also shown. LED pump intensity required to obtain a constant output is compared for 1.047- and 1.317-μm wavelengths. The 1.317-μm line seems to be useful as miniaturized optical sources in optical communication systems, since required intensity is around several W/cm2for the side pump, and the wavelength corresponds to the most transparent band of ultra low-loss optical fibers. View full abstract»

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  • LED fundamentals: Comparison of front- and edge-emitting diodes

    Page(s): 819 - 827
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    We establish a criterion for the maximum amount of power that can be launched into an optical fiber relative to a front-emitting diode of given active layer (junction) thickness. According to this criterion it should be possible to obtain 7.5 times the amount of power from a light-emitting diode (LED) of optimum design relative to a front-emitting LED whose active layer of equal intrinsic brightness is 2.5 μm thick. We also discuss the performance of edge-emitting diodes and find that the LED's of our examples are capable of providing approximately 50 percent of the power expected from the ultimate diode configuration. View full abstract»

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  • Frequency-locking of a CW dye laser to the center of the sodium D lines by a Faraday filter

    Page(s): 866 - 871
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    Single-mode CW oscillations at the center of the sodiumDlines have been achieved by inserting a Faraday filter in an argon-laser-pumped dye laser cavity. The oscillations at the D1and D2lines can be selected by choosing adequate values of the sodium temperature and the magnetic field strength. Experimentally obtained conditions to get the single-mode oscillations at the center of theDlines are compared with the theoretically calculated feature of the Faraday filter, and a relatively good agreement has been found. The shifts of oscillation frequencies due to the magnetic field are also discussed. 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