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Quantum Electronics, IEEE Journal of

Issue 8 • Date August 1966

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Displaying Results 1 - 25 of 37
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • 1A1 - Photoelectron statistics produced by a laser operating below and above the threshold of oscillation

    Page(s): 190 - 195
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    A simple semiclassical derivation is given of the statistics of the photoelectrons emitted from a photosurface illuminated by light with statistically time dependent intensity. Comparison is made with the quantum mechanical expressions. Experiments are described that yield the probability of emission ofnphotoelectrons within a fixed time interval from a photocathode illuminated by a laser below and above threshold. The experimental results are compared with the theory developed in this paper and expressions derived by Glauber. View full abstract»

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  • 1C4 - Infrared difference frequency generation

    Page(s): 196 - 201
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    Several molecular vibrational frequencies have been generated by beating together a laser and laser-stimulated Raman emission. A Nd3+/glass laser was used to excite Raman emission from C6H6, C6D6, and CH3. NO2. The difference frequencies were generated in a single crystal of CdS and appeared at 992, 944, and 927 cm-1, respectively. A difference frequency has also been detected at 944 cm-1following mixing in CdSe. The data presented for HgS indicates that phase-matched outputs can be generated over a limited range of frequencies, provided that the Raman emission is excited with a Nd3+/glass laser. Experimental details are given and the results are discussed. View full abstract»

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  • 1C6 - Cyclotron resonance in semiconductors with far infrared laser

    Page(s): 202 - 207
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    The quantum effects in the degenerate valence bands of germanium have been observed as multiple cyclotron resonance absorption lines at a temperature of 165°K. Additional lines were resolved at 40°K. The combination of high intensity magnetic fields up to 180 000 gauss and the output power of a cyanide submillimeter laser (0.337 millimeters) was used. The construction and operation of a simple resonance spectrometer is described. Cryogenic techniques and the choice of detectors are discussed. The possible use of molecular gas laser spectrometers for EPR, ferrimagnetic resonance, and antiferromagnetic resonance at submillimeter wavelengths is considered. View full abstract»

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  • 2A4 - Analysis of room temperature CW ruby lasers

    Page(s): 208 - 214
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    Ruby lasers of between 10 mm and 75 mm length were operated continuously at room temperature in ellipsoidal pumping systems. Mode selection, relaxation oscillations, mode interaction, and thermal effects are described. CW operation was also studied with external mirrors, in 100 c/s giant pulse emission, and in single-mode emission. A ruby Pulslaser is described, that can be operated in 1 ms pulses at 50 to 120 c/s. View full abstract»

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  • 2A10 - Laser experiments for determining satellite orbits

    Page(s): 215 - 219
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    The results from a series of experiments at the Smithsonian Astrophysical Observing Station, Organ Pass, N. Mex., indicate how lasers may be used to supplement the worldwide network of Baker-Nunn cameras in obtaining precise satellite orbits for geodesy and other purposes. A pulsed ruby laser and photoelectric receiver were located at the observing station. Laser returns were obtained from the three satellites equipped with retroreflectors. The problem of aiming the laser so that its narrow beam reaches the satellite is discussed for the cases of the satellite in sunlight and in shadow. The value of the limiting range obtained experimentally is compared with that calculated from the range equation and from measurements and estimates of the background noise. Range measurements made with the laser system are compared with values determined from the orbit computations based on observations from the Baker-Nunn network. The effects of the earth's atmosphere are discussed. View full abstract»

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  • 4A3 - Intensity fluctuations in the output of laser oscillators

    Page(s): 219 - 221
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    Using population rate equations, we have calculated the intrinsic intensity fluctuations expected in the output of 3-level and 4-level CW laser oscillators. Such fluctuations stem from the quantum shot noise implicit in a restriction of the atomic and photon population-operator eigenvalues to discrete integral values (in the manner of Shimoda, Takahasi, and Townes). The intrinsic fluctuations below threshold are typical of a Gaussian distribution ofe-mfield amplitudes (Bose-Einstein distribution of photons) and above threshold of an amplitude-stabilizede-mfield (Poisson distribution of photons). The noise properties of 3-level and 4-level lasers are qualitatively similar, although for a given output power the intensity fluctuations of 3-level oscillators are greater than (or equal to) those in 4-level oscillators, principally as a consequence of the increased spontaneous emission associated with the larger upper-state occupation necessary to achieve a net gain in 3-level systems. View full abstract»

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  • 4A5 - Radiation interactions between laser oscillators with different active elements and different frequency

    Page(s): 222 - 229
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    This paper presents a novel problem in laser dynamics, where two lasers using different active material with different frequency produce radiation interaction. In the first experiment, we performed a study on the effect of radiation coupling of the giant pulse ruby laser on the Nd3+-glass laser under normal oscillation. It was found that the sudden enchancement followed by the quenching of oscillation in the Nd3+-glass makes a short, intense pulse, which was one order of magnitude or more larger than usual oscillating spikes, after the excitation by theQ-switched ruby laser light. In order to explain this result, the fluorescence study of the Nd3+-glass in the range of the visible and near infrared spectrum was arranged by employing the giant pulse ruby laser as an exciting source. This measurement has led to valuable information on the energy levels of the Nd3+-ion in the glass host through the new observation of fluorescence lines in the visible spectral region. Hence it was found that the ruby laser radiation is properly responsible for two upward transitions from the ground state in the Nd3+-glass, and thereby such radiation coupling yields the sudden enhanced emission in the laser output. View full abstract»

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  • 4B7 - Precision spectroscopy of new infrared emission system of molecular nitrogen

    Page(s): 229 - 232
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    Stimulated emission and laser oscillation resulting from transient population inversions on a number of electronic transitions of molecular nitrogen have made it possible to more accurately specify energy differences between several excited singlet states of the molecule and in one case, that of thew ^{1}Delta_{u}state, to more directly determine its absolute position with respect to the electronic ground state. Measurement accuracy has been improved on a system which we previously reported. A new emission system has been identified as resulting from transitions between thew ^{1}Delta_{u}state and thea^{1}Pi_{g}state. We have observed for the first time in the unperturbed region at lowJvalues Λ doubling inupsilon = 0ofa^{1}Pi_{g}. Very complex emission systems of more than eighty lines falling into four groups between 5.35 μm and 8.06 μm have been observed. No identification has yet been made. View full abstract»

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  • 4C5 - A zero-field maser oscillator

    Page(s): 233 - 235
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    A solid-state zero-field maser oscillator has been experimentally investigated to determine the power, stability, and spectral purity which may be expected in this type of device. The maser operates in a zero-field configuration and uses the ferric ion substituted as an impurity in an aluminum nitrate host crystal. Single-crystal and powder samples were used in the experiments, and a comparison between the sample configuration is given. View full abstract»

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  • 5B1 - Measurement of saturation induced optical nonreciprocity in a ring laser plasma

    Page(s): 235 - 243
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    When a gas laser plasma is illuminated by unequally intense laser beams traveling in opposing directions, its index of refraction becomes significantly nonreciprocal. We have studied this effect by measuring the beat frequency between the counter-rotating beams in a 6328Å He-Ne ring laser under controlled conditions. Frequency locking was effectively eliminated by using a Faraday effect beat frequency bias element. The measured beat frequency became a strong function of two independent parameters: the ring resonator tuning and the beam intensity difference. A second Faraday effect element was introduced to control non-reciprocal losses within the ring resonator. Servo loops controlling both the total laser intensity and the intensity ratio between the counterrotating beams permitted direct measurement of the non-reciprocal gain caused by saturation, or hole burning. The effects observed are contained in Aronowitz' theoretical description of ring lasers. View full abstract»

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  • 5C3 - GaAs as an electrooptic modulator at 10.6 microns

    Page(s): 243 - 245
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    The electrooptic properties of a number of semiconductors were investigated. Of particular interest was the possibility of using these materials for modulation of infrared radiation, since many of the efficient modulation materials for the shorter wavelengths, such as KTN and KDP, are opaque in this region. We have investigated experimentally the modulation potential of a number of semiconducting materials. These include ZnS and GaAs of the noncentrosymmetric 43m class. The electrooptic coefficients were determined by using a Co2, 10.6μ and a He-Ne 3.39 μ laser as the radiation source. Based on our experiments, GaAs appears as a suitable material for infrared modulation atlambda > 10mu. View full abstract»

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  • 6A2 - The influence of self-focusing on the stimulated Brillouin, Raman, and Rayleigh effects

    Page(s): 246 - 248
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    In liquids with optically anisotropic molecules the largest nonlinear polarization, cubic in the field amplitudes, corresponds to the intensity dependent index of refraction. The resulting self-focusing of the laser beam is in turn responsible for the anomalous gain of the stimulated Raman emission. The stimulated Brillouin effect in these self-focusing fluids has the same threshold condition as the stimulated Raman effect. In both cases the condition is that self-focusing occurs within the cell length. The anomalous frequency broadening in these same liquids depends on the parameter(omega_{L} - omega'_{L})tau_{c}, where ωLandomega'_{L}are two frequencies occurring in the laser beam and τcis a correlation time for molecular reorientation. In agreement with this theory, more broadening was observed at higher temperatures, although the Raman gain has the opposite trend. View full abstract»

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  • 6A7 - On self-trapping of a laser beam

    Page(s): 249 - 250
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    When a sufficiently intense light beam propagates in an isotropic medium, the latter becomes birefringent with refractive index dependent on the even powers of the electric field strength. The permittivity also increases with the refractive index. Under such conditions, at very high intensities, a new effect arises: the light beam produces a kind of dielectric waveguide embracing that part of the medium where the dielectric permittivity has undergone an increase. At sufficient power of the beam the diffracted light is totally reflected on the walls of this waveguide, and is unable to escape outwards; thus there arises a self-trapping "channel." By means of an electronic computer, data for calculating the functionD = f(P)are obtained,Dbeing the diameter of the self-trapping channel, andPthe power of the light beam entering the medium. The shape ofD = f(P)as computed numerically reveals a number of interesting features which are discussed and analyzed in detail. View full abstract»

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  • 7C7 - Infrared quantum counter action in rare earth doped fluoride lattices

    Page(s): 251 - 253
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    This paper reviews the results of a program of experimental work on infrared quantum counter action in trivalent rare earth doped CaF2, SrF2, BaF2, and LaF3lattices. The action has been found in eight of the nine possible ions that could give an output in the visible region. While the strengths of the various schemes at a 1 percent doping level are consistant with a low concentration theory, the strengths of the schemes at a 10 percent doping level indicate that there are ion-ion interactions influencing the systems. These ion-ion couplings are so effective that three photon addition schemes have been identified. View full abstract»

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  • 8B7 - Energy transfer and CW laser action in Ho3+:Er2O3

    Page(s): 253 - 255
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    Er2O3: Ho3+is an unusual laser material in that the host crystal itself provides the dominant pumping mechanism by means of energy transfer. The additional pumping bands due to Er3+and the consequent efficient transfer of energy to the Ho3+laser ion lead to relatively low threshold laser operation: 5 joules pulsed and 200W CW for a 12mm long crystal at 77°K. The emission waveleng this 2.121μ, a region of good atmospheric transmission. Additional laser experiments were carried out at 145°K. Excitation and fluorescence spectra are discussed. View full abstract»

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  • 8C1 - The laser current transformer for EHV power transmission lines

    Page(s): 255 - 259
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    A current measuring device applicable to an extra-high voltage power transmission line higher than 500 kV is proposed with preliminary experimental results. It obtains the instantaneous magnetic field ajacent to a transmission wire by measuring the angle of Faraday rotation of a laser beam in a flint glass rod. The laser beam is transmitted and analyzed at a ground potential site, and in the energized part this device has neither insulated conductors nor active elements. An experimental laser current transformer yielded a sensitivity of 66 mV per 100 A and good linearity. Various sources of error and modifications are discussed. View full abstract»

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  • 8C2 - Fluid flow measurements with a laser Doppler velocimeter

    Page(s): 260 - 266
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    The basic principles of the laser Doppler velocimeter, a new instrument for measurement of localized flow velocities in gases and liquids, are discussed in detail. Velocity measurements are made by detecting the Doppler shift in monochromatic laser light which is scattered from small contaminant particles in the fluid. ACWgas laser serves as the light source, and the Doppler shift is detected by optical heterodyne techniques. The latest fluid flow measurements obtained with the laser Doppler velocimeter are presented. View full abstract»

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  • 8C9 - Observation of cooperative effects and determination of the electron and ion temperatures in a plasma from the scattering of a ruby laser beam

    Page(s): 267 - 270
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    Observations have been made on the forward scattering of aQ-spoiled ruby laser beam from a hydrogen plasma which show clearly both the central ion peak and the satellites due to cooperative interaction between the ions and electrons. In a separate experiment on a large θ-pinch producing a high temperature deuterium plasma, the ion peak has been resolved and values obtained for both the electron and ion temperatures in the plasma. Preliminary values of the ion temperature are consistent with a thermonuclear origin for the neutron emission observed. View full abstract»

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  • 9A5 - Wide field active imaging

    Page(s): 270 - 275
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    In this paper we report the results of some experiments in active imaging-image processing in which the pictorial information is placed within the laser cavity. By the use of an active medium which provides high gain over a wide aperture, in conjunction with a highly degenerate conjugate resonator, we have been able to obtain diffraction limited resolution with an information content orders of magnitude greater than previously reported. The resonator used is the Flat-Field Conjugate Resonator (FFCR), which can support as many as 107modes of nearly equalQwhen properly designed lenses are used. As active medium we used the pulsed hollow cathode Hg+laser. In the present FFCR, two plane mirrors are imaged one upon the other by means of two achromatic doublets (focal lengths about 200 mm) located between the ends of the discharge tube and the mirrors. Active imaging is accomplished by masking one of the mirrors and observing the pattern resulting on the other mirror. Masks used include pinholes, wire meshes, and photographic transparencies as well as patterns etched in thin metallic films that were used directly as mirrors. With the doublets working nearf/10, the resolution over a 15mm diameter field was greater than 100 lines/mm, which corresponds quite well to the observed resolution of the passive system. The resonator was thus capable of actively imaging photographic transparencies having more than 106bits. One characteristic of active imaging in this type of resonator is that all the modes have a large common active volume, and the suppression of some of the modes enhances the intensity of the others. Furthermore, the nonlinear behavior of a laser as an oscillator allows sharp discrimination between differing loss levels in the cavity. These effects have been observed, and their possible application to contrast enhancement and image dissection is discussed. View full abstract»

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  • 9A9 - Pulsed laser holograms

    Page(s): 275 - 279
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    The limited coherence of most pulsed lasers is the principle difficulty in making pulsed holograms. This paper describes techniques used for the production of quality holograms of back lighted subjects, using ordinary pulsed lasers. The arrangements used achieve a temporal and spatial matching of the scene and reference beams to the degree required by the laser coherence cell. Techniques are described which prevent the destruction of the spatial match when using a diffusing screen. The use of lenses to permit the recording of large subjects on small holograms with limited pulsed energy is described. The limitations on subject motion are described. Experimental examples of the techniques are illustrated by holographic recordings of bullets in flight. The technique of double exposure holographic interferometry is also illustrated. View full abstract»

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  • 9B6 - Measurements of gain perpendicular to the junction in gallium arsenide laser structures

    Page(s): 279 - 282
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    Gain measurements are reported for radiation of wavelength 8466Å propagating in a direction perpendicular to the junction of a GaAs injection laser operated at 80°K. These results, used in conjunction with measurements of spontaneous emission, show that a gain of 2.3 percent is achieved at 7000 A/cm2. In thermal equilibrium, neglecting free carrier absorption, 0.78 percent of the transmitted radiation is absorbed in traversing the active region, 135 A/cm2being required to offset this loss. Allowance for free carrier absorption changes the above figures somewhat. The separation of the quasi-Fermi levels is also deduced from this data. View full abstract»

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  • 9B8 - Semiconductor laser amplifier

    Page(s): 283 - 289
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    The infrared GaAs injection amplifiers described have gains as high as 2000 and give output powers of 150 milliwatts when operating at 77°K and driven by a single mode. Output efficiencies of 68 percent differentiial and 50 percent overall can be obtained if the amplifier is driven by light of spectral width equal to the band-pass of the amplifier (30 Å). Regenerative effects are minimized by coating the diodes with three-fourth wavelength coatings of SiO. Thresholds at liquid nitrogen temperature were raised by a factor of ten on some diodes after the coatings were applied. Experimental data obtained on gain, efficiency, spectra, beamwidth, and noise power of several amplifiers are summarized and presented. View full abstract»

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  • 9C1 - Single transverse and longitudinal mode Q-switched ruby laser

    Page(s): 290 - 293
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    Single transverse and longitudinal modes have been observed in the output of a passiveQ-switched ruby laser when two spherical mirrors are used for the resonator. This result has been consistently obtained with several rods, with two sets of mirrors of different radius of curvature, and with a few values of reflectivity of the mirrors which proves that it is typical of a spherical resonator. The saturable absorber is a solution of vanadium phtalocyanine in nitrobenzene. To have a single transverse mode, the mirror alignment and the position of the rod within the cavity is critical. When the laser oscillates in a single mode, the output pulse is very reproducible and the fluctuations of peak amplitude and width of the pulse are less than ∼3 percent. Furthermore, as expected, the output beam has a very good spatial coherence and its divergence approaches the limits set by diffraction. As far as peak output power and width of the pulse, the best results have been obtained with one concave and one convex mirror of ∼ 5-m radius of curvature, one mirror being 99 percent and the other 50 percent reflecting. A pulse of 1 MW peak power and 30 ns half-width has been obtained. View full abstract»

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  • Post deadline abstracts

    Page(s): 294 - 298
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    Freely Available from IEEE

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