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Proceedings of the IEEE

Issue 10 • Date Oct. 1966

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Displaying Results 1 - 25 of 70
  • [Front cover and table of contents]

    Page(s): c1
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    Freely Available from IEEE
  • Scanning the issue

    Page(s): 1233 - 1234
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    Freely Available from IEEE
  • [Intro. to issue on Optical Electronics]

    Page(s): 1234 - 1235
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    Freely Available from IEEE
  • Crystalline solid lasers

    Page(s): 1236 - 1248
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    A survey of crystalline solid lasers is presented. Crystalline host materials are described, pointing out their characteristics pertinent for laser systems. Rare earth and transition metal impurities operated as lasers are tabulated and the role of sensitization in increasing the overall efficiency of laser systems is described. Characteristics of operating CW lasers are given, and some applications and research directions are suggested. View full abstract»

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  • Glass lasers

    Page(s): 1249 - 1261
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    After a general discussion of the merits of glass vs. crystals as host materials for laser ions, a summary is given of the various glass lasers. Because of its importance as an efficient, room temperature laser the properties of neodymium are considered in greater detail. This includes the nonlaser properties of Nd3+in glass, the spectral and temporal emission characteristics of Nd3+lasers, and Nd3+laser configurations. Separate sections deal with the other two room temperature lasers which use Yb3+or Er3+. The problem of thermal of laser cavities is also discussed. Finally, a survey is given of the glasses that are useful as Faraday rotators. View full abstract»

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  • Gas lasers

    Page(s): 1262 - 1276
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    A review is given of the present status of gas discharge lasers, with particular attention to developments reported in 1965 and early 1966. Following a brief history, gas lasers are classified by types--neutral atom, ion, and molecular--and a comparison is given of the properties of the various types. A short discussion is given of noise and coherence properties. Detailed descriptions are given of three recent developments of particular interest--the CO2laser, the argon-ion laser, and pulsed self-terminating lasers. Finally, brief mention is made of the most important present applications of gas lasers. View full abstract»

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  • Semiconductor lasers

    Page(s): 1276 - 1290
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    This paper is a review of semiconductor laser work. The principles of operation are discussed. The stress is on work since early 1964. The present state-of-the-art in GaAs junction lasers is described. View full abstract»

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  • Pressure shifts in a stabilized single wave-length helium-neon laser

    Page(s): 1290 - 1294
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    Frequency shifts of a 6328 Å single frequency laser stabilized on the Lamp dip have been measured as a function of total helium-neon pressure and for several gas mixtures. The total shift in the pressure region between 2 and 4 torr is about 40 MHz, with a constant region between 2 and 2.5 torr. A simplified theoretical treatment is given based upon collision broadened phase shifts and line widths determined in other laser experiments. It is shown that the variations in these parameters with pressure form the basis of an adequate prediction of the observed pressure shifts. View full abstract»

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  • Computer applications of lasers

    Page(s): 1295 - 1300
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    The applicability of lasers to the logic, mentory, input-output, and data transmission linkages portions of computers are analyzed qualitatively. The more promising potential applications are considered to lie in the memory, interconnection, and input-output areas, and the least promising in the fast logic area. Coherent optical data preprocessing is cited as an example of an already clearly useful laser application. View full abstract»

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  • Optical transmission research

    Page(s): 1300 - 1311
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    The availability of coherent sources producing usable amounts of power in the optical frequency range has stimulated considerable research in optical communications. Devices such as oscillators, modulators, detectors, and ancillary apparatus having desirable characteristics exist and are being used to design and build prototype terminals. Two possible media are being studied and means are being sought to improve their performance. They are 1) through-the-atmosphere propagation and 2) enclosed media with appropriate focusing and directing elements. Experimental optical transmission systems can readily be assembled with information capacities in a single RF channel comparable to those of microwave radio or millimeter waveguide. Such optical systems are not yet competitive for high reliability common carrier service because 1) long-distance transmission techniques of adequate reliability have not yet been advanced, and 2) optical repeater components are not yet competitive with their lower frequency counterparts. Some features characteristic of optical transmission systems are reviewed in this paper, along with a brief indication of the state-of-the-art for major components. View full abstract»

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  • Laser beams and resonators

    Page(s): 1312 - 1329
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    This paper is a review of the theory of laser beams and resonators. It is meant to be tutorial in nature and useful in scope. No attempt is made to be exhaustive in the treatment. Rather, emphasis is placed on formulations and derivations which lead to basic understanding and on results which bear practical significance. View full abstract»

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  • Modes, phase shifts, and losses of flat-roof open resonators

    Page(s): 1329 - 1334
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    The integral equation of a "flat-roof resonator" is solved by the Fox and Li method of iteration in a number of particular cases. Mode patterns, phase shifts, and power losses are derived. A good overall agreement is found with the approximate theory previously developed by Toraldo di Francia. Some experimental tests carried out on a microwave model give a further confirmation of the theoretical predictions. View full abstract»

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  • High-speed photodetectors

    Page(s): 1335 - 1349
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    This paper is intended as a status report on high-speed detectors for the visible and near-infrared portion of the optical spectrum. Both vacuum and solid-state detectors are discussed, with the emphasis on those devices which can be used as direct (noncoherent) detectors of weak optical signals modulated at microwave frequencies. The best detectors for this application have internal current gain and in this regard the relevant properties and limitations of high-frequency secondary emission multiplication in vacuum tube devices and avalanche multiplication in p-n junctions are summarized. View full abstract»

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  • The antenna properties of optical heterodyne receivers

    Page(s): 1350 - 1356
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    An optical heterodyne receiver is, in effect, both a receiver and an antenna. As an antenna it has an effective aperture or capture cross section AR(Ω) for plane wave signals arriving from any direction Ω. The wavefront alignment between signal and local-oscillator (LO) beams required for effective optical heterodyning may be summarized in the "antenna theorem" ∫∫AR(Ω)dΩ = [η222where the moments of the quantum efficiency η are evaluated over the photosensitive surface. Thus, an optical heterodyne having effective aperture ARfor signals arriving within a single main antenna lobe or field of view of solid angle ΩRis limited by the constraint ARΩR≈ λ2. Optical elements placed in the signal and/or LO beam paths can vary the trade-off between ARand ΩRbut cannot change their product. It is also noted that an optical heterodyne is an insensitive detector for thermal radiation, since a thermal source filling the receiver's field of view must have a temperature T ≈ [In (1 + η)]-1hf/k to be detected with S/N ≈ 1. Optical heterodyning can be useful in practical situations, however, for detecting Doppler shifts in coherent light scattered by liquids, gases, or small particles. Another antenna theorem applicable to this problem says that in a scattering experiment the received power will be ≲ Nσλ/4π times the transmitted power, where N is the density of scatterers and σ is the total scattering cross section of a single scatterer. The equality sign is obtained only when a single aperture serves as both. transmitting and receiving aperture, or when two separate apertures are optimally focused at short range onto a common volume. View full abstract»

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  • Nonlinear optics

    Page(s): 1357 - 1374
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    Recent advances in the field of nonlinear optical phenomena are reviewed with particular empphasis placed on such topics as parametric oscillation self-focusing and trapping of laser beams, and stimulated Raman, Rayleigh, and Brillouin scattering. The optical frequency radiation is treated classically in terms of the amplitudes and phases of the electromagnetic fields. The interactions of light waves in a mterial are then formulated in terms of Maxwell's equations and the electric dipole approximation. In this method, non-linear susceptibility tensors are introdueed which relate the induced dipole moment to a power series expansion in field strengths. The tensor nature and the frequency dependence of the nonlinearity coefficients are considered. The various experimental, observations are described and interpreted in terms of this formalism. View full abstract»

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  • Electrooptic light modulators

    Page(s): 1374 - 1390
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    The field of electrooptic light modulation by means of the Pockels and Kerr effects in crystals is summarized with particular attention to communications applications using the optical maser. AH available data on electrooptic materials are tabulated, and design considerations and operating principles for various modulator configurations are outlined. View full abstract»

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  • A review of acoustooptical deflection and modulation devices

    Page(s): 1391 - 1401
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    A review of the principles of acoustooptical devices is given. Some very simple momentum conservation considerations indicate the optimum relationship between the optical and acoustic beam dimensions for various functions such as scanning or modulation. A calculation for the usual type of acoustic amplitude modulation is described, and serves as an example of the type of detailed considerations that are necessary and possible, as well as a verification of the validity of the simple momentum considerations. It is shown that the product of the fraction of the light that may be scattered and the bandwidth for Bragg scattering equals a materials constant times the acoustic power. This relationship is shown to be valid even to the extent of numerical constants for several configurations allowing a trade-off between these parameters. Thus, the required modulation power for any level of device performance is easily determined. The details of acoustic deflection under conditions of acoustic beam focusing or scanning are also given. View full abstract»

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  • Stabilization and modulation of laser oscillators by internal time-varying perturbation

    Page(s): 1401 - 1413
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    The paper reviews the application of internal time-varying perturbation to the problem of laser mode control and stabilization. The spectral characteristics and time domain behavior obtained by means of phase type and loss type perturbations are considered. Two techniques which allow the attainment of high single frequency output powers from normally multimode lasers are described. A method for the absolute frequency stabilization of an FM laser is considered, and a brief discussion of an efficient method of internal modulation, termed coupling modulation, is given. View full abstract»

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  • Carbon disulfide traveling-wave Kerr cells

    Page(s): 1414 - 1418
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    Carbon disulfide has identical microwave and optical dielectric constants, as well as extremely low optical and microwave loss. These properties make it possible to construct long traveling-wave fight modulators at microwave frequencies using the Kerr electrooptic effect induced in CS2by an electric field propagating on a TEM transmission line. Several experiments with traveling-wave Kerr cells consisting of resonant strip transmission lines immersed in CS2are described. A decrease in the microwave power required for modulation by a factor of two, by cooling the modulators to a temperature of -55°C, is demonstrated. Simultaneous modulation of light at two microwave frequencies by excitation of two of the longitudinal modes of the strip line resonator is also described. Relatively high efficiency modulation with long devices of this type is also reported. In these experiments, the microwave power required for large depths of modulation is reduced by almost two orders of magnitude compared to previously reported CS2light modulators, and is within less than a factor of two of the calculated power for cells up to 44 cm in length. For longer cells, increasingly larger than predicted powers are required. View full abstract»

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  • Digital light deflectors

    Page(s): 1419 - 1429
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    Several electrooptic digital light deflection techniques have been proposed. The maximum number of resolvable deflection positions for all methods is determined, essentially, by economic reasons, the tolerable amount of background fight, and aberrations. In this paper, three different types of deflection methods (split angle, total internal reflection, Wollaston prism) are described. Design, construction details and performance of three deflector models are reported. Combined deflection systems use the advantageous properties of each of these methods to economically obtain the maximum number of resolvable deflection positions. A suggested combination to achieve 1024 × 1024 positions arranged in a two-dimensional field would consist of one total internal reflection stage, seven stages of split angles, and two stages of Wollaston prisms for each dimension. View full abstract»

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  • A television display using acoustic deflection and modulation of coherent light

    Page(s): 1429 - 1437
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    Bragg reflection of laser light by ultrasonic waves in water produces the horizontal deflection in a television display. The ultrasonic waves are frequency-modulated with a sawtooth function. Deflection angles are small but there are 200 resolvable positions; the constant rate of angular change which characterizes a television scan permits the use of a wide optical aperture, leading to a small spot size. Conventional optical magnification follows the horizontal deflection, rendering a 3 MHz video signal visible on the screen. Bragg reflection requires the acoustic wave front to be symmetrical with respect to the incident and diffracted light rays. Thus, as the Bragg angle is altered, the acoustic wavefront should rotate. This is accomplished by a phased array of transducer strips whose combined wavefront rotates as the frequency changes, providing excellent correction over a wide band (19 to 35 MHz in this experiment, corresponding to a ±30 percent change in Bragg angle). Broadband electrical and acoustical matching techniques make it possible to diffract all the incident light with about one watt of electrical input. A second acoustic diffraction cell intensity-modulates the light. In an early experiment, the laser beam was constricted to a very small diameter before entering the modulator cell; even so, the finite beam size caused a significant loss of high-frequency response. An improved version uses an old principle (Scophony, 1939): the laser beam traversing the cell is made wide enough to encompass several picture elements, all traveling across the beam at sound velocity; the horizontal deflection system nullifies the apparent motion of these elements making them stand still on the screen while a fan of light sweeps over them. With this modulation system, spatial coherence is needed only across the vertical dimension of the laser. The tolerance on the orientation of the acoustic wavefronts, the improvement brought about by the phased array, and the amount of power needed to drive the diffraction cell are calculated and the results confirmed by measurement. there is also good agreement between the exprimentally observed optical resolution (spatial frequency response) and the theoretical expectation based on the compu- ted far-field intensity pattern. View full abstract»

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  • A survey of laser beam deflection techniques

    Page(s): 1437 - 1444
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    Methods of high-resolution, high-speed, optical beam deflection and scanning are reviewed with respect to resolution and scanning frequency capabilities. A general description is given of external deflector devices in the categories of variable reflectors, variable refractors, birefringent deflectors, and interference deflectors. The different techniques are then evaluated on the basis of their application to high-speed, high-resolution, precision scanning applications. View full abstract»

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  • A very low noise low frequency amplifier

    Page(s): 1452 - 1453
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    First Page of the Article
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  • Low-level microwave mixing in ruby

    Page(s): 1453
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    First Page of the Article
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