The theory and recent applications of waves in periodic structures are reviewed. Both the Floquet and coupled waves approach are analyzed in some detail. The theoretical part of the paper includes wave propagation in unbounded and bounded active or passive periodic media, wave scatterring from periodic boundaries, source radiation (dipole, Cerenkov, transition, and Smith-Purcell) in-periodic media, and pulse transmission through a periodic slab. The applications part covers the recent development in a variety of fields: distributed feedback oscillators, filters, mode convertors, couplers, second-harmonic generators, deflectors, modulators and transducers in the fields of integrated optics and integrated surface acoustics. We also review the work on insect compound eyes, mehanical structures ocean waves, pulse compressions, temperature waves, and cholestric liquid crystals. Particles interaction with crystals is briefly reviewed, especially in the case of zeolite crystals and supelattices. Recent advances in fabrication techniques for very fine gratings me also covered. Finally, speculations about future problems and development in the field of waves in periodic structures are given.

/pdf/waves-in-active-and-passive-periodic-structures-a-review-1rmm6yq97w.pdf

Waves in active and passive periodic structures: A review

A family of novel three-terminal devices which relies on the transfer of a quasi-monoenergetic hot electron beam through a thin base is described. The devices are similar in principle to the proposed tunneling amplifier by Mead in the early sixties (“Cold Cathode” or “Metal Base” amplifiers). Results are reviewed and the probable reasons for the poor performances are pointed out. It is predicted that, with a proper choice of parameters, metal-base amplifiers can operate as switches, negative resistance devices and continuous amplifiers in the subpicosecond range. Two subclasses are described: The tunneling emitter (THETA), in the major part of the work, and the nontunneling emitter (BHETA) amplifiers. In the THETA family the metal-oxide-metal-oxide-metal (MOMOM), the MOM-semiconductor (MOMS), and the heterojunctions devices are described. Members of the BHETA family generate quasi-monoenergetic electron beams by injecting electrons by an n + n − or a metal- n − junctions, and include a variety of metals and semiconductor combinations. Very thin films are required in these devices (oxides ∼15 A, metals ∼100 A, semiconductors ∼100 A). The molecular beam epitaxy technique and lattice matching considerations are required for pinhole free semiconductors and metal films with minimum interface states. Sputter-oxidation methods are needed for thin oxide growth. Systems which combine these features with availability of microfabrication make these devices feasible today.

Tunneling hot electron transfer amplifiers (theta): Amplifiers operating up to the infrared

An optical magnetron is provided which includes a cylindrical cathode having a radius rc, and an annular-shaped anode having a radius ra and coaxially aligned with the cathode to define an anode-cathode space having a width wa=ra−rc. The optical magnetron further includes electrical contacts for applying a dc voltage between the anode and the cathode and establishing an electric field across the anode-cathode space, and at least one magnet arranged to provide a dc magnetic field within the anode-cathode space generally normal to the electric field. A plurality of resonant cavities are provided with each having an opening along a surface of the anode which defines the anode-cathode space. Electrons emitted from the cathode are influenced by the electric and magnetic fields to follow a path through the anode-cathode space and pass in close proximity to the openings of the resonant cavities to create a resonant field in the resonant cavities. The resonant cavities are each designed to resonate at a frequency having a wavelength λ, and circumference 2πra of the surface of the anode is greater than λ.

Optical magnetron for high efficiency production of optical radiation

We introduce the subwavelength transmission of an effective surface plasmon beyond the light zone via the proximity interaction of convection electrons with a metal grating. A comparative analysis of dielectric homogenization and a finite-difference--time-domain simulation shows that out-of-phase-like modes ($\ensuremath{\pi}$ modes) have strong transmission below the cutoff frequency relying on the parametric condition of structural dimension and electronic energy. The synchronous spatial field and charge distribution of the $\ensuremath{\pi}$ mode system confirms the evanescent tunneling effect of the electron-coupled plasmons.

Evanescent tunneling of an effective surface plasmon excited by convection electrons.

An optical magnetron generator is provided which includes an anode and a collector separated by an anode-collector space, a pair of output terminals operatively coupled to the anode and the collector to provide an electrical power output based on an electric field generated across the anode-collector space. The optical magnetron generator further includes one magnet arranged to provide a dc magnetic field within the anode-collector space generally normal to the electric field, and a plurality or resonant cavities each having an opening along a surface of the anode which defines the anode-collector space; an input for receiving electromagnetic radiation from an external source and operatively configured to introduce the optical radiation into the anode-cathode space to establish a resonance electromagnetic field within the resonance cavities. A cathode for introducing electrons into the anode-collector space in proximity to the resonant electromagnetic filed, wherein the resonant electromagnetic field accelerates the electrons within the anode-collector space towards the collector onto which at least one portion of the electrons are collected.

Optical magnetron generator

The interaction of an electron beam with the optical field of a periodically perturbed dielectric thin‐film waveguide is considered. When the electron velocity is nearly equal to that of one of the spatial harmonics of the field, a coherent exchange of energy can take place. This interaction, which can lead in principle to a voltage‐tunable optical oscillation, is examined in the light of presently available thin‐film techniques. An estimate of the oscillation threshold is made.

/pdf/traveling-wave-oscillations-in-the-optical-region-a-4pjopzapm3.pdf

Traveling wave oscillations in the optical region: a theoretical examination

A tunable travelling wave optical device consists of a dielectric optical waveguide with a top surface, which is periodically corrugated with a corrugation periodicity, L. At least the corrugated top surface is in an evacuated envelope wherein an electron beam with an adjustable electron velocity, ve is formed. The electron beam propagates in close proximity to and in a direction parallel to the direction of propagation of an optical beam through the guide. The electron velocity is adjusted to be greater than but on the order of the phase velocity of the first spatial harmonic generated in the corrugated waveguide. The wavelength lambda of the optical beam which is amplifiable by the device, or is produced therein when the latter acts as an oscillator, is substantially equal to c/ve L, c being the speed of light.

Travelling wave optical amplifier and oscillator

A simple pulse generator, providing continuous variation of current amplitude (0.1–35 A) and pulse width (100–700 nsec) is described. This pulser has been used for operating injection lasers at repetition rates up to 5 kHz.

Fast, high-current pulse generator with variable amplitude and width

A simple solid state circuit was used to drive GaAs injection lasers by fast (∼100 nsec) square pulses of variable amplitude (0–25 A). The amplitudes of the current pulses and the corresponding emitted light pulses were measured by a dual peak detector circuit. Using these circuits we were able to plot automatically the current vs light curve and determine the threshold current of the laser diodes.

/pdf/operating-injection-lasers-by-fast-square-current-pulses-of-3nhv9dvtf7.pdf

Operating injection lasers by fast square current pulses of variable amplitude

The circuit described is capable of generating high‐current (2–50 A), fast‐rise‐time (10 nsec), square‐wave pulses into a 50‐Ω load. This circuit may be used for driving injection lasers at high repetition rates (up to 1.5 kHz) when connected to coaxial cables.

/pdf/fast-high-current-high-repetition-rate-pulse-generator-for-4566z2awyz.pdf

Fast, high‐current, high‐repetition‐rate pulse generator for injection lasers

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