Abstract: A design theory is described for rectangular waveguide metal insert filters that includes both higher order mode interaction and finite thickness of the inserts. Optimized design data for three- to five-resonator type filters with severaf insert thicknesses suitable for metal stamping and etching techniques are given for midband frequencies of about 15, 33, 63, and 75 GHz. Measured passband insertion losses of prototypes for mid-band frequencies of 15, 33, and 76 GHz are 0.2, 0.6, and 0.7 dB, respectively.

Abstract: We have grown multilayer samples of a polydiacetylene upon a metallized grating forming a planar waveguide structure. By measuring the change with optical intensity in the coupling angle between an input laser beam and a planar waveguide mode in the structure we estimate the intensity‐dependent index of refraction, n2≂10−6 (MW/cm2)−1 (λ>7500 A), for the polydiacetylene. Also, a large resonant enhancement of the optical nonlinearity was observed.

Abstract: Diffused channel-waveguide couplers were fabricated on z-cut y-propagating LiNbO3 crystals by the indiffusion of titanium. Both mode spot sizes and coupling lengths were measured. The fields and coupling lengths were computed for both TM and TE polarizations from fabrication conditions. Good agreement was obtained between the measured and computed mode spot sizes and coupling lengths. It is concluded that the calculation method could aid in the design of such couplers.

Abstract: Nonlinear coupled waveguide is studied for optical pulse compression, utilizing the power‐dependent performance of such waveguides caused by the intensity‐dependent refractive index in the region of interaction. Theoretical calculations predict that the pulse compression to less than 1/5 of the original pulse width is achievable with a loss of 3 dB.

Abstract: A three-dimensional finite-element scheme is proposed for finding directly the electric or magnetic field at a given frequency of excitation inside a closed system containing lossy inhomogeneous materials of arbitrary shape. It is shown that the scheme may be used to find the scattering parameters of general two-port linear waveguide problems. Results are presented for four cases.

Abstract: A light source (10) coupled to a first fiber optic waveguide (14) which is coupled by a first directional coupler (22) and a second directional coupler (24) to a second waveguide (20). The first waveguide (14) has a phase modulator (60), a delay loop (62) and a polarization controller (68) therein to cause a differential delay time T on counterpropagating coherent light waves phase modulated at a frequency 1 M . The first directional coupler (22) has one part connected to a photodector (28) and the second directional coupler (24) has a probe (20D) coupled to the first fiber (14) and the second fiber (20). The probe directs light toward a surface (18) whereupon the counterpropagating waves are shifted in phase by an amount proportional to the amplitude of displacement of the surface 18.

Abstract: We describe the design and preliminary performance characteristics of a compact sealed, transverse rf discharge excited waveguide CO2 laser which is capable of output powers of 30 W and a peak efficiency of 13% from a 37‐cm discharge length.

Abstract: This paper describes the influence of fabrication parameters on fiber-Ti:LiNbO 3 waveguide-fiber insertion loss measured at \lambda = 1.32 \mu m in c -cut LiNbO 3 . We present a systematic study of the influence of titanium thickness on insertion loss. Within the range examined, diffusion of 950 A thick 6 μm wide strip of Ti at 1050°C for 6 h produced the minimum loss of 2.0 dB in a 2 cm long waveguide for both TE and TM modes. An analysis of fiber-waveguide coupling for the particular case of an asymmetric diffused waveguide is presented. In general, we find that coupling loss due to modal mismatch between the fiber and waveguide and propagation loss in the waveguide contribute approximately equally to total insertion loss.

Abstract: An array (48, 49, 50, 51) of fiber optic couplers coupling an input (45) and an output (46) waveguide The output waveguide (46) is routed among the couplers of the array such that either backward or forward coupling exists With backward coupling, energy coupled into the output waveguide (46) in a coupler of the array is guided back to the preceding coupler for coupling back into the input waveguide (45) The backward coupling allows recirculations to occur between couplers to create poles and zeroes in the transfer function of the array which transfer function can be programmed or tailored somewhat to have specific characteristics Further, the backward coupling allows the array to be used for matrix-vector multiplication

Abstract: An optical interferometer matrix which includes a reference waveguide (10) for optically transmitting a reference signal. The optical interferometer matrix further includes a signal source waveguide (12) for optically transmitting a source signal which has been modulated with respect to the reference signal in response to an applied physical effect. The physical effect may be, for example, thermal, acoustic, hydrodynamic, electrical, electro-mechanical or magnetic. The reference and signal waveguides (10, 12) are then optically coupled to one another at two different points (38, 40) so that interference between the light in the waveguides occurs under two different phase conditions, with a phase difference between these conditions which approaches pi/2 radians. In the preferred embodiment, the two points of optical coupling are confined in a small space so that thermal- or pressure-induced differential phase changes of light between the first and second coupling points (38, 40) are negligable.

Abstract: The nonradiative dielectric waveguide (NRD-guide) is a newly proposed dielectric waveguide which can substantially suppress radiation at curved sections and discontinuities and is applicable to great advantage for millimeter wave integrated circuits. Basic circuit components such as transitions between a metal waveguide and an NRD-guide, matched terminations, a ring resonator and a bandpass filter were fabricated with polystyrene material and tested successfully at 50 GHz. Measurements showed that each component worked as expected without suffering from undesirable radiation and interferences at all.

Abstract: An optical channel waveguide is manufactured by forming an optical isolation pedestal or ridge on a substrate and coating the substrate and pedestal with an optical channel layer. The optical channel waveguide is that portion of the optical channel layer which overlies the pedestal. Cladding layers may be added overlying the optical channel film or the cladding function may be performed by air. The disclosed process requires no high temperature diffusion steps and is thus suitable for manufacturing optical channel waveguides integrated on a semiconductor substrate with semiconductor devices. In addition, the entire process for manufacturing the optical channel waveguide may be carried out during a single pumpdown of a vacuum system.

Abstract: A device for distributing and combining microwave electric power which is used, for example, in a high power microwave amplifier and combines or distributes microwave electric power between a first microwave path such as a standard waveguide and a plurality of second microwave paths such as a plurality of waveguides or MIC transmission lines. The device comprises a horn whose throat portion is coupled to the first microwave path, a oversized waveguide coupled to the opening portion of the horn at one end and coupled to the plurality of the second microwave paths, and, for example, a dielectric lens, or one or more reflectors, for uniformalizing the phases of the microwave signals distributed by the horn or for adjusting the phases of the microwave signals output from the second microwave paths.

Abstract: Measurements are described on Z-LiNbO 3 , single-mode, channel waveguide directional couplers for the TE- and TM-mode polarizations at 0.83- and 1.3-μm wavelengths. The coupling characteristics for each polarization are strongly dependent on the mode confinement, and, hence, on the mode dispersion, and also vary differently with changes in mode dispersion. With particular waveguide fabrication parameters, the TE- and TM-mode coupling coefficients are equal for any waveguide spacing; for other fabrication conditions, the coupling coefficients are always unequal or equal at only one spacing. Theoretical calculations, based on experimentally determined diffusion parameters, follow the trend of measured values in most cases and correctly predict the effect on the coupling characteristics of changes in waveguide fabrication.

Abstract: The longitudinal variation in the voltage across a waveguide channel, excited by a transverse radio‐frequency discharge has been analyzed in terms of simple transmission line theory. It is shown that the voltage variation follows a cosine curve for the waveguide structure in the absence of a discharge, and that this behavior is only slightly modified when a discharge is running. The voltage may exhibit variations of 30% for cases where the relevant waveguide length is only one tenth of the effective rf wavelength. However, it is shown that this variation may be reduced to below 5%, by the use of multiple feed points or by appropriate inductive termination of the line. Experimental results are in good agreement with theoretical predictions.

Abstract: The dispersive properties of a relativistic electron beam in a dielectric‐loaded waveguide are investigated. The linearized fluid and Maxwell’s equations are used to derive the dispersion relation and to study the eigenmodes for the system. The Cerenkov microwave radiation mechanism is investigated.

Abstract: A method of heating objects by microwave energy by supplying microwave energy from a generator to a first waveguide. A second waveguide is located, separated from the first waveguide except for at least one parallel and adjacent coupling distance at a common wall between the waveguides. A coupling of microwave energy distributed in the wave propogation direction of the waveguides takes place at the coupling distance so that microwave energy passes from one waveguide to the other one. The second waveguide is dimensioned, so that action of load (objects being heated) conducts microwave energy in the second waveguide with the same wave phase constant as the first waveguide. Objects to be heated are fed only into and out of said second waveguide. A uniform field is fed-in only into the first waveguide. A uniform field distribution and heating profile is obtained and leakage of microwave energy from the open ended second waveguide is avoided.

Abstract: Experimental and analytical results show single longitudinal mode operation of groove-coupled two-section GaInAsP/InP lasers during the initial turn-on transient. Optical outputs remain single mode (spurious down ≥10 dB) for temperature ranges \sim \pm3\deg C. Laser thresholds and internal current densities are comparable to conventional devices without grooves. Analytical results characterizing the grooves, the below threshold coupled-resonator mode selection, and the complete dynamical buildup of laser energy are summarized. Waveguide scattering theory forms the basis for much of the analysis.

Abstract: A useful quantity in the description of junction circulators is the difference between the split frequencies of the magnetized ferrite resonator. A knowledge of this quantity allows the loaded Q-factor of a junction using a weakly magnetized resonator to be determined. This paper derives an exact description of the former quantity in the case of the open quarter-wave long (partial-height) disk resonator used in the construction of commercial turnstile waveguide circulators. This is done by employing duality between a ferrite-filled circular waveguide having ideal electric wall boundary conditions and one having ideal magnetic wall boundaries. The effect of an image wall on the open flat face of the open resonator is considered separately. The paper includes some remarks about the susceptance slope parameters of disk and triangular open resonators.

Abstract: Dispersion properties of the electromagnetic (EM) waves, propagating through a tape helix located inside a waveguide, are investigated. A complete dispersion relation for the eigenfrequency omega and the axial wavenumber kappa is obtained, including influence of the outer conducting wall on the EM-wave propagation. It is shown that the fimiting case where the outer conducting wall is very close to the helix, the helix mode is nearly a straight line in the (omega, kappa) parameter space, and is independent of the width of the helix tape. Moreover, contrary to the conventional helix theory, the outer conducting wall completely eliminates the forbidden regions in the (omega, kappa) parameter space.

Abstract: An RF-discharge waveguide laser having two parallel waveguides is improved by the addition of coupling channels which permit the plasma in said waveguides to communicate

Abstract: A general, linear theory of coupling electromagnetic fields from free-space waveguide arrays to an inhomogeneous plasma in a magnetic field is presented. In contrast to previous analyses, which assumed parallel-plate waveguides, waveguides having closed cross-sections of arbitrary shape are considered; full account is taken of all the waveguide modes. Far away from the coupling region, the plasma is assumed to be absorptive and the waveguides to propagate only their dominant modes. The formulation is geared to obtain the reflection coefficients in the waveguides and the excitation of waves in the plasma. The results are applicable to RF heating of plasmas whose size is large compared to the waveguide array, as would be the case in a fusion reactor, and valid for the frequency regimes of either ion-cyclotron (harmonic), or lower-hybrid, or electron-cyclotron (harmonic) heating.

Abstract: A new electro‐optic analog‐to‐digital converter that makes use of an array of channel waveguide Fabry–Perot modulators is reported. Since this converter utilizes only straight channel waveguides, it should possess the inherent advantages of small substrate size, simple geometrical layout, and low optical insertion loss. Experimental results obtained with a four‐bit converter in a X‐cut LiNbO3 substrate have demonstrated some of these desirable features.

Abstract: A method is presented for approximating the impedance or admittance properties of arbitrarily large but finite dielectric covered phased arrays which use a plane wave expansion of the fields radiated by the elements The method is general in its application to dipole, slot, or waveguide geometries even though results from dipoles near resonance are used in this paper Results calculated using the method are compared to a well-established procedure for an array in free space Further results for a dipole array in a dielectric slab are presented, and a problem which occurs due to a surface wave phenomenon is dealt with in an approximate manner using the insights possible from the physical interpretations of the method The method is also shown to be valuable in its predictions of edge effects and behavior of impedances across the extent of large finite arrays which methods that work with infinite arrays or small finite arrays cannot accomplish

Abstract: A waveguide connection formed between a rectangular waveguide (11) and an elliptical waveguide (12) having a cutoff frequency and impedance different from those of the rectangular waveguide (11) comprises an inhomogeneous stepped transformer (10) having multiple sections (31,32,33) all having inside dimensions small enough to cutoff the first excitable higher order mode in a pre-selected frequency band, each section (31,32,33) of the transformer having an elongated transverse cross section which is symmetrical about mutually perpendicular transverse axes (X,Y) which are common to those of the waveguides (11,12), the dimensions of the said cross section increasing progressively from step to step in all four quadrants along the length of the transformer in the direction of both transverse axes (X,Y) so that both the cutoff frequency and the impedance of the transformer (10) vary monotonically along the length of the transformer (10).

Abstract: A light source (10) coupled to a first fiber optic waveguide (14) which is coupled by a first directional coupler (22) and a second directional coupler (24) to a second waveguide (20). The first waveguide (14) has a phase modulator (60), a delay loop (62) and a polarization controller (68) therein to cause a differential delay time T on counterpropagating coherent light waves phase modulated at a frequency 1 M . The first directional coupler (22) has one part connected to a photodector (28) and the second directional coupler (24) has a probe (20D) coupled to the first fiber (14) and the second fiber (20). The probe directs light toward a surface (18) whereupon the counterpropagating waves are shifted in phase by an amount proportional to the amplitude of displacement of the surface 18.