Purdue Research Foundation

US Government As Represented by the Secretary of the Army

Neal C Gallagher

Kevin John Webb

Tanveer U Haq

Joseph P Fitch

Charles R Christensen

Steven C Bass

Edward J Coyle

Ronald G Harber

A mode control device for operation at a selected wavelength in cooperation with first and second waveguides, integrates first and second adjacent layers for passing electromagnetic energy from the first waveguide to the second waveguide through the layers in series. In a first embodiment, the first and second layers are composed of materials having a distinct indices of refraction and are spaced apart a distance other than one-quarter of said selected wavelength. In a second embodiment, the layers are disks having distinct circular diameters.

Compact waveguide mode control and converter devices

A method for designing an aperiodic grating structure for mode conversion and control which is based upon an inverse scattering optimization procedure. In accordance with this method, no predetermined shape or material variation of the grating structure is assumed. A constrained domain of all surfaces and material variations is searched to find an optimum aperiodic conversion surface profile for maximum conversion efficiency into the required output mode(s) or optimum control. Accordingly, the present method results in the design of rough surfaces or non-homogeneous structures for mode conversion and control. Because this method relies on scattering produced by short, forceful field perturbations, it is possible to achieve very small conversion lengths which are much less than one grating period. For microwave frequencies this method can be used to design mode converters, mode filters, frequency filters, phase shifters, mode launchers, waveguide transitions and adapters, power splitters, phase shifters, couplers, etc. Optical applications of this method include and are not limited to the design of waveguide transitions and couplers, mode converters, aperiodic gratings, aperiodic Bragg reflectors, narrowband filters, holographic elements, etc. In all these cases the propagation medium may be a waveguide of any shape, material and size, or it could be free space. Efficiencies close to the theoretical maximums are obtainable with this method.

Design method for compact waveguide mode control and converter devices

A method and apparatus of digitally filtering an M-level signal decomposes the M-level signal into M-1 binary threshold signals by thresholding it at each value from 1 to M-1. The kth threshold signal has the value 1 at a given position if and only if the input signal is at least k at that position; otherwise it has the value 0. Filtering each of the M

Digital filtering by threshold decomposition

A beamrider guidance system for missiles wherein a laser beam is given two circular motions around the boresight axis to produce amplitude and phase modulation on the signal received at the missile. The information on distance from boresight is contained in the amplitude modulation and the angular information is contained as phase modulation. A laser optical system with a spinning holographic element provides one of the circular motions for the beam. The other circular motion is provided by a low frequency, circular scanning mirror.

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West Lafayette, IN, United States of America

Neal C Gallagher