Geo-Centers, Inc.

Geo-Center, Inc.

Malcolm C Smith

Bruce N Nelson

An optically bidirectional electrically controlled optical switch having reduced light loss includes an electro-optic crystal having one set of fast and slow optical axes and having at least two light paths for receiving light beams through the crystal, the crystal exhibiting electric field induced birefringence such that a light beam passing through the crystal along a light path and having a plane of polarization oriented in a first direction may have its plane of polarization switched from the first direction to a plane of polarization oriented in a second direction. Beam splitting polarizers are disposed at each end of the electro-optic crystal and optically aligned with the two light paths. The beam splitting polarizers split the optical beam into two light beams having planes of polarization oriented in the first and second directions when transmitting light to the two light paths and combine the two light beams into a single light beam when receiving light beams from the two light paths. Substantially 100% of the unpolarized light input to the optical switch is transferred to the output due to the use of the beam splitting polarizers. In a preferred embodiment of the invention, the electro-optic crystal is a cubic crystal chosen from crystal classes 43 m, 42m, or 23.

Optically bidirectional fast optical switch having reduced light loss

A stress sensor having directional measurement capabilities based on the photoelastic effect in isotropic photoelastic materials. Directional measurement capability is achieved in the sensor by the incorporation of three different optical axes passing through the photoelastic element. This creates three independent stress sensors which utilize a single sensing element. Each of the three independent stress sensors are sensitive to applied stress in different directions. The response of each of the sensors is analyzed and the magnitude and direction of incoming stress is determined. The use of a sum-difference output detection scheme results in immunity to light source intensity variations, optical fiber microbending losses, and fiberoptic connector losses. The stress sensor is immune to electromagnetic interference (EMI) and electromagnetic pulse (EMP), and is compatible with fiberoptic data transmission and control lines.

Optical stress sensing system with directional measurement capabilities

A sensor utilizing a single electro-optic crystal for simultaneously measuring an electric field in three directions. By providing three light beams aligned along specific crystallographic directions and having specific polarizations, the crystal can simultaneously sense the electric field in three orthogonal directions. The crystal preferably has cubic symmetry and belongs to one of the point groups 43m or 23, such as crystals of bismuth silicon oxide or bismuth germanium oxide.

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Holliston, MA, United States of America

Malcolm C Smith