Rockwell International Corporation

Trw Limited

US Government As Represented by the Secretary of the Army

Harris Corporation

Shi-Kay Yao

Charles K Asawa

Michael K Barnoski

Rudolf R August

Dean B Anderson

Richard A Gudmundsen

David E Thompson

Joseph W Austin

Stewart D Personick

Cecil L Hayes

Michael J McNutt

Eddie Hung Young, Jr

John D Anderson

Jack E Soohoo

Allan R Jackson

Joseph W Niesen

Apparatus and a corresponding method for launching two light beams into an optical fiber as two separate modal groups, and for separating light emanating from a fiber into two modal groups. The apparatus includes first and second lenses and a spatial modal filter in the form of a reflective disc disposed coaxially between the two lenses. When the apparatus is used as a launching device, the first lens operates to collimate light from a source of light modulated by a data signal and intended for launching as lower-order modes. The lower-order-mode light is reflected from the filter and focused by the first lens into an output fiber. The second lens collimates light from a source of light indicative of a monitor signal to be transmitted in the form of higher-order modes. This light is partially blocked by the spatial modal filter, then focused into the output fiber by the first lens. The fiber constrains this light to enter the output fiber at angles of incidence greater than some predetermined threshold angle. When the apparatus is used as a modal separator, the first lens collimates light from an input fiber, and the modal filter reflects only the light corresponding to the lower-order modes, allowing the higher-order modes to pass into the second lens and be focused into an output fiber. The reflected lower-order modes are focused by the first lens into another output fiber.

Device and method for modal separation and combination in an optical

An acoustical phased array having improved interaction efficiency and efficiency-bandwidth product. The array includes a body of acousto-optical material having one face grooved to form a number of sets of plane parallel surfaces, each set having n different height levels, where n is at least two. An electro-acoustic transducer is affixed to each surface and high-frequency signals are applied to the respective sets of transducers, each signal being phase-displaced by the same amount with respect to the signal applied to an adjacent set. The incremental height difference is 1/n of the phase difference between signals applied to adjacent sets, expressed in wavelengths, and this results in elimination of one lobe of what would otherwise be a twin-lobe far-field acoustic radiation pattern, and an approximate doubling in interaction efficiency.

Phased-array acousto-optic Bragg cell

A low loss optical waveguide is provided by taking a silicon substrate with a silicon dioxide waveguide thereon and depositing lead on the air interface surface of the silicon dioxide. The lead is then oxidized and diffused into the silicon dioxide creating a high optical quality, high index region at the air interface of the waveguide. This allows transmitted waveguide light energy directed into the silicon dioxide to be transmitted in the lead oxide diffused portion of the waveguide, keeping the energy away from the lossy silicon substrate, and thereby providing a low loss planar waveguide.

Low loss, single-mode planar waveguide

A system for remote measurement of structural forces includes a plurality of microbend transducers mounted along the length of the structure for microbending an optical fiber in response to structural forces, such as stress acting upon an oil or gas pipeline or the like. An optical time domain reflectometer (OTDR) has a light source for launching a pulsed optical signal for passage through the fiber and a photodetector for sensing as a function of time the intensity of backscattered light reflected back through the fiber, wherein this sensed time function is correlated directly with discrete longitudinal positions along the length of the fiber and the structure. When one or more of the microbend transducers is activated to induce a microbend in the fiber in response to localized forces acting upon the structure, a portion of the backscattered light is lost at the microbend. This attenuation in backscattered light intensity is sensed quantitatively and positionally identified by the photodetector. Specific preferred constructions for microbend transducers and system arrangements particularly adapted for detecting structural strain in an oil or gas pipeline are disclosed.

Microbending of optical fibers for remote force measurement

A system for remote measurement of structural forces includes a plurality of microbend transducers mounted along the length of the structure for microbending an optical fiber in response to structural forces, such as stress acting upon an oil or gas pipeline or the like. An optical time domain reflectometer (OTDR) has a light source for launching a pulsed optical signal for passage through the fiber and a photodetector for sensing as a function of time the intensity of backscattered light reflected back through the fiber, wherein this sensed time function is correlated directly with discrete longitudinal positions along the length of the fiber and the structure. When one or more of the microband transducers is activated to induce a microbend in the fiber in response to localized forces acting upon the structure, a portion of the backscattered light is lost at the microbend. This attenuation in backscattered light intensity is sensed quantitatively and positionally identified by the photodetector. Specific preferred constructions for microbend transducers and system arrangements particularly adapted for detecting structural strain in an oil or gas pipeline are disclosed.

An optical system including a radio frequency signal input; a chirp signal input; a source for emitting a beam of radiation; an acousto-optical modulator disposed in the path of the beam and functioning to modulate the beam with the radio frequency signal and the chirp signal to produce a modulated beam; and a single detector disposed in the path of the third modulated beam. The inventor further provides electronic alignment and focusing by changing the chirp frequency.

Self scanned optical Fourier transform arrangement

An optical system for performing a cosine transform on an input RF signal is described. The optical system includes a source for emitting a beam of radiation, and an acoustic-optical modulation device disposed in the path of the beam and functioning to modulate at least two spaced-apart spatial portions of the beam with different signals to produce two modulated beams. A Fourier transfer lens is provided which is disposed in the path of the two modulated beams for combining the two beams, and a detector is disposed in the path of the Fourier transform beam at the focal plane of the Fourier transfer lens.

Optical cosine transform system

An acoustic wave device wherein each electrode element of an interdigital transducer is buried or embedded between a pair of layers of piezoelectric material. The use of a multi-layer stack of layers of piezoelectric material enables each electrode element of the transducer to be sandwiched between a distinct pair of layers and thus to be insulated from the other electrode element or elements. Because of the insulation thus provided, the spacing between the fingers of each electrode element may be selected without fear of causing short circuits between electrode elements.

Surface acoustic wave device having buried transducer

An optical system including a radio frequency signal input; a chirp signal input; a source for emitting a beam of radiation; a first acousto-optical modulator disposed in the path of the beam and functioning to modulate the beam with the radio frequency signal to produce a first modulated beam; a second acousto-optical modulator disposed in the path of the first modulated beam to modulate the beam with the chirp signal to produce a third modulated beam; and a single detector disposed in the path of the third modulated beam.

Optical signal processing device

A CCD driven integrated optical modulator array including an array of chirp grating optical lenses implemented on the surface of an electro-optical crystal such as LiNbO.sub.3 or LiTaO.sub.3, a plurality of channel waveguides and a thin metal film pattern on the surface of the waveguides for modulating the optical waveform in each channel. The thin metal film form planar capacitors, each of the capacitors being electrically connected to the output circuit of a corresponding semiconductor device, such as a CCD array. The CCD array is implemented on a semiconductor wafer bonded to the electro-optical crystal. Signals in each optical channel in the electro-optical crystal are thereby modulated by corresponding circuit elements associated with corresponding CCD channels implemented on the major surface of the semiconductor wafer.

CCD Driven integrated optical modulator array

A Sagnac interferometer gyroscope includes a semiconductor chip on which is formed an optical waveguide. Means are provided on the optical waveguide to inject a laser light beam into the waveguide and onto a divider to produce first and second divided beams. Second and third dividers are provided in the waveguide to generate a reference signal onto a pair of photodectors disposed to receive the divided light waves. The light waves are modulated with first and second frequencies prior to their second division by a pair of Bragg frequency shifter interdigital transducers. The divided and modulated light beams are then directed through an optical path encompassing an axis of sensitivity of the gyro. In one embodiment the path is formed by an optical fiber with connections to the chip. In another embodiment the optical path is defined within the chip itself by reflectors or deflectors at selected locations about the peripheral of the chip. The respective light beams after having traversed the light path are then combined and detected by a second pair of photodectors. The signals of the photodectors are compared to determine the rotation of the gyroscope about the axis of sensitivity.

Interferometer gyroscope formed on a single plane optical waveguide

A high-throughput diffraction-limited Bragg diffraction grating having a variable periodicity functions as a lens for optical guided waves. The lens may be fabricated with planar photolithograhic techniques. It has predictable focusing properties which are insensitive to process variations making it particularly useful for mass production of integrated optical systems.

Chirp-grating lens for guided-wave optics

A digital-to-analog optical recorder incorporating both CCD and integrated optics technologies which is fabricated as a single integral unit including an electro-optical layer portion and a semiconductor layer portion. Sampling circuits and digital-to-analog converters are implemented on the semiconductor layer portion using CCD technology, and a plurality of optical channel waveguides and electro-optical modulators are implemented on the electro-optical layer portion. Each digital signal is converted into two complementary light spots at the output of the recorder.

Growing community of inventors

Anaheim, CA, United States of America

Shi-Kay Yao