Alan D Kersey

Anthony Dandridge

Carl A Villarruel

An in-line, spectrally-selective fiber Fabry-Perot transmission filter includes an optical fiber piece having a broad-band mirror and a narrow-band Bragg grating element formed therein, the mirror and the grating forming a Fabry-Perot resonant cavity therebetween. The filter may be used to form part of a fiber ring laser configuration. The combination of the broad-band mirror and the narrow-band Bragg grating element in an optical fiber piece can also be formed into a spectrally-selective fiber Michelson filter.

Spectrally-selective fiber transmission filter system

A code-division multiplexed system comprising an optical source, a code generator for developing and applying a pseudo-random bit sequence code to the optical source to cause the optical source to develop a unipolar coded optical signal, a means for dividing the unipolar coded optical signal into N optical paths separated from each other by associated successive integer multiples of a bit period T of delay, N information signal sources responsive to the unipolar coded optical signals for selectively producing N differently-delayed optical information signals, a means for combining the N differently-delayed optical information signals into an output optical signal comprised of an intensity sum of the overlapping N differently-delayed optical unipolar information signals, a photodetector responsive to the output optical signal for developing an input electrical signal corresponding to the sum of N overlapping unipolar optical signals, an adjustable delay circuit responsive to the pseudo-random bit sequence code for producing a desired bipolar reference code corresponding to the delay associated with an associated desired one of the N differently-delayed optical information signals, and a correlation circuit responsive to the input electrical signal and to the desired bipolar reference code for synchronously correlating the desired bipolar reference code with the input electrical signal to extract a desired electrical signal corresponding to the desired one of the N differently-delayed optical information signals and to substantially suppress any other electrical signal that is asynchronously aligned with the desired bipolar reference code.

Fiber optic network system with low crosstalk using code-division

An interferometric fiber optic sensor and method are provided for controlling the optical phase of a fiber interferometer by an optically induced change in the refractive index for one arm of the fiber interferometer and providing a passive all-optical phase shift interrogation in response to this dependency on the optically induced change in the refractive index. The interferometric fiber optic sensor includes a laser source for generating light at a first predetermined wavelength, a fiber interferometer coupled to the laser source and having first and second fiber arms with a predetermined optical path difference between the fiber arms, a predetermined one of the first and second fiber arms being doped with an element for introducing an optically adjustable absorption spectrum, and a pump laser coupled to the predetermined fiber arm for generating light at a second predetermined wavelength so that an effective index for a guided mode in the predetermined fiber arm and a phase delay of the light passing through the fiber interferometer are changed. As a result, the interferometric fiber optic sensor and method allows the phase interrogation of the fiber interferometer by using a passive all-optical approach based on a pump induced refractive index change in the doped fiber arm so that balanced all fiber interferometer elements are used as sensors for eliminating laser induced phase noise.

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Fairfax Station, VA, United States of America

Alan D Kersey