USA As Represented by Secretary of the Navy

Other

Purdue Research Foundation

Jason D McKinney

Keith J Williams

Vincent J Urick

John F Diehl

Andrew Marc Weiner

Mark W Beranek

Ross Schermer

Meredith N Hutchinson

Bryan Haas

Sharon R Harmon

Richard Wallway

Joseph M Singley

Jordan Hollady

Methods and apparatuses for downconverting are provided. A dual-drive mach zehnder modulator (DDMZM) receives: a continuous wavelength optical signal, an input signal (microwave signal), and local oscillator tones. The DDMZM includes: first and second arms formed from optical waveguides which receive the optical signal, a first modulator that receives the input signal, and a second modulator that receives the oscillator tones. The input signal is modulated onto the optical signal propagating through the first arm to form a first modulated optical signal. The oscillator tones and third-order intermodulation products of those tones are modulated onto the optical signal propagating through the second arm to form a second modulated optical signal. The modulated optical signals are combined to form an output optical signal. The oscillator tones are spaced two folded bandwidths apart and centered within a spectrum of interest of the input signal.

Microwave photonic links and methods of forming the same

A multicore fiber optic cable comprising of a central fiber having a central fiber outer diameter, a central fiber coating surrounding the central fiber outer diameter of the central fiber, the central fiber coating having a continuous spiraled groove around the central fiber outer diameter, a dual core optical fiber having a dual core optical fiber geometry, the dual core optical fiber spiraled around the central fiber coating and disposed within the spiraled groove such that the dual core optical fiber is wound around the central fiber coating in a spiral pattern and the central fiber core geometry and the dual core optical fiber geometry are oriented longitudinally to negate link path length difference; and an outer sheath surrounding the central fiber coating and the dual core optical fiber.

Multicore fiber optic cable

An umbrella repair assembly for reattaching a canopy of an umbrella to a rib of the umbrella includes a first shell that has a first slot integrated therein to accommodate a rib of an umbrella. A second shell is hingedly coupled to the first shell and the second shell is positionable in a closed position having the second shell abutting the first shell. The second shell has a second slot is integrated therein to accommodate the rib of an umbrella when the second shell is closed. In this way a canopy of the umbrella is compressed between the first shell and the second shell for reattaching the canopy to the rib.

Umbrella repair assembly

Systems and methods are provided for non-uniform optical sampling with wider optical bandwidth and lower timing jitter than conventional systems, which can make non-uniform optical sampling more feasible. Embodiments of the present disclosure further provide systems and methods for determining all input signal frequencies, including those left ambiguous by prior methods.

Delay-modulation-based non-uniform optical sampling and frequency disambiguation

An apparatus includes an input radio frequency waveguide. The apparatus includes a radio-frequency-to-optical-radio-frequency-impedance-matching interface communicating with the input radio frequency waveguide. The apparatus includes a plurality of optical modulators communicating with the radio-frequency-to-optical-radio-frequency-impedance-matching interface. The apparatus includes a plurality of respective optical waveguides communicating with the plurality of optical modulators. The plurality of respective optical waveguides in operation includes a plurality of respective optical waveguide fields. The input radio frequency waveguide in operation includes an input radio frequency waveguide field. The input radio frequency waveguide field interacts with the plurality of respective optical waveguide fields to convert an input radio frequency signal into a plurality of optical signals.

Multi-element optical links

In one embodiment, a roof covering system includes at least two ridge post members, a tarp at least two cables, at least two poles, at least two pole attachment members, and at least two winches. Each ridge post member may include a base configured to attach to a ridge of a roof, a head member; and a post having a bottom end and a top end, the bottom end secured to the base, and the top end secured to the head member. The tarp may have a top edge and a bottom edge, and connection points disposed near the top and bottom edges, wherein the head members are configured to attach to the connection points near the top edge. The cables may be configured to attach to the connection points near the bottom edge of the tarp. The poles may be configured to each guide a respective cable. The two pole attachment members may each be configured to attach a respective pole to a location on the roof below the ridge of the roof. The winches may each be configured to apply tension to a respective cable, thereby suspending the tarp above the roof.

Modular temporary roof covering systems

Systems and method are provided to for suppressing interference signals in optical systems, without prior knowledge of the type of location of the interferers, while maintaining a linear response to small signals of interest (SOI). By exploiting the unique power (or voltage) dependent transmission function of an externally angle-modulated photonic link, embodiments of the present disclosure are configured to provide strong, wideband interference suppression without requiring detailed knowledge of the interfering signal.

Interference suppression based on power-dependent transfer function of angle-modulated optical links

A system for measuring an RF input signal frequency includes a sampling optical pulse train with a frequency-dithered repetition-rate, and a sub-sampled analog link coupled to the optical pulse train whereby the RF input signal frequency is determined. This frequency dither imparts well-characterized modulation sidebands onto the input RF signal to be measured. By measuring the amplitude of these sidebands relative to the incoming aliased signal amplitude the frequency of the original signal is readily determined. The use of optical sampling dramatically increases the bandwidth over which the disambiguation technique is applied, and coarse disambiguation is achieved in a single acquisition.

System and method for broadband signal disambiguation based on sub-sampled analog optical links employing sample rate modulation

A system for suppressing even-order distortion in a photonic link includes a laser for providing laser light to a first input of a Mach-Zehnder modulator (MZM), where the MZM has a second input for receiving an RF input signal, a third input for applying a DC bias voltage to the MZM, and an optical signal output. A dc-voltage-biased photodiode has an input, coupled to the MZM optical signal output, and a modulated RF signal output. The MZM DC bias voltage is set at a value to generate an even-order distortion amplitude substantially equal to an even-order distortion amplitude from the photodiode and 180 degrees out of phase so as to substantially cancel the photodiode even-order distortion. The invention provides the cancellation of photodiode even-order distortion via predisortion linearization with a MZM biased slightly away from quadrature, employing a single fiber run and a single photodiode. The invention provides an improvement in carrier-to-intermodulation ratio (CIR) upwards of 40 dB.

System and method for suppression of even-order photodiode distortions

A phase-modulated analog optical link that uses parallel interferometric demodulation to mitigate the dominant intermodulation distortion present in the link. A receiver for demodulating phase modulated optical signals includes a splitter dividing the phase modulated signal into parallel optical paths, each optical path having an asymmetrical interferometer, the time delays of the interferometers being unequal, and each optical path includes a photodiode optically connected to an output of the interferometer. Outputs of the photodiodes enter a hybrid coupler. Alternatively, outputs of the interferometer enter a balanced photodetector. A phase shifter or time delay element can be included in one optical path to ensure inputs to the coupler or balanced photodetector have the correct phase. The input power to the parallel optical paths is split in a ratio that balances the third-order distortion in the output photocurrent.

Linearized phase modulated analog optical links

A photonic waveform generator and system is described. The photonic waveform generator is used in produce an electrical pulse having arbitrarily controllable temporal characteristics in a Fourier transform (FT) pulse shaper or a direct space-to-time (DST) photonic generator. The electrical pulse signal may be used in a radar, a telecommunications system or other electrical apparatus where the spectral and temporal characteristics of the signal are be optimized with respect to specific system needs, such as spectral occupancy, peak-to-average power, minimum pulse duration, target-to-clutter ratio, target type discrimination, and the like.

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Bowie, MD, United States of America

Jason D McKinney