United States of America As Represented by the Secretary of the Air Force

USA As Represented by Secretary of the Navy

Other

Preetpaul S Devgan

Keith J Williams

Vincent J Urick

Nicholas G Usechak

John F Diehl

Thomas B Simpson

Joseph S Suelzer

Christopher E Sunderman

A system and method for generating optically synthesized microwave signals with broadband tunability is disclosed. The system includes a first laser and a second laser, where the first laser and second laser are optically coupled to each other. The second laser is operable to receive optical signals injected by the first laser, and to output optical signals via one or more feedback paths. The system provides for singular or mutual optical injection. A photodetector is optically coupled to the second laser over the one or more feedback paths, and operable to convert optical signals to electrical signals. A phase modulator is coupled to the photodetector, where the electrical signals from the photodetector are operable to drive the phase modulator and close the one or more feedback paths. The respective lengths of the feedback paths may be selected such that their corresponding lengths provide a frequency spacing for optical signals therein that is significantly smaller than a frequency of microwave signals.

Tunable microwave signals based on injection-locked lasers with feedback

A method and apparatus for isolating an RF signal are provided. A first RF signal is received and passed to an input of a 90 degree hybrid. An output of the 90 degree hybrid is connected to a first waveguide and a second output is connected to a second waveguide of an optical modulator. A second RF signal is received and passed to an input of a second 90 degree hybrid. An output of the second 90 degree hybrid is connected to the second waveguide and a second output is connected to the first waveguide of the optical modulator. The optical modulator is biased to produce single side band optical outputs of the RF signals. The single side band optical outputs are passed to an optical notch filter to remove one of the side band outputs. The other of the side band optical outputs is converted to an electrical signal.

Isolation of RF signals using optical single side band modulation combined with optical filtering

An apparatus is provided for RF signal discrimination. A master laser of the apparatus is connected to an optical input of an optical phase modulator. The optical phase modulator is configured to receive a plurality of RF signals at an RF input and further configured to receive an output from the master laser at an optical input. A slave laser operating below a lasing threshold is configured to receive a modulated output from the optical phase modulator. An optical filter is configured to receive a mixed signal generated inside the slave laser. A photodetector receives the filtered mixed signal and is configured to recover a RF signal from the plurality of RF signals, where a frequency of a sideband of the recovered RF signal corresponds to a mode of the slave laser.

Discrimination of low power RF signals using phase modulation with injection locked lasers

A multi-mode optoelectronic oscillator (MM-OEO) includes an OEO cavity having an input for receiving an RF signal and an RF output. The OEO cavity includes a) a first laser having a first laser output, a second laser having a second laser output, b) a modulator having i) a first input coupled to the first laser output, ii) a second input coupled to the second laser output, iii) a third input, iv) a first modulator output, and v) a second modulator output, c) a semiconductor optical amplifier (SOA) having an input coupled to the first modulator output and having an SOA amplified output, d) a photodetector coupled to the SOA amplified output and having an output, and e) a coupler having an input coupled to the photodetector output and having a first output coupled to the third modulator input and a second output, whereby an amplified RF signal is produced at the OEO RF output.

Multi-mode optoelectronic oscillator

A method and system for processing analog optical signals to produce a single RF output free from even-order harmonic distortion. Two analog optical signals of different wavelengths &#x3bb;are input into a dual-output Mach-Zehnder modulator (MZM), where one wavelength input is high-biased and one wavelength is low-biased. The complementary high- and low-biased wavelengths are output from each arm of the MZM to a multiplexer, which filters out the unwanted high- or low-biased wavelengths from each MZM arm so that both wavelengths are low-biased or high-biased. The signals are passed to a pair of photodiodes, and the photocurrents from the photodiodes are differenced to produce the final RF output. Because of the complementary phase differences between the two low- or high-biased signals generating the photocurrent, all components of the photocurrent except the fundamental and odd-order harmonics cancel each other, resulting in a high-quality RF output free from harmonic distortion.

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Dayton, OH, United States of America

Preetpaul S Devgan