University of California

USA As Represented by Secretary of the Navy

Rehabilitation Institute of Chicago

Other

Nicola Alic

The Regents of the Unversilty of California

Stojan Radic

Ping Piu Kuo

Vahid Ataie

Nikola Alic

Daniel Esman

James R Adleman

Everett William Jacobs

Sanja Zlatanovic

Christopher K Huynh

Richard L Lieber

Ana Pejkic

Kevin Young

Yeshaiahu Fainman

George Papen

Joshua M Kvavle

Evgeny Myslivets

Nikola Alić

Andreas O J Wiberg

Camille-Sophie Bres

Andreas Olof Johan Wiberg

A system and method for ultrashort signal detection adds an optical weighting element upstream of a detector within a direct detection receiver. The optical weighting element is configured to generate an optical pulse that closely matches at least one ultrashort pulse within the input signal so that portions of the input signal that are nonoverlapping with the at least one ultrashort pulse are rejected.

System and method for receiver sensitivity improvement

A system and method for mitigating nonlinearity in an optical communication link with multiple carriers uses mutual frequency referencing to stabilize at least a portion of the multiple carriers. Using at least one frequency-referenced signal, carrier nonlinearity can be determined and compensated within the link by pre-distortion, back-propagation, or a combination of both. Mutual frequency referencing may be performed at the emitting end of the link, at the receiving end, or a combination of both.

Nonlinearity cancellation in fiber optic transmission based on frequency-mutually-referenced carriers

Methods and systems for measuring muscle sarcomere length are disclosed. In an embodiment, a method comprises illuminating a set of muscle fibers with electromagnetic radiation, measuring an intensity of the electromagnetic radiation as reflected from the muscle fibers, the measuring occurring as a function of wavelength, determining wavelengths corresponding to maximums of reflected intensity, and correlating the determined wavelengths with respective muscle sarcomere lengths. In an embodiment, a system comprises an illumination source system for illuminating the set of muscle fibers with electromagnetic radiation, and an analyzer for measuring the intensity of the electromagnetic radiation as reflected from the muscle fibers.

System for optically measuring muscle sarcomere length

A spread spectrum receiving method receives a spread spectrum signal. An optical signal frequency comb is generated. Modes of the optical signal frequency comb are modulated with a received spread spectrum signal. An optical local oscillator comb is generated that is mutually coherent with the signal frequency comb. A code word is applied to the local oscillator comb. The combs are combined and the received spread spectrum signal is detected from the combined combs.

Comb assisted spread-spectrum method

Observation of random, non-repetitive phenomena is of critical importance in astronomy, spectroscopy, biology and remote sensing. Heralded by weak signals, hidden in noise, they pose basic detection challenges. In contrast to repetitive waveforms, a single-instance signal cannot be separated from noise by averaging. The present invention demonstrates that a fast, randomly occurring event can be detected and extracted from a noisy background without conventional averaging. An isolated 80-ps pulse was received with confidence level exceeding 99%, even when accompanied by noise. The detector employed in the present invention relies on instantaneous spectral cloning and a single-step, coherent field processor. The ability to extract fast, sub-noise events is expected to increase detection sensitivity in multiple disciplines. Additionally, the new spectral-cloning receiver can potentially intercept communication signals that are presently considered secure.

Sub-noise detection of a fast random event

A spread spectrum receiver and receiving methods are provided. Received data is physically reconstructed in the optical domain using a pair of coherently coupled frequency combs, one modulated by the received signal and one modulated by the code word, and then detecting the received data with a subrate detector comprised of detector array. Particular methods and receivers extract a timing difference between the received spread spectrum signal and the codeword from the phase shifts of Fourier terms of the product of the received spread spectrum signal and the codeword that can be measured from the combined combs.

Comb assisted spread-spectrum receiver and reception methods

A photonically-assisted cyclostationary analyzer eliminates the need for high-bandwidth digitization and real-time Fourier processors by using mutually-coherent frequency combs to generate a Fourier representation of the received signal in a computation-free manner.

Comb-assisted cyclostationary analysis

Methods for optically measuring muscle sarcomere length

A receiver architecture for physically-assisted computing of transforms, such as discrete Fourier transforms (DFT) and discrete Hilbert transforms (DHT), employs mutually-coherent optical frequency combs for detection of the coherent beating between an optical signal and a reference optical tone generated by a local oscillator (LO). A signal replication mixer generates a plurality of signal optical tones having a frequency pitch with an input signal mapped thereon. A reference mixer (local oscillator) generates a plurality of reference optical tones having an offset frequency pitch relative to the signal tones. A receiver backplane detects coherent beating between the signal optical tones and the reference optical tones. The input signal may be in the optical domain or in the radio-frequency domain.

Receiver with mutually coherent optical frequency combs

A wide-band optical frequency comb is provided to estimate an optical phase shift induced in a dispersive material. In contrast to the conventional techniques that rely on a single tunable laser for extracting the dispersion parameter at different frequencies, the wide-band optical frequency comb uses multiple comb lines for simultaneously evaluating the dispersion induced phase shifts in different frequencies. Since the frequency response of the dispersive material is a phase function, a phase associated with each comb line passed through the material represents a discrete measure of the material frequency response.

Coherent dual parametric frequency comb for ultrafast chromatic dispersion measurement in an optical transmission link

An RF channelizer comprising: a master laser for generating a reference beam; a splitter for splitting the reference beam into first and second beams; first and second modulator modules for converting the first and second beams into first and second modulated beams; first and second seed tone generators for deriving first and second seed tones; first and second parametric mixers for converting the first and second seed tones into first and second combs; a signal modulator for modulating a received RF signal onto the first comb; first and second optical filters for separating the first and second combs into pluralities of first and second filtered beams with center frequencies corresponding to the second comb lines; and a coherent detection array for selecting, combining, and detecting corresponding pairs from first and second filtered beams providing at the output a contiguous bank of channelized signals covering the bandwidth of the RF signal.

RF channelizer based on parametrically generated combs derived from a single master seed

A high confinement nonlinear optical fiber is provided along with methods of parametric amplification for use thereof The nonlinear optical fiber may include a plurality of concentric layers which are configured to provide different guiding regimes to low-frequency and high-frequency components through transverse geometry and refractive index profiling, thus reducing waveguide dispersion. The resulting optical fiber provides a parametric device with phase-matching in any spectral region of interest, such that a fiber optic parametric amplifier (FOPA) implementing the optical fiber can amplify in any spectral window of interest. A narrow-band FOPA configured to minimize phase mismatching is also provided for use with the optical fiber, and may be implemented as a light source or a monochromator.

Systems and methods for fiber optic parametric amplification and nonlinear optical fiber for use therein

The present invention relates to method for spectrally equalized frequency comb generation. In order to carry this method, the following steps are followed: seed laser or lasers are modulated to acquire frequency chirp necessary to enable temporal compression and an increase in peak optical intensity necessary for an efficient nonlinear optical mixing process to occur; the compressed waveform is reshaped by nonlinear-transfer optical element and subsequently used to generate frequency comb in nonlinear waveguide. Ultimately, at the conclusion of these steps, a frequency comb is generated with substantially flat optical spectrum, while retaining variability with respect to the frequency pitch, high coherency and substantially wide spectral band of coverage.

Method for wideband spectrally equalized frequency comb generation

A method and device are provided for fast, continuous tuning of an optical source. A first pump signal with a first pump frequency is input into a mixer along with a first seed signal having a first seed frequency. Within the mixer, the first pump signal and the first seed signal generate at least one idler having an idler frequency defined as two times the pump frequency minus the seed frequency. Shifting the pump signal across a frequency range at a sweep rate causes the idler frequency to be shifted by two times the frequency range at two times the sweep rate. The shifted at least one idler is mixed with the shifted pump signal to generate a first mix product that has two times the sweep rate and frequency range of the pump signal.

Growing community of inventors

San Diego, CA, United States of America

Stojan Radic