University of Kansas

Nortel Networks Corporation

Sprint Communications Comapny L.p.

Northern Telecom Limited

Ciena Corporation

University of Texas System

Bookham Technology Limited

Rongqing Hui

Maurice M O'Sullivan

Christopher Thomas Allen

Maurice Stephen O'Sullivan

Trenton Shuey

Alan Robinson

Junfeng Jiang

Douglas Lew Richards

Stephen Arthur Oliva

Andrea Fumagalli

Ross Alexander Saunders

Jin Hong

Toshi Makino

Guo P Li

Ken Demarest

Chris Allen

Kenneth Robert Demarest

Jin J Hong

Peter Adany

Dietmar Garthe

Jingyu Zhou

Hong-Xing Jiang

Chris Johnson

Jing-Yu Lin

Benyuan Zhu

A transmitter generates a first electrical signal comprising a first low-frequency signal, an empty period, and a pump pulse having a first frequency; and a second electrical signal comprising a second low-frequency signal and at least two probe pulses, each probe pulse having a second frequency that differs from the first frequency. The transmitter modulates first and second optical subcarriers having different polarizations using the first and second electrical signals, respectively. The transmitter generates an optical signal from the first and second optical subcarriers, wherein the first and second low-frequency signals overlap in time, wherein the empty period overlaps in time with one of the probe pulses, and wherein the pump pulse overlaps in time with another one of the probe pulses. The optical signal is detected at a receiver over an optical link, and the receiver uses the optical signal to estimate nonlinear phase shift in the optical link.

Estimating nonlinear phase shift in a multi-span fiber-optic link using a coherent receiver

The present invention uses digital subcarrier cross-connect switching to accomplish various network processes more efficiently. These processes include interconnecting network components, and performing optical and optoelectronic add/drop operations.

Digital subcarrier cross-connect switching

A low-altitude altimeter () and a method of determining low altitudes for unmanned aerial vehicles (). The altimeter includes at least two illuminators (), at least one sensor (), and a computing device (). The illuminators () emit signals which are received by the sensor () in such a way that an angle at which they are received is determinable by the computing device (). The computing device () processes each signal received by the sensor (), determines the angle at which the sensor () received the signal, and, based thereon, determines the altitude of the unmanned aerial vehicle (). When a first pair of illuminators are arranged along a fuselage axis, and a second pair of illuminators are arranged orthogonally to that axis, the computing device can combine first and second altitude, pitch angle, and roll angle measurements to provide a more refined altitude determination.

Low-altitude altimeter and method

A method is provided for measuring polarization dependent loss in an optical transmission system. In the method, a first optical signal is generated, and a polarization of the first optical signal is altered over time. The first optical signal is combined with a second optical signal from the optical transmission system to yield a combined optical signal, which is coherently detected to yield a radio frequency signal. A power of the radio frequency signal is measured. The measured power of the radio frequency signal is processed to generate an indication of the polarization dependent loss of the optical transmission system.

Measurement of polarization dependent loss in an optical transmission system

An optical homodyne detection scheme for FM chirped lidar is described. The system performs de-chirping within a photodetector, and it does not require high-speed photo-detection or RF mixing. Embodiments are also described for dealing with phase noise.

Coherent detection scheme for FM chirped laser radar

The present disclosure relates to the use of III-nitride wide bandgap semiconductor materials for optical communications. In one embodiment, an optical device includes an optical waveguide device fabricated using a III-nitride semiconductor material. The III-nitride semiconductor material provides for an electrically controllable refractive index. The optical waveguide device provides for high speed optical communications in an infrared wavelength region. In one embodiment, an optical amplifier is provided using optical coatings at the facet ends of a waveguide formed of erbium-doped III-nitride semiconductor materials.

Method and apparatus for use of III-nitride wide bandgap semiconductors in optical communications

A receiver system processes a received optical signal that carries user information. The receiver system includes a splitter, a first converter, a second converter, and a detection system. The splitter splits the received optical signal based on polarization into a first optical signal and a second optical signal. The first converter converts the first optical signal into a corresponding first electrical signal. The second converter also converts the second optical signal into a corresponding second electrical signal. The detection system applies radio frequency detection to the first electrical signal to generate a third electrical signal. The detection system applies radio frequency detection to the second electrical signal to generate a fourth electrical signal. The detection system then combines the third electrical signal and the fourth electrical signal to form a fifth electrical signal that carries the user information.

Optical systems with diversity detection

An Optical Domain Signal Analyzer, having an optical filter, a dispersive element and a detector is utilized to provide high resolution spectrum analysis over a wide optical bandwidth. The optical domain signal analyzer broadly includes an optical filter for providing wavelength samples of a received optical signal, a dispersive element for receiving the samples and dispersing the samples, and a detector for receiving the dispersed signal and for providing electrical signals representative of the dispersed sample. A preferred embodiment includes a processor for receiving the electrical signal and calculating the characteristics of the spectrum.

Optical domain signal analyzer

The present invention provides a method and apparatus for monitoring optical signals with an expanded frequency resolution. The invention permits high-resolution measurements of optical signal spectrums while retaining wide bandwidth operation through appropriate control circuitry. An interferometer having a periodic frequency response formed of equally spaced narrow-band peaks is used to sweep the entire signal spectrum. The interferometer frequency response is incrementally tuned in cycles so that each of its frequency response peaks cyclically scans a particular spectral band of the signal spectrum. During each cycle, the interferometer isolates multiple spectrally resolved portions of the optical signal spectrum where each portion originates from a different spectral band. In this way, a high-resolution measurement of the entire signal spectrum can be obtained. The invention may be network protocol independent and can be incorporated into an optical spectrum analyzer or directly into any optical terminal. The invention can be used for signal spectrum monitoring applications including link quality monitoring (LQM) in optical communications networks to monitor various transmission parameters such as such as carrier wavelengths, optical signal-to-noise ratios (SNR), amplified spontaneous emissions (ASE), noise levels, optical non-linearities or other signal baseband information such as data rates and formats.

Method and apparatus for high resolution monitoring of optical signals

A compact source capable of generating continuously tunable high frequency microwave radiation and short optical pulses in the picosecond/sub-picosecond range is invented. It includes a laser structure having two lasers formed on the same substrate which simultaneously operate at different longitudinal modes. Each laser has a complex coupled (gain-coupled or loss-coupled) grating which is formed by deep etching through a multi-quantum well structure, either of the active medium or of the additional lossy quantum-well layers, thus ensuring no substantial interaction between lasers. The lasers have a common active medium and shared optical path and provide mutual light injection into each other which results in generation of a beat signal at a difference frequency of two lasers. The beat frequency is defined by spacing between the laser modes and may be continuously tuned by current injection and/or temperature variation. Thus, the beat signal provides a continuously tunable microwave radiation. To form a train of short optical pulses, the beat signal is either further sent to a saturable absorber followed by a semiconductor optical amplifier, or sent directly into an optical compressor which includes a dispersion fiber. As a result, a duration of each impulse is compressed, and a train of short optical pulses is formed.

Generation of short optical pulses using strongly complex coupled DFB lasers

A clock recovery system recovers an optical clock signal from an optical data signal that is wavelength and data rate independent. The system splits the optical data signal into a first optical data signal and a second optical data signal. The system then transmits the first optical data signal and the second optical data signal in opposite directions around a fiber loop. In the fiber loop, the system modulates and amplifies the first optical data signal to generate a modulated-amplified first optical data signal. The system then recovers the optical clock signal after the modulated-amplified first optical data signal and the second optical data signal interact in the fiber loop.

Method and apparatus for recovering an optical clock signal

The present invention provides a method and apparatus for monitoring optical signals with an expand frequency resolution. The invention permits high-resolution measurements of optical signal spectrums while retaining wide bandwidth operation through appropriate control circuitry. An interferometer having a periodic frequency response formed of equally spaced narrow-band peaks is used to sweep the entire signal spectrum. The interferometer frequency response is incrementally tuned in cycles so that each of its frequency response peaks cyclically scans a particular spectral band of the signal spectrum. During each cycle, the interferometer isolates multiple,spectrally resolved portions of the optical signal spectrum where each portion originates frog different spectral band. In this way, a high-resolution measurement of the entire signal spectrum can be obtained. The invention may be network protocol independent and can be incorporated into an optical spectrum analyzer or directly into any optical terminal. The invention can be used for signal spectrum monitoring applications including link quality monitoring (LQM) in optical communications networks to monitor various transmission parameters such as such as carrier wavelengths, optical signal-to-noise ratios (SNR), amplified spontaneous emissions (ASE), noise levels, optical non-linearities or other signal baseband information such as data rates and formats.

A device for encoding data into high speed optical train includes N data encoding branches, each having a dual-mode laser, generating at the beat frequency f, and an external modulator. Each dual mode laser includes a laser structure having two sections formed on the same substrate which simultaneously operate at different longitudinal modes. Each section has a complex coupled (gain-coupled or loss-coupled) grating which is formed by deep etching through the multi-quantum well structure, ensuring no substantial interaction between lasers. The sections have common active medium and shared optical path and provide mutual light injection into each other. Signals from the branches are put through a variable delay line, introducing phase shifts between the signals, and compressed in the optical compressor. Thus, N short pulse optical trains are formed. The phase shifts between the signals are adjusted so that, when the trains are further combined in the optical combiner, they interleave in a precise timing to form one combined optical pulse train of frequency Nf. Thus, encoding of data at a speed, which is much higher than the speed of the external modulator, is achieved. The corresponding method of encoding data is also provided.

Growing community of inventors

Lenexa, KS, United States of America

Rongqing Hui