Massachusetts Institute of Technology

Sycamore Networks, Inc.

Lightlab Imaging, Inc.

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

The General Hospital Corporation

Eric Arthur Swanson

James G Fujimoto

Stephen R Chinn

Murat Azizoglu

Stephen A Boppart

Mark Brezinski

Brett Eugene Bouma

Edward I McNamara

Christopher L Petersen

Richard A Barry

Guillermo J Tearney

David E Huang

Ronald B Lamport

Carmen A Puliafito

Charles P Lin

Joseph M Schmitt

Jinghui Li

Jianying Zhou

Paul A Magnin

Michael Atlas

Naimish Patel

Derek E Spock

John Zyskind

Jonathan C Bloch

Vijayanand Vusirikala

Thomas Kong

Farzana I Khatri

Joel S Schuman

Roy S Bondurant

Joseph S Schuman

Ruo Ding Li

Constantinos Pitris

Xingde Li

Marc Robidas

Gary J Tearney

David L Kelly

Optical probes having a diameter less than substantially 500 &#x3bc;m for use in scanning light from a long, highly flexible fiber to a sample. In one embodiment the probe includes a viscous damping fluid suitable to prevent non-uniform rotational distortion (NURD).

Scanning miniature optical probes with optical distortion correction and rotational control

A method and apparatus for in-circuit biasing of a modulated laser and bit error rate testing of an optical transmitter and/or optical receiver under the control of a test controller. The test controller is communicably coupled to an interface of a module under test, as well as to external test equipment. The test controller modifies operational parameters of the modulated laser, in order to obtain a desired output power and to obtain a predetermined extinction ratio. The operational parameters of the laser include a laser bias current, an electro-absorption modulator offset bias current and a modulation depth. The disclosed test controller also determines whether the optical transmitter and/or receiver exhibit acceptable bit error rates. The disclosed test controller uses a variable optical attenuator, in combination with an erbium-doped fiber amplifier (EDFA) to control an optical signal to noise ratio for a signal terminating at either the transmitter or the receiver of the optical transceiver under test. The system measures a number of relatively low bit error rates corresponding to a number of generated signal to noise ratios and, based upon the measured values, projects a signal to noise ratio for a relatively low bit error rate so as to avoid the long period of time necessary to perform actual testing to acquire bit error rate information at high optical signal to noise ratios.

Method and apparatus for in circuit biasing and testing of a modulated laser and optical receiver in a wavelength division multiplexing optical transceiver board

A fiber optic needle probe for measuring or imaging the internal structure of a specimen includes a needle defining a bore, an optical fiber substantially positioned within the bore, and a beam director in optical communication with the optical fiber. At least a portion of the wall of the needle is capable of transmitting light. The beam director directs light from the optical fiber to an internal structure being imaged and receives light from the structure through a transparent portion of the wall. An actuating device causes motion of any, or all of, the needle, optical fiber, and beam director to scan the internal structure of the specimen. The fiber optic needle probe allows imaging inside a solid tissue or organ without intraluminal insertion. When used in conjunction with an OCT imaging system, the fiber optic needle probe enables tomographic imaging of the microstructure of internal organs and tissues which were previously impossible to image in a living subject.

Fiber optic needle probes for optical coherence tomography imaging

An invention pertaining to the measurement of the freezing point of substances using OCDR and OCT.technology.

Freezing point measurement with OCDR and OCT technology

A network including a control channel source node and a plurality of control channel destination nodes is interconnected by communications media in the form of a ring. The control and control channel destination nodes transfer information over a plurality of channels using wavelength-division multiplex techniques. The control channel source node transmits control information to all of the control channel destination nodes over a unitary control channel, and each of the control channel destination nodes drains off a portion of the energy of the signal comprising the control channel to facilitate decoding and processing of the control information contained therein. Each of the aspects, the control channel destination nodes can also generate status information for transfer to the control channel source node over the control channel. The control channel source node drains off the energy of the signal comprising the control channel to facilitate decoding and processing of the status information contained therein.

System and method providing control channel for wavelength-division multiplexed network

An imaging system for performing optical coherence tomography includes an optical radiation source; a reference optical reflector; a first optical path leading to the reference optical reflector; and a second optical path coupled to an endoscopic unit. The endoscopic unit preferably includes an elongated housing defining a bore; a rotatable single mode optical fiber having a proximal end and a distal end positioned within and extending the length of the bore of the elongated housing; and an optical system coupled to the distal end of the rotatable single mode optical fiber, positioned to transmit the optical radiation from the single mode optical fiber to the structure and to transmit reflected optical radiation from the structure to the single mode optical fiber. The system further includes a beam divider dividing the optical radiation from the optical radiation source along the first optical path to the reflector and along the second optical path; and a detector positioned to receive reflected optical radiation from the reflector transmitted along the first optical path and reflected optical radiation transmitted from the structure along the second optical path. The detector generates a signal in response to the reflected optical radiation from the reference reflector and the reflected optical radiation from the structure, and a processor generating a image of the structure in response to the signal from the detector. The system provides both rotational and longitudinal scanning of an image.

Fiber optic imaging endoscope interferometer with at least one faraday rotator

An optical amplifier for a 4-fiber system having two inputs and outputs is provided that makes use of a single amplifier rather than two separate amplifiers. The optical amplifier node makes use of an interleaver before and after the single amplifier to demultiplex and multiplex even and odd channel signals traveling in opposite directions. The arrangement can also amplify wide channel spaced signals traveling through a plurality of optical fibers. The optical amplifier node can be combined with other like amplifier nodes to provide more complex amplifier solutions at reduced costs due to the need for only half of the typical number of amplifiers. The optical amplifier node can also be combined with, e.g., variable optical attenuators, L/C/S filters, channel add/drop, co- and counter-propagating Raman amplification, and dispersion compensation modules to modify the optical signals as desired.

Two fiber support with single optical amplifier

An imaging system for performing forward scanning imaging for application to therapeutic and diagnostic devises used in medical procedures. The imaging system includes forward directed optical coherence tomography (OCT), and non-retroreflected forward scanning OCT. Also interferometric imaging and ranging techniques and fluorescent, Raman, two-photon, and diffuse wave imaging can be used. The forward scanning mechanisms include a cam attached to a motor, pneumatic devices, a pivoting device, piezoelectric transducers, electrostatic driven slides for substantially transverse scanning; counter-rotating prisms, and offset lenses are used for arbitrary scanning. The imaging system of the invention is applied to hand held probes including probes integrated with surgical probes, scalpels, scissors, forceps and biopsy instruments. Hand held probes include forward scanning lasers. The imaging system is also applicable to laparoscopes and endoscopes for diagnostc and therapeutic intervention in body orifices, canals, tubes, ducts, vessels and cavities of the body. The imaging system includes application to surgical and high numerical aperture microscopes. An important application of the invention is implantation of the optical probe for periodic or continuous extraction of information from the tissue site where implanted.

Methods and apparatus for forward-directed optical scanning instruments

A Dense Wavelength Division Multiplexed (DWDM) optical transmission system that compensates for unequal channel performance over an extended fiber transmission distance. The DWDM optical transmission system includes optical transmitters at a transmitter end of a transmission path for transmitting respective channels of information at different wavelengths, a first pre-emphasis device for performing a first pre-emphasis technique on the respective channels, an optical multiplexor for combining the respective channels into a multi-wavelength optical signal for transmission on a single transmission fiber, at least one optical amplifier for amplifying the optical signal along the path, at least one second pre-emphasis device disposed along the path for performing a second pre-emphasis technique on the respective channels, an optical de-multiplexor for separating the optical signal into its component channels, and optical receivers at a receiver end of the path for receiving and detecting the information carried by the respective channels. The first and second pre-emphasis techniques performed by the respective first and second pre-emphasis devices compensate for unequal channel performance along the transmission path over a desired fiber transmission distance.

Method and apparatus for extending fiber transmission distance with multiple pre-emphases in optically amplified DWDM system

Ultra-small optical probes comprising a single-mode optical fiber and a lens which has substantially the same diameter as the optical fiber. The optical fiber and lens are positioned in a probe housing which is in the form of an insertional medical device such as a guidewire. Connector elements are provided to facilitate the attachment of the probe to an optical system and the quick disconnection of the probe from the optical system. The probe is used to obtain optical measurements in situ in the body of an organism and can be used to guide interventional procedures by a surgeon.

Ultra-small optical probes, imaging optics, and methods for using same

Data transmission apparatus includes first and second optical transmitters coupled to an optical link. A forward error correction (FEC) coder is coupled to the input of the second optical transmitter. A first information signal having a first information rate is provided to the first optical transmitter, and a second information signal having a second information rate is provided to the second optical transmitter. The use of the FEC coder enables the second information signal to have a higher information rate than the first information signal, while simultaneously enabling the respective output power levels of the first and second optical amplifiers to be substantially equal. The data transmission apparatus achieves higher data transmission capacity while retaining compatibility with pre-existing fiber spans and amplifier nodes. An optical transmission system incorporates an optical transmitter and an optical receiver having certain transmission characteristics, such as output power level, decision threshold level, etc., that are adjustable in response to bit error rate information. A bit error rate estimator is provided at the receiving end of the optical link. The bit error rate estimator estimates the bit error rate of the received information signal, and provides bit error rate information to the optical receiver, and/or the optical transmitter, and/or the optical link, based on the estimated bit error rate, in order to optimize the performance of the transmission system.

Method and apparatus for improving transmission performance over wavelength division multiplexed optical communication links using forward error correction coding

Multiple gigabit Ethernet (GbE) and Fiber Channel (FC) signals are multiplexed and transported on a wavelength-division multiplexed (WDM) communications link using synchronous optical network (SONET) signaling. A transmitter decodes the 8b/10b encoded GbE/FC signals to reduce their respective signaling rates to no greater than the payload data rate of an OC- signal used on the link. The decoded signal are packetized into fixed-size packets in order to append a stream identifier used for de-multiplexing at the receive end. The packetized streams are multiplexed together and formatted into the OC- signal, which is transmitted over the communications link. A receiver de-multiplexes the received signal to obtain the packet streams, converts the packet streams to the corresponding decoded signals, and re-encodes each signal to re-create the original GbE/FC signals. A pair of interfaces can be arranged to provide independent adding or dropping of the GbE/FC signals that share the same wavelength.

Method and apparatus for transporting gigabit ethernet and fiber channel signals in wavelength-division multiplexed systems

An apparatus for measuring the optical-signal-to-noise ratio (OSNR) of an optical system is adapted to function in single channel or in multi-channel wavelength division multiplexed optical communication systems. An optical signal spectrum and a center frequency characterize the optical signals. A narrow-band notch filter, realized by an in-fiber Bragg grating, is utilized to remove a component of the signal so the remaining signal can be measured. When multiple channels are present, a bandpass filter is used to select the part of the multiplexed signal to be measured. Both the narrow-band notch filter and the bandpass filter can be tunable to further extend the capabilities of the system. Two detectors are utilized with the power in the channel being measured by a low-gain detector and the power in the noise being measured by a high-gain detector. A processor receives the detector outputs, calculates OSNR, and controls the tunable components.

High resolution optical performance monitor for DWDM system

An imaging system wherein an optical signal is transmitted to both a sample to be measured and a rotating element which is calibrated to the system. A return signal is detected by the system, and a scan analyzer and correction unit uses the system calibration information along with synchronization information to correct for return signal degradation or errors due to imperfections in the rotating element in real time. This allows for an accurate measurement of the sample. The system can also include a coarse path-length adjustment unit to allow the system to track a region of interest within a sample to further allow for accurate sample measurement.

Methods and apparatus for high speed longitudinal scanning in imaging systems

Method of performing OFDR on a sample comprising steps of: providing an external-cavity frequency-tuned laser having an optical cavity of effective length; tuning the laser to generate a change in wavelength; changing the effective length of the optical cavity proportionally to the change in wavelength so as to tune the longitudinal cavity mode frequency at the same rate as the wavelength is changed; directing light from the laser onto the sample; receiving light reflected from the sample; combining light reflected from the sample with light from the external-cavity frequency-tuned laser; detecting the combined light and generating a beat signal in response thereto; and performing digital signal processing to extract spatial information about the sample in response to the detected beat signal. An OFDR system is also disclosed comprising: a laser comprising an output port; an optical ring having a round trip time, a center frequency and a broad-bandwidth gain medium; a wavelength selecting device in optical communication with the gain medium; a frequency shifter in optical communication with the gain medium and the wavelength selecting device; and an optical coupler in optical communication with the optical gain medium, the wavelength selecting device, and the frequency shifter. The optical coupler couples light from the optical ring to the output port, wherein the wavelength selecting device tunes the center wavelength at a rate equal to the incremental change in frequency caused by the frequency shifter divided by the round trip time of the optical ring thereby providing nearly continuous frequency sweep.

Growing community of inventors

Acton, MA, United States of America

Eric Arthur Swanson