Ciena Corporation

At&t Bell Laboratories

Lucent Technologies Inc.

At+t Corp.

Semrock, Inc.

At&t Ipm Corp.

At&t Laboratories, Limited

Victor Mizrahi

Turan Erdogan

Stephen R Harmon

Robert M Atkins

Kenneth L Walker

Jean-Luc Archambault

Stephen B Alexander

Paul Joseph Lemaire

Linn F Mollenauer

Jean-Marc P Delavaux

Ligang Wang

Clinton R Giles

Henry H Yaffe

John E Sipe

Michael Y Frankel

David John DiGiovanni

Dana Zachary Anderson

Loudon Thomas Blair

John L Zyskind

Atul Pradhan

Steve W Chaddick

Kevin S Meagher

Steven W Cornelius

Donald Paul Monroe

Joseph T Foss

William M MacDonald

Renen Adar

Steffen D Koehler

Kenneth T Short

Paul A Morton

Consistent with the present disclosure, a filter is provided by depositing a coating a substrate. The coating, which may include a plurality of hard-coating layers, has an associated transmission characteristic having a passband, as well as extended blocking.

Low cost filter for fluorescence systems

An exemplary embodiment of the invention is a dispersion compensation module for compensating dispersion in a communications network. The dispersion compensation module includes dispersion compensating fiber having a dispersion coefficient that varies with wavelength. A thermal regulator adjusts the temperature of the dispersion compensating fiber to adjust the dispersion characteristic of the dispersion compensating fiber. Alternate embodiments of the invention include a communications system using the dispersion compensation module and a method for compensating dispersion.

Method and system for providing tunable dispersion compensation

A dielectric mirror including a substrate and a reflector portion disposed directly on the substrate. The reflector portion includes alternating layers, e.g. in excess of 150 alternating layers, of high and low index of refraction material. In one embodiment, the layers are configured for reflecting each wavelength in a bandwidth of 400 nm at greater than 97.5% reflectivity. In another embodiment, the layers are configured for reflecting an s-polarization and p-polarization of each wavelength in the range from 350 nm to 100 nm at greater than 98% reflectivity. High reflectivity is achieved for a wide range of angle of incidence.

Extended bandwidth mirror

An optical waveguide having a refractive index variation is formed by interfering two beams thereon and varying a fringe contrast of the interference pattern. This variation in fringe contrast may be provided by controlling the relative polarizations of the two interfering beams or the relative intensities of the two interfering beams. Preferably, a substantially constant total intensity is provided to the waveguide during the variation in fringe contrast.

Methods of writing apodized fiber gratings and associated apparatuses

A WDM ring transmission system is provided whereby each optical signal is first dropped from the ring, supplied to an amplifier, and then input to an optical receiver. Typically, a filtering element is also provided either prior to or after the amplifier. The amplifier increases the power of the transmitted optical signal so that the optical signals can be transmitted over greater distances, and the filtering element minimizes any adjacent channel cross-talk light fed to the receiver. Moreover, since the amplifier only amplifies the dropped channel, excessive noise accumulation due to non-uniform spectral gain can be avoided. In addition, channels can be arbitrarily assigned to add/drop elements along the ring.

WDM ring transmission system having amplified dropped channels

The present invention provides a wavelength division multiplexed optical communication system with dynamically stabilized wavelength selectors. To accurately correlate the wavelength of a wavelength selector to the wavelength emitted by an optical transmission source, the present invention uses an optical detector and feedback loop to optimize the wavelength of an optical selection element in accordance with a wavelength of an incident optical channel. In one embodiment, the optical selection element is a Bragg grating associated with a grating wavelength controller, such as a temperature regulator or strain tuning system, to adjust the wavelength band of maximum reflectivity of the grating. The feedback loop communicates with the optical detector and the wavelength controller to modify the grating's reflection wavelength band in accordance with the wavelength of an incident optical channel.

WDM optical communication systems with wavelength-stabilized optical selectors

An optical add/drop multiplexer (OADM) is provided wherein input optical channels are supplied on first and second optical fibers, e.g. via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups or bands of channels. Selected groups of channels to be dropped by the OADM may be demultiplexed with sub-demultiplexers into individual channels. Groups of express channels are supplied to associated filters or gratings to ensure that the channel groups selected from the first and second optical fibers to do not contain undesired channels. Channels to be added by the OADM are multiplexed with sub-multiplexers into channel groups corresponding to the dropped channel groups. The added channel groups and the express channel groups are combined on a single output fiber.

Dense WDM add/drop multiplexer

In accordance with the present invention, optical channels to be demultiplexed are supplied to first and second optical fibers via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups of channels. Each group of channels is next demultiplexed with sub-demultiplexers into individual channels, each of which is then sensed with a corresponding photodetector. Although the optical splitter introduces an optical power loss at the input to the demultiplexer, the interference filters and sub-demultiplexers create little additional loss. As a result, the total power loss associated with the present invention is significantly less than that obtained with a conventional n channel demultiplexer based on a 1&times;n splitter. Accordingly, large numbers of channels, e.g., in excess of forty can be readily demultiplexed and detected.

Dense WDM optical multiplexer and demultiplexer

A WDM ring transmission system is provided whereby each optical signal is first dropped from the ring, supplied to an amplifier, and then input to an optical receiver. Typically, a filtering element is also provided either prior to or after the amplifier. The amplifier increases the power of the transmitted optical signal so that the optical signals can be transmitted over greater distances, and the filtering element minimizes any adjacent channel cross-talk light fed to the receiver. Moreover, since the amplifier only amplifies the dropped channel, excessive noise accumulation due to non-uniform spectral gain can be avoided. In addition, channels can be arbitrarily assigned to add/drop elements along the ring. A simplified amplifier design is further disclosed.

Optical amplifier

An optical device is provided which separates one or more optical channels from a plurality of optical channels, each at a respective wavelength, and provides a length of dispersion compensating fiber for the one or more separated optical channels.

Wavelength tailored dispersion compensation apparatus

In accordance with the present invention, an optical device includes a bandsplitter for separating a wavelength division multiplexed signal into a first and second group of channels. Transmission of one or more channels within the first group of channels is suppressed by one or more filtering elements positioned within a transmission path. The one or more suppressed channels correspond to channels to be added to the wavelength division multiplexed signal. By splitting the multiplexed optical signal into separate wavelength bands, channels previously designated as add/drop channels and their associated components, do not have to be altered with the introduction of additional channels into a WDM or DWDM network. An add/drop module optically communicates with the bandsplitter to add/drop one or more of the channels included in the multiplexed optical signal.

Optical add/drop multiplexer

In accordance with the present invention, optical channels to be demultiplexed are supplied to first and second fibers via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups of channels. Each group of channels is next demultiplexed with sub-demultiplexers into individual channels, each of which is then sensed with a corresponding photodetector. Although the optical splitter introduces an optical power loss at the input to the demutiplexer, the interference filters and sub-demultiplexer create little additional loss. As a result, the total power loss associated with the present invention is significantly less than that obtained with a conventional n channel demultiplexer based on a 1&times;n splitter. Accordingly, large numbers of channels, e. g., in excess of forty can be readily demultiplexed and detected.

A WDM ring configuration having a central office node is provided in which each channel has substantially the same loss and no single channel has a disproportionately high loss. Thus, the diameter of the WDM ring in accordance with the present invention can be increased and/or the number of filters provided along the ring can be increased to accommodate additional channels.

Growing community of inventors

Columbia, MD, United States of America

Victor Mizrahi