Jds Fitel Inc.

Other

Fitel Inc.

Joseph W Ip

Gary S Duck

Paul Colbourne

Neil Teitelbaum

Mark Farries

Koichi Abe

Jinghui Li

Y Calvin Si

An optical element having a periodically varying spectral response is used to flatten the spectral amplitudes within each of a group of multiplexed channels having different predetermined central wavelengths with uneven spectral amplitudes peaked around the central wavelengths. Spectral equalization is achieved by having the amplitude valleys of the spectral response aligned individually with the different central wavelengths. The optical element comprises an optical cavity, which forms part of a low-finesse Fabry-Perot etalon.

Spectral equalizer for multiplexed channels

A system and method are disclosed for demulitplexing closely spaced channels carrying optically encoded data. A composite optical signal having data channels corresponding to center wavelengths .lambda.1, .lambda.2, .lambda.3, .lambda.4, . . . .lambda.n are separated into two composite optical signals of first of which comprises data channels corresponding to center wavelengths .lambda.1, .lambda.3, . . . .lambda.n and a second which comprises data channels corresponding to center wavelengths .lambda.2, .lambda.4, . . . .lambda.n-1, wherein adjacent channels center wavelengths are separated from one another by a distance 'd'. A periodic multi-cavity Fabry-Perot etalon having a free spectral range of '2d' is coupled to a circulator for launching an input beam. The first of the two composite optical signals carrying channels 1, 3, . . . n is reflected from the input port of the etalon and the second of the of the two optical signals carrying channels 2, 4, . . . n-1 is transmitted through the etalon. After the two signals are separated, further separation can be achieved by using conventional dichroic filters.

Method and circuit for demultiplexing an optical signal

An optical device simultaneously provides a multiplexing and demultiplexing function and combines dichroic WDM filter technology with Bragg grating filter technology. A plurality of adjacent sequential ports of a multi-port optical circulator serve as a vehicle for launching and receiving a multi-wavelength optical signal to be separated by the Bragg and dichroic filters. Other adjacent sequential ports having similar filters tuned to different wavelengths provide paths for combining the other wavelengths of light into a single signal. Conveniently a single circulating port serves as the input/output port of the device. The configuration can be applied an optical waveguide structure and, or more particularly to an optical fiber structure. Furthermore this configuration can combine multiplexing/demultiplexing function with a dispersion compensation function by adding a group of fiber Bragg gratings to a port of a circulator.

Hybrid bi-directional wavelength division multiplexing device

A method and device for wavelength locking is provided, wherein an element having a wavelength dependent characteristic such as a Fabry Perot etalon is used to provide an output signal having an intensity that varies with wavelength. The intensity of a reference signal derived from an input signal is compared with an output from the Fabry Perot etalon to provide a feedback signal that corresponds to the frequency of the input signal. The system is calibrated before wavelength locking is performed to determine a ratio of intensities that determines a locked state or condition.

Method and device for wavelength locking

A device in accordance with the invention uses a novel combination of two four port optical circulators, Bragg optical fiber diffraction gratings and a single erbium-doped optical amplifier (EDFA) to implement at least dual wavelength bi-directional (single fiber) optical amplifier module. A system using an amplifier module in accordance with the invention, advantageously allows communication network managers to simultaneously reduce the cost of signal amplification hardware across a fiber optic network, increase fiber utilization, simplify field installation and maintenance operations, and maintain adherence to conventional protection philosophies such as 'one system per fiber.' Furthermore, the system is tolerant of unwanted effects from back reflections that may be present from a faulty optical connector or a fiber break at either end.

Wavelength dependent crossover system for bi-directional transmission

An optical filter is provided having first and second graded index (GRIN) lenses preferably disposed in a coaxial relationship so that they have a common optical axis. Each of the GRIN lenses have an endface providing a port at predetermined location. The ports are disposed on opposite sides of the optical axis and each of the ports are substantially equidistant from the optical axis, so as to be oppositely offset from the optical axis by a same amount. The filter also includes an optical interference filter disposed between other endfaces of the first and second graded index lenses. By changing the location of the ports by a same small amount, the center wavelength of the filter changes by a small amount, thus in manufacture, the filter is tunable. After tuning the filter to a desired wavelength, the locations of the ports are fixed.

Narrow band filter and method of making same

A multi-wavelength optical filtering device for optical signal transmission, capable for functioning as a multiplexer or a demultiplexer. The device has at least one (first) optical circulator having at least four ports including an input port and a plurality of sequential ports, the last of said sequential ports being an output port, and an in-fiber Bragg grating (wavelength selective means) coupled to each of said sequential ports except said output port. The circulator may be branched off to a number of other circulators, the number depending on the number of the sequential ports of the first circulator, through the Bragg grating rather than through the output port of the first circulator. The other circulators, which are preferably also at least four-port circulators with wavelength selective means at the sequential ports, can also be branched off in an analogous manner as the first circulator. The device allows a reduction of signal losses in optical signal transmission due to the passing of a signal between circulator ports.

Multi-wavelength filtering device using optical fiber Bragg grating

A chromatic dispersion compensation device is provided in the form of an etalon having first partially reflecting mirror providing an input and output port for porting a signal into and out of the etalon cavity. A second partially reflective mirror parallel to and spaced apart from the first mirror, being more reflective than the first mirror provides a monitoring port for monitoring energy within the cavity. Means are optionally provided for controlling a parameter related to the cavity in dependence upon a signal ported from the monitoring port. Means may be provided to control a transmitting laser in dependence upon the signal ported from the monitoring port.

Chromatic dispersion compensation device

A multi-port tunable fiber-optic etalon filter (MTFET) having two spaced partially reflective mirrors, has three or more ports, with at least two on one side and at least one on the other side of the etalon. A single signal can be filtered with the reflected signal being received, forming a wavelength division multiplexor, or a plurality of signals can be filtered, with or without the reflected signals being received. A series of filters can be arranged in a cascade for sequential filtering a series of wave bands. A signal can be processed in two directions sequentially for a higher filter efficiency. A first signal can be monitored and controlled by a second signal. Various other arrangements can be provided. Integral optical processing functions can be incorporated, for example a blocking filter.

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Kanata, Canada

Joseph W Ip