Coolerless pump wavelength optimization for Er/Yb-doped optical fiber amplifiers
Granted: July 31, 2003
Application Number:
20030142395
An optical fiber amplifier has a pump module operating at a shorter wavelength at room temperature than conventional optical fiber amplifiers. At the maximum operating case temperature, the output from the pump module is still at a lower wavelength than the upper absorption band edge of the optical fiber. In a further embodiment, an Er—Yb co-doped optical fiber is further doped with aluminum to flatten a portion of the optical absorption profile. Co-doping with aluminum reduces the…
Integrated optical splitter
Granted: July 17, 2003
Application Number:
20030133663
The invention relates to an integrated waveguide optical tap coupler, which includes an input waveguide, a tapered section, and a pair of output waveguides. The upper edges of the tapered section and one of the output waveguides defines an arc of a circle with a first radius, while the lower edges of the tapered section and the other output waveguide defines an arc of a circle with a second radius. The proximate ends of the two output waveguides are separated by a truncated wedge tip…
Method for increasing dynamic range of erbium doped fiber amplifiers
Granted: July 10, 2003
Application Number:
20030128420
The present application relates to a doped fiber amplifier having an increased dynamic range, and particularly for laser pump sources and a method of pumping erbium doped fiber amplifiers over a greater dynamic range. In a multi-channel optical system, optical amplifiers must be able to provide gain over a larger range of signal powers, the dynamic range corresponding to the number of channels in the link. The present invention has found that the dynamic range of an EDFA can be…
Athermal optical coupler
Granted: July 10, 2003
Application Number:
20030128932
The invention relates to an optical coupling device that provides passive compensation for a shift in center wavelength due to a change in ambient temperature. A conventional solution is to mount one of the elements to be coupled on a pedestal or cantilevered arm, which has a coefficient of thermal expansion (CTE) different from a frame fixed relative to the other of the elements to be coupled. Unfortunately, these devices do not provide consistent results over long periods of time, due…
Wavelength interleaving add/drop multiplexer
Granted: July 10, 2003
Application Number:
20030128986
The invention relates to an add/drop multiplexer utilizing at least two stages of wavelength interleaver technology to provide high isolation, while dropping and adding subsets of periodically spaced wavelength channels. The primary function is to separate a first subset of periodically spaced wavelength channels, e.g. even ITU channels, from an input signal, and then to combine the remaining channels, e.g. odd ITU channels, with another subset of channels having the same center…
Optical performance monitoring device
Granted: July 3, 2003
Application Number:
20030123119
Optical performance monitoring device for monitoring and analyzing an optical signal has a periodically movable reflective mirror to receive an input optical beam and to cyclically “scan” (deflect) the beam in a one-dimensional direction. The deflected beam at a varying deflection angle is directed to a linear variable filter (LVF) that passes a selected wavelength channel of the deflected beam in dependence upon the deflection angle. The selected channel is then passed to a…
Doped absorption for enhanced responsivity for high speed photodiodes
Granted: June 19, 2003
Application Number:
20030111675
A photodiode with a semiconductor intrinsic light absorption layer has at least one p-doped light absorption layer or an n-doped light absorption layer, and preferably both. The diode also has a cathode electrode and an anode electrode electrically couple with the p-doped light absorption layer or the n-doped light absorption layer.
Wavelength blocker
Granted: June 12, 2003
Application Number:
20030108284
A wavelength blocker including an input port for launching an input beam of light, first dispersing means for dispersing the input beam of light according to wavelength, an array of independently addressable elements for selectively blocking a portion of the dispersed beam of light, second dispersing means for receiving the passed dispersed beam of light and for producing a single multiplexed beam of light therefrom, and an output port for transmitting a modified output beam of light.…
Fiber-coupled optical attenuator
Granted: June 12, 2003
Application Number:
20030108324
An optical attenuator has a planar MEMS substrate supporting two optical fibers; an actuator; and a silicon vane actuatable by said actuator for a movement into and out of the optical beam passed between the fibers. The vane is configured to divert at least a portion of the optical beam off the optical axis when the element is moved into the optical beam. The vane has at least one surface disposed non-perpendicularly relative to the optical axis of the beam. The vane may be of a wedged…
Optical fiber for resisting hydrogen-induced loss
Granted: May 29, 2003
Application Number:
20030099455
The invention provides an optical fiber composition which has a high resistance to aging upon exposure to hydrogen. The inventive optical fiber does not require further treatment steps, such as passivation or hermetic coating, to meet specifications for hydrogen aging. The inventive optical fiber has a core glass composition with a germania doping concentration from 0% to 4% in weight. Decreasing the dopant concentration of germanium increases the resistance of the fiber to hydrogen by…
Truncated series-based resonant cavity interferometer
Granted: May 29, 2003
Application Number:
20030098982
A truncated series-based cavity interferometer contains a multi-reflection cavity upon which an input light beam is directed at an acute angle, to produce a spatially spread series of multiple order beams through which the transfer function (e.g., a generally square pass/stop profile) of the interferometer is defined. Because the input beam is incident upon the cavity at an acute angle, it is non counter-propagating with respect to the reflected beam, so that no circulator is required…
Method of reducing a hydrogen content of an optical fiber or preform
Granted: May 8, 2003
Application Number:
20030084684
The invention provides a method of passivating an optical fiber or preform by reducing a hydrogen content in the fiber or preform using a deuterium ion plasma passivation process or a high temperature deuterium gas passivation of preforms for exchanging at least a portion of the hydrogen contained within the optical fiber or preform with deuterium. The deuterium plasma is generated from a deuterium gas. To further reduce the passivation, the optical fiber or preform are heated in the…
Method of making an optical fiber or preform having a reduced hydrogen content
Granted: May 8, 2003
Application Number:
20030084685
The invention provides a method of making an optical fiber preform using a modified chemical vapor deposition process by flowing glass precursor gases through a preform tube for depositing glass material therein, and simultaneously flowing heavy water vapors through the preform tube for incorporating deuteroxyl groups into the glass material. Then, the preform tube is controllably heated so as to effect a collapse of the preform tube into a rod. Advantageously, optical fibers drawn from…
Package for optical components
Granted: May 8, 2003
Application Number:
20030085212
A package for optical components includes an inner package enclosing the optical component, and an outer package enclosing the inner package. A heater may be disposed in the inner package proximate the optical component to control its temperature, and to maintain this temperature control, the outer package creates an isolated air pocket around the inner package, which thermally insulates the inner package from the outside environment. The outer package is formed of a material having low…
Method and apparatus for setting gain and tilt in spectral performance of fiber amplifiers
Granted: May 8, 2003
Application Number:
20030086153
An apparatus for sensing changes, e.g. transient changes in the input or output signal spectrum of an optical amplifier, typically an EDFA, uses only a pair of spectrally banded photodiodes to equalize the transient behaviour of the amplifier. The photodiodes provide a control signal which is either sum or difference of signals generated by the photodiodes, that is used in the control of the optical amplifier in a feedback or feed-forward mode in order to counterbalance the effects of…
Highly tunable dispersion compensator
Granted: May 8, 2003
Application Number:
20030086168
A method and device for providing tunable dispersion compensation by splitting an incoming optical beam and then recombining interferometrically two sub-beams which have been passed through fixed dispersive (dispersion producing) elements. The polarization of the incoming optical signal is controlled and the signal beam is split into sub-beams at a ratio dependent on the polarization. The sub-beams are directed to each of two interferometer arms. The return beams are interfered e.g. by…
Optical bit rate detector
Granted: May 1, 2003
Application Number:
20030081200
The invention relates to a simple and relatively inexpensive way of determining the optical bit rate of an optical signal, which is based on the fact that different percentages of the signal will be transmitted through a narrow-band optical filter depending on the bit rate. Increasing the bit rate of an optical signal results in a broadening of the channel spectrum, therefore, if the optical filter is designed with a passband thinner than all (or all but one) of the channel widths, then…
Method of fabricating optical fiber preforms with high dopant concentration and good geometry
Granted: April 24, 2003
Application Number:
20030077055
An optical fiber preform is made by modifying a conventional preform tube having a cladding zone and a core zone, before its thermal collapse normally followed by fiber drawing. The modification is accomplished by depositing, e.g. by MCVD, a thin protective layer of a light-transmissive material, e.g. silica, on the inner surface of the preform tube, over the core zone, before the collapse step. The material of the protective layer has a higher viscosity than the material of the core…
Electrode structure including encapsulated adhesion layer
Granted: April 3, 2003
Application Number:
20030062551
The present invention relates to methods for forming metalized structures, such as electrodes, on non-conductive substrates of electronic and electro-optic devices for enhanced corrosion resistance. In the method of the present invention, an electrode layer is deposited over an adhesion layer on a substrate surface including all edges of the adhesion layer not in contact with the substrate, thereby encapsulating the adhesion layer within the electrode metal before forming the electrode.…
Dual stage optical isolator with reduced polarization mode dispersion and beam offset
Granted: March 20, 2003
Application Number:
20030053209
A double-stage (multi-stage) optical isolator is composed of two pairs of birefringent wedges (polarizers) with a Faraday rotator sandwiched by a pair of the wedges. The wedge-shaped polarizers, each defining a wedge angle, are disposed such that the wedges of the third and fourth polarizer (second stage) are arranged generally opposite relative to the wedges of the first and second polarizer (first stage) respectively, the wedge angles and the angles of incidence in the forward…
