Her Majesty the Queen in Right of Canada, As Represented by the Minister

Canadian Patents & Development Ltd.

Her Majesty the Queen in Right of Canada As Represented by the Minister of Industry Through the Communications Research Centre Canada

Canadian Patents and Development Limited/societe Canadienne Des Brevets

Her Majesy in Right of Canada As Represented by the Minister of Communications

Francois C Bilodeau

Kenneth O Hill

Derwyn C Johnson

Bernard Y Malo

Stephen J Mihailov

Jacques Albert

Sylvain Faucher

Seyed-Iraj Najafi

A device for providing an expanded mode field from a single mode optical waveguide is formed by fusing a length of single mode optical fiber with a length of fiber rod absent a cladding and adiabatically tapering the fused region. The length of single mode fiber has a core having a refractive index nand a cladding having a refractive index n, wherein n&#x3c;nand wherein the cladding has an outer diameter &#x3c1;. The length of fiber rod absent the cladding has a refractive index of the fiber rod is substantially the same as the cladding index nof the single mode optical fiber. The outer diameter of the length of fiber rod is &#x3c1;, the same as the cladding diameter of the single mode fiber.

Optical fiber fundamental mode field expander

An index grating is imprinted in the core of an optical fiber using a specially designed silica glass phase grating mask. The phase mask is held in close proximity to the optical fiber. Laser irradiation of the phase mask with ultraviolet light at normal incidence imprints (photoinduces) into the optical fiber core the interference pattern created by the phase mask.

Method of fabricating Bragg gratings using a silica glass phase grating mask and mask used by same

A method is disclosed wherein optical structures such as Bragg gratings can be written into planar waveguides disposed on a substrate. By employing the method of this invention, a polarization insensitive device can be made. Such relatively thin planar waveguides disposed on a substrate are inherently polarization sensitive and the structure itself is birefringent. By writing structures in the waveguides or by simply writing a refractive index change in the waveguide by limiting the beam width at the waveguide layer to less than or equal to the thickness of the waveguiding layers on the substrate, in combination with conventional wider beam writing techniques, polarization sensitivity can be lessened or obviated.

Polarization insensitive grating in a planar channel optical waveguide and method to achieve the same

A method of fabricating a strongly photosensitive optical waveguide is comprised of locally heating at least a portion of a weakly photosensitive optical waveguide for a period of time sufficient to increase the density of defects associated with photosensitivity in the heated portion of the waveguide core.

Photosensitization of optical fiber and silica waveguides

Method of fabricating Bragg gratings using a silica glass phase grating

Efficient, narrow-band rocking filters have been made in polarization-maintaining monomode optical fiber by photoinducing periodic birefringent gratings along the length of the fiber. These gratings, fabricated with a period chosen to provide synchronous coupling between the two principal states of polarization of the LP.sub.01 mode at a preselected wavelength, gently rock to and fro the principal polarization axes of the fiber. To photoinduce the grating, the fiber is exposed periodically along its length to a U.V. light beam which is incident at right angles to the geometrical axis of the fiber and is directed .pi./4 radians with respect to the principal axes. Efficient polarization mode conversion at 1.3 .mu.m with the fiber gratings are obtained.

Method of creating an index grating in an optical fiber and a mode

A two-channel optical fiber fused coupler comprising two optical fibers, each with a core and cladding, fused together at a narrow tapered waist. The first channel is at a wavelength of .lambda..sub.1 and the second channel is at a wavelength of .lambda..sub.2 where .lambda..sub.2 is longer than .lambda..sub.1. The coupler is fabricated to have a characteristic wavelength .lambda..sub.0 such that for wavelengths .lambda..sub.2 longer than .lambda..sub.0 coupling occurs and for wavelenghts .lambda..sub.1 shorter that .lambda..sub.0 the light at .lambda..sub.1 is core guided throughout the coupler and thus does not couple across.

Simplified WDM fused fiber coupler design

This invention relates to a method of creating an index grating in an optical fiber comprising disposing a slit mask containing one or more slits over a side of an optical fiber, illuminating the fiber through the slit mask by substantially monochromatic ultraviolet light for a short interval, whereby an index grating line is created and stored in the core of the fiber.

The present disclosure makes a grating assisted optical waveguide device. The method includes cleaning a substrate made of glass by means of cleaning agents; depositing a first layer made of metal onto a surface of the substrate by an evaporation process; forming a first mask by making openings in the first layer to expose first parts of the surface, the first mask being formed by a photolithographic process; immersing the substrate in a first bath of molten salt having a first preselected temperature to make a waveguide by increasing the refractive index of the glass in the first parts by an ion-exchange process; removing the first mask from the surface; immersing the substrate in a second bath of molten salt in order to bury the waveguide; depositing a second layer made of metal on the surface of the substrate by an evaporation process; forming a second mask by making openings in the second layer to expose second parts of the surface, the second mask being formed by a photolithographic process; immersing the substrate in a third bath of molten salt having a third preselected temperature to change the refractive index of the glass in the second parts by an ion-exchange process in order to form a grating, the refractive index obtained in this third immersing step being different from the refractive index obtained in the first immersing step, the third preselected temperature being lower than the first preselected temperature to avoid further diffusion of ions diffused in substrate in the first bath; and removing the second mask from the surface to obtain the grating assisted optical waveguide device.

Method for making a grating assisted optical waveguide device

New types of narrowband wavelength selective optical devices are described. Various configurations are possible, according to the invention, that perform as narrowband wavelength selective transmission or reflection filters or as narrowband wavelength selective optical taps or combiners. The optical devices of the invention include a 3 dB optical directional coupler and wavelength selecting elements such as Bragg reflection gratings or Fabry-Perot resonators usually positioned in optical symmetry with respect to the directional coupler. Two or more wavelength selecting elements can be used to obtain desired filtering characteristics.

Wavelength selective optical devices using optical directional coupler

A method of forming a single mode biconical fiber optic coupler comprising holding 2 or more optical fibers parallel to and in contact with each other at spaced apart locations, exerting equal tension in opposite directions to the fibers at said spaced apart locations to stretch the fibers, fusing the fibers over a waist region, and scanning the tip of a flame from a microtorch back and forth along the fibers at a speed which is at least five times the speed of stretching of the fibers. This results in an overcoupled low loss coupler, a pressure or a temperature sensor, comprised of at least a pair of monomode optical fibers fused and parallel at a stretched waist portion, each having biconical tapers at opposite ends of the waist portion, the coupler having exhibited at least about 500 power transfer cycles during stretching formation of the waist portion.

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Nepean, Canada

Francois C Bilodeau