Abstract: A novel method and apparatus for varying the index of refraction of a material using an interference pattern is disclosed. The method and apparatus incorporate an ultra short duration pulse laser source. Electromagnetic radiation provided from the laser propagates to a diffractive element positioned in close proximity to the target material. The diffracted electromagnetic radiation forms an interference pattern, the peaks of which are sufficiently intense to cause a change in index of refraction.

Abstract: A novel Bragg grating filter in optical waveguiding fiber with suppressed cladding mode coupling and method of producing same is disclosed. The novel grating structure is induced in both the core and the cladding of the optical fiber irrespective of the photosensitivity of the core or cladding to actinic radiation. Such core and cladding of the optical fiber need not be chemically doped to support the grating. The method incorporates an ultra short duration pulse laser source. Electromagnetic radiation provided from the laser propagates to a diffractive element positioned a specific distance to the target material such that the diffracted electromagnetic radiation forms a 2-beam interference pattern, the peaks of which are sufficiently intense to cause a change in index of refraction.

Abstract: A novel method and apparatus for varying the index of refraction of a material using an interference pattern is disclosed. The method and apparatus incorporate an ultra short duration pulse laser source. Electromagnetic radiation provided from the laser propagates to a diffractive element positioned in close proximity to the target material. The diffracted electromagnetic radiation forms an interference pattern, the peaks of which are sufficiently intense to cause a change in index of refraction.

Abstract: A polarization compensator is disclosed for passing light in a predetermined wavelength range. The compensator has unequal output orthogonal polarizations for light launched into the device within a specific wavelength range. A waveguide having a blazed grating having a blaze angle &thgr;b1 of between 20° and 45° with respect to the optical axis of the waveguide exhibits a tap efficiency difference for orthogonal polarizations for offsetting and lessening a polarization dependence of the device. This waveguide is optically coupled with the optical device requiring polarization compensation. The grating is oriented about its optical axis to lesson the inequality in output orthogonal polarizations for light launched into the optical device.

Abstract: 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.

Abstract: A polarization compensator is disclosed for passing light in a predetermined wavelength range. The compensator has unequal output orthogonal polarizations for light launched into the device within a specific wavelength range. A waveguide having a blazed grating having a blaze angle &thgr;b1 of between 20° and 45° with respect to the optical axis of the waveguide exhibits a tap efficiency difference for orthogonal polarizations for offsetting and lessening a polarization dependence of the device. This waveguide is optically coupled with the optical device requiring polarization compensation. The grating is oriented about its optical axis to lesson the inequality in output orthogonal polarizations for light launched into the optical device.

Abstract: 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.

Abstract: 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.

Abstract: A device for distributing an optical signal has an optical waveguide with a plurality of gratings disposed in series therein, the gratings having a predetermined reflectivity response within a specific wavelength range; an optical circulator having at least three ports, one of the ports serving as an input port for receiving the optical signal, and another port for removing at least a part of the optical signal reflected from one of the gratings; and control means for individually controlling at least some of the gratings to effect a change of the wavelength range of the reflectivity response of the gratings. The change may be a shift, an expansion or a compression of the range. The device can function as a signal distributor (router), an equalizer or a demultiplexer. The reflectivity response is preferably a sloped response.

Abstract: An attenuator capable of controllably attenuating at least two wavelengths of light is configured to have an optical waveguide section having at least two Bragg gratings disposed therein in series. The Bragg gratings have a sloped reflectivity response within a predetermined wavelength range. The sloped response is a function of refractive index variations within each of the grating elements. By compressing or expanding at least one of the gratings, the periodicity is modified so as to shift its central wavelength within a predetermined wavelength range.

Abstract: A bandpass optical filter is provided that is formed within an optical fiber in the form of a Bragg grating. The grating includes multiple Fabry Perot cavities disposed along the waveguide. Each of the cavities includes a pair of reflectors. Each reflector comprises alternating high-low index regions within the waveguide, each region having a thickness of one quarter-wave at a bandpass wavelength, each alternate region being of a different index of refraction than an adjacent region. A multiple odd quarter-wave or quarter-wave high or low index region is sandwiched between each pair of reflectors. The number of high/low regions within a reflector is selected in accordance with the refractive index difference between two alternate adjacent regions.