Abstract: A compression-tuned Bragg grating-based laser 800 includes a pair of optical grating elements 802,804 wherein at least one of the grating elements is tunable by a compression device 812,814. The grating elements may include either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20 or a large diameter waveguide grating element 600 having a core and a wide cladding. The tunable grating element(s) 802,804 are axially compressed, which causes a shift in the reflection wavelength of the gratings 807,809 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. A gain element, such as Erbium doped fiber, is optical disposed between the grating elements to provide the lasing cavity.

Abstract: A tunable optical filter filters is provided that has a pair of tunable Bragg grating units optically coupled to respective ports of a 4-port circulator for filtering a selected wavelength band or channel of light from a DWDM input light. Each grating unit includes an array of Bragg gratings written or embedded within a respective tunable optical element to provide a tunable optical filter that functions over a wide spectral range greater than the tunable range of each grating element. The reflection wavelengths of the array of gratings of each respective grating element is spaced at a predetermined spacing, such that when a pair of complementary gratings of the grating elements are aligned, the other complementary gratings are misaligned. Both of the optical elements may be tuned to selectively align each complementary grating over each corresponding spectral range.

Abstract: A tunable dispersion compensating device includes a grating element in the form of a bulk or large diameter waveguide, having an outer cladding disposed about an inner core. The grating element may be etched, grounded or machined to form a generally “dog bone” shape, wherein the end portions of the grating element has a larger diameter than the center portion disposed therebetween. A chirped grating is written or impressed within the portion of the core disposed in the center portion of the grating element. The center portion is tapered to allow different stresses to be applied along the grating length when the grating element is compressed longitudinally by force F, and thereby vary chirp of the grating to tunably compensate for dispersion.

Abstract: An optical filter, including a Bragg grating, is compression tuned such that when under one compressional load (or no load) the grating has a first profile and under a second compressional load the grating has a second profile. One application is to allow the grating filter function to be parked optically between channels of a WDM or DWDM optical system.

Abstract: A tube-encased fiber grating includes an optical fiber 10 having at least one Bragg grating 12 impressed therein which is embedded within a glass capillary tube 20. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength &lgr;1. The shape of the tube 20 may be other geometries (e.g., a “dogbone” shape) and/or more than one concentric tube may be used or more than one grating or pair of gratings may be used. The fiber 10 may be doped at least between a pair of gratings 150,152, encased in the tube 20 to form a tube-encased compression-tuned fiber laser or the grating 12 or gratings 150,152 may be constructed as a tunable DFB fiber laser encased in the tube 20. Also, the tube 20 may have an inner region 22 which is tapered away from the fiber 10 to provide strain relief for the fiber 10, or the tube 20 may have tapered (or fluted) sections 27 which have an outer geometry that decreases down to the fiber 10 and provides added fiber pull strength.

Abstract: A compression-tuned Bragg grating-based laser 800 includes a pair of optical grating elements 802,804 wherein at least one of the grating elements is tunable by a compression device 812,814. The grating elements may include either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20 or a large diameter waveguide grating element 600 having a core and a wide cladding. The tunable grating element(s) 802,804 are axially compressed, which causes a shift in the reflection wavelength of the gratings 807,809 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. A gain element, such as Erbium doped fiber, is optical disposed between the grating elements to provide the lasing cavity.

Abstract: A fiber grating pressure sensor includes an optical sensing element 20,600 which includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20,600 may be used by itself as a sensor or located within a housing 48,60,90,270,300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20,600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50.

Abstract: A large diameter D-shaped optical waveguide device 9, includes an optional circular waveguide portion 11 and a D-shaped waveguide portion 10 having at least one core 12 surrounded by a cladding 14. A portion of the waveguide device 9 has a generally D-shaped cross-section and has transverse waveguide dimension d2 greater than about 0.3 mm. At least one Bragg grating 16 may be impressed in the waveguide 10 and/or more than one grating or pair of gratings may be used and more than one core may be used. The device 9 provides a sturdy waveguide platform for coupling light into and out of waveguides and for attachment and alignment to other waveguides, for single and multi-core applications. The core and/or cladding 12,14 may be doped with a rare-earth dopant and/or may be photosensitive. At least a portion of the core 12 may be doped between a pair of gratings 50,52 to form a fiber laser or the grating 16 or may be constructed as a tunable DFB fiber laser or an interactive fiber laser within the waveguide 10.

Abstract: A fused tension-based fiber grating pressure sensor includes an optical fiber having a Bragg grating impressed therein. The fiber is fused to tubes on opposite sides of the grating and an outer tube is fused to the tubes to form a chamber. The tubes and fiber may be made of glass. Light is incident on the grating and light is reflected from the grating at a reflection wavelength &lgr;1. The grating is initially placed in tension as the pressure P increases, the tension on the grating reduced and the reflection wavelength shifts accordingly. A temperature grating may be used to measure temperature and allow for a temperature-corrected pressure measurement.

Abstract: An optical coupling device is provided for coupling a pump light into an optical waveguide such as an optical fiber or planar waveguide. An optical source provides a pump light. A large diameter optical waveguide is arranged in relation to the optical source, has a diameter substantially greater than 0.3 microns, and includes a reflective surface that reflects the pump light and provides a reflected pump light to the optical fiber. The reflective surface may be either a notched surface of a V-shaped indentation or a cleaved end of the large diameter optical waveguide. Alternatively, the optical coupling device is includes a side tap lens mounted to the large diameter optical waveguide for directing pump light provided by the optical source. The side tap lens is arranged in relation to the optical source and includes a reflective surface that reflects the pump light and provides a reflected pump light to the large diameter waveguide, which directs the pump light to the optical fiber.

Abstract: A pressure-isolated Bragg grating temperature sensor includes an optical element 20,600 which includes an optical fiber 10 having at least one Bragg grating 12 disposed therein which is encased within and fused to at least a portion of an inner glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and having the grating 12 disposed therein, which is encased within an outer tube 40 to form a chamber 44. An extended portion 58 of the sensing element that has the grating 12 therein extends inwardly into the chamber 44 which allows the grating 12 to sense temperature changes but isolates the grating 12 from external pressure. An end tube 42 may be attached to the tube 40 and the fiber 10 fed therethrough to form the chamber 44 and a pass-through for the fiber 10. As the external pressure P increases, the outer tube 40 compresses or deflects, the sensing element 20,600 moves closer to the end tube 42 and/or the outer tube 40 move toward each other.

Abstract: A fiber grating pressure sensor for use in an industrial process includes an optical sensing element 20,600 which includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20,600 may be used by itself as a sensor or located within a housing 48,60,90,270,300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20,600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50.

Abstract: A tunable external cavity semiconductor laser incorporating a tunable Bragg grating, including: a semiconductor gain medium; an elongated tuner housing having a tuner housing head and having a tuner housing foot, the tuner housing head and tuner housing foot being rigidly connected; a span of waveguide having a Bragg grating, for receiving the source light and for providing in turn the reflected light, and having a waveguide head and a waveguide foot, the waveguide head abutting the tuner housing head and the waveguide foot disposed toward the tuner housing foot; a piezoelectric crystal or other device or arrangement for providing a compressive force, disposed so as to abut the waveguide foot and also to abut the tuner housing foot, the means for applying a compressive force for exerting a compressive force on the span of waveguide along the direction of the axis of the span of waveguide, the compressive force being sufficient to alter the grating so as to affect the wavelength of light reflected by the grati

Abstract: A multi-core optical waveguide 10, such as a dual core waveguide, having a pair of cores 12,14 disposed within a cladding 13 is provided. The cores are equally spaced and parallel to the axis of the waveguide. The cores can be spaced to provide optical coupling between the cores. The outer dimension d2 of the cladding 13 is at least about 0.3 mm; and the outer dimension d1 of the cores 12,14 is such that they propagate in a single spatial mode. The multi-core waveguide may be used in many optical components, such as a bandpass filter and an optical add/drop multiplexer. For the bandpass filter, a Bragg grating having the same reflection wavelength is written into both cores at substantially the same distance from the input end 86,87 of the cores. The cores 12,14 have the same propagation constants to permit coupling of all the energy of the WDM input signal 84 from one core to the other.

Abstract: A pressure-isolated Bragg grating temperature sensor includes an optical element which includes an optical fiber having at least one Bragg grating disposed therein. The Bragg grating is encased within and fused to at least a portion of an inner glass capillary tube, or comprises a large diameter waveguide grating having a core and a wide cladding and having the grating disposed therein, encased within an outer tube to form a chamber. An extended portion of the sensing element that has the grating therein extends inwardly into the chamber which allows the grating to sense temperature changes but isolates the grating from external pressure. More than one grating or pair of gratings may be used and more than one fiber or optical core may be used. At least a portion of the sensing element may be doped between a pair of gratings to form a temperature tuned laser, or the grating or gratings may be configured as a tunable DFB laser disposed in the sensing element.

Abstract: A fiber grating pressure sensor includes an optical sensing element 20, 600 which includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within and fused to at least a portion of a glass capillary tube 20 and/or a large diameter waveguide grating 600 having a core and a wide cladding and which has an outer transverse dimension of at least 0.3 mm. Light 14 is incident on the grating 12 and light 16 is reflected from the grating 12 at a reflection wavelength &lgr;1. The sensing element 20, 600 may be used by itself as a sensor or located within a housing 48, 60, 90, 270, 300. When external pressure P increases, the grating 12 is compressed and the reflection wavelength &lgr;1 changes. The shape of the sensing element 20, 600 may have other geometries, e.g., a “dogbone” shape, so as to enhance the sensitivity of shift in &lgr;1 due to applied external pressure and may be fused to an outer shell 50.

Abstract: An apparatus and method for interrogating fiber optic sensors non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a two beam interferometer which comprises an optics circuit for generating a series of discrete light pulses that are directed at sensors positioned between pairs of low reflectivity fiber Bragg gratings. The successive light pulses are split into first light pulses and second light pulses and the second light pulses are delayed a known time period relative to the first pulses. The first and second light pulses are combined onto a single optical fiber and directed through the low reflectivity gratings and the sensor positioned between the gratings. Reflected pulses from the series of pulses impinge on a photo receiver and interrogator wherein the phase shift between the reflected first light pulses from the second grating and the reflected second light pulses from the first grating for each sensor are determined.

Abstract: A compression-tuned bragg grating includes a tunable optical element 20,600 which includes either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20or a large diameter waveguide grating 600 having a core and a wide cladding. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength &lgr;1. The tunable element 20,600 is axially compressed which causes a shift in the reflection wavelength of the grating 12 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. At least a portion of the element may be doped between a pair of gratings 150,152, to form a compression-tuned laser or the grating 12 or gratings 150,152 may be constructed as a tunable DFB laser.

Abstract: A tunable optical filter filters is provided that has a pair of tunable Bragg grating units optically coupled to respective ports of a 4-port circulator for filtering a selected wavelength band or channel of light from a DWDM input light. Each grating unit includes an array of Bragg gratings written or embedded within a respective tunable optical element to provide a tunable optical filter that functions over a wide spectral range greater than the tunable range of each grating element. The reflection wavelengths of the array of gratings of each respective grating element is spaced at a predetermined spacing, such that when a pair of complementary gratings of the grating elements are aligned, the other complementary gratings are misaligned. Both of the optical elements may be tuned to selectively align each complementary grating over each corresponding spectral range.

Abstract: A compression-tuned fiber Bragg grating based reconfigurable wavelength add/drop module has a compression force assembly and an all-glass Bragg grating compression unit having gratings spaced along an axis of compression. The compression force assembly responds to a control electronics signal containing information about a selected wavelength of a channel to be added to or dropped from an optical traffic signal, for providing a compression force applied along the axis of compression. The compression unit responds to the optical traffic signal and the compression force, for providing an all-glass Bragg grating compression unit optical signal having the selected wavelength of the channel to be added to or dropped from the optical traffic signal. The compression unit optical signal may include either the traffic with an added reflected channel(s), or a dropped reflected channel(s).