摘要:
An optical fiber filter including a length of single mode fiber having an operating wavelength .lambda..sub.0. Fiber designs may include a depressed inner clad fiber, a photosensitive matched inner clad fiber or a photosensitive depressed inner clad fiber. The length of fiber includes a core, an inner cladding, an outer cladding and an azimuthally asymmetric grating. The core allows the existence of a LP.sub.01 core mode having an effective index of n.sub.eff,01 and the cladding allows the existence of a LP.sub.1m cladding mode, m.gtoreq.1. The core has an index of refraction n.sub.co and a radius A. The inner cladding has an index of refraction n.sub.ic, an inner radius A, an outer radius AB, a thickness W, where W=AB-A, and a refraction difference .DELTA.n-, where .DELTA.n- is the difference between n.sub.ic and n.sub.oc and n.sub.co >n.sub.oc >n.sub.ic. The inner cladding may be photosensitive to a radius R.sub.grat and have a fractional photosensitivity .gamma.. The outer cladding generally laterally surrounds the inner cladding and has an inner radius AB, an outer radius B, and an index of refraction n.sub.oc, where .DELTA.n.sub.+ is the difference between n.sub.co and n.sub.oc. The grating has an effective tilt angle .theta. and a period (.LAMBDA.), where .LAMBDA..ltoreq.(.lambda..sub.0 cos .theta.)/(2n.sub.eff,01), the maximum relative coupling coefficient for the cladding mode max(RCC.sub.1m) being greater or equal to 0.2 and the ratio of peak reflectivities for the cladding mode and the core mode RR being greater or equal to 1.
摘要:
A waveguide, such as an optical fiber waveguide for guiding light waves, which can provide a strongly reflective grating (e.g., a Bragg grating) at a specified wavelength while maintaining very low losses at adjacent wavelengths. The waveguide includes a core, an inner cladding laterally surrounding the core, an outer cladding laterally surrounding the inner cladding, and a grating pattern. The core has a refractive index n.sub.co and a first transverse dimension 2A. The inner cladding has a width W and a refractive index n.sub.ic. The outer cladding has a refractive index n.sub.oc. The relation between the refractive indexes, n.sub.co >n.sub.oc >n.sub.ic and 0.5
摘要:
A fiber optic, Faraday-effect sensing coil has very low linear and circular birefringence, which remains stable over a wide range of temperatures. The coil is fabricated from a spun fiber having an effective linear beat length of 100 meters or more, and is annealed after being formed into the coil. The coil has improved discrimination for magnetic fields associated with electric current-carrying cables, and may be incorporated into an optical current transducer (OCT), either interferometric or polarimetric.
摘要:
An optical waveguide comprises a core, an inner cladding laterally surrounding the core, and an outer cladding laterally surrounding the inner cladding, wherein the core, inner cladding, and outer cladding have a depressed well configuration. The waveguide operates in three or more wavelength bands, wherein a first wavelength band is centered at about 1300 nm, and wherein a second wavelength band is centered at about 1625 nm. The waveguide has bend losses that are less than or equal to 0.7 dB/turn when measured on a 10 mm radius bend at 1625 nm.
摘要:
A fiber optic telecommunication system with a pump laser and an optical amplifier is designed to stabilize the pump laser while preventing back reflections from the pump laser into the optical amplifier. The pump laser emits radiation at a shorter wavelength, while the optical amplifier emits radiation at a longer wavelength. An optical fiber is provided to connect the devices which has an ultraviolet photosensitive core, a low attenuation single mode wavelength region and a very high attenuation, longer wavelength region. The photosensitive core allows a weak Bragg grating to be written into the fiber, to stabilize the pump laser. Apparent fundamental mode cutoff is accomplished with a depressed well design to attenuate the unwanted back reflections from the pump laser into the amplifier. The pump laser is also protected from longer wavelength signal amplifier or signal laser radiation.
摘要:
A method for making a V-shaped highly birefringent optical fiber includes providing a preform with a substantially circular cross section. The outer surface of preform is modified to create a shaped preform with a substantially V-shaped cross section. The shaped preform is then drawn at a temperature and draw rate sufficient to provide an optical fiber with the V-shaped cross section of the shaped preform.
摘要:
A single-mode optical fiber that includes: (a) a core that includes silica and is characterized by a first refractivity that changes upon exposure to actinic radiation of a predetermined wavelength; and (b) a cladding surrounding the core that also includes silica and is characterized by a second refractivity different from the first refractivity that changes upon exposure to actinic radiation of a predetermined wavelength. At least one of the core and the cladding further includes boron, the relative amounts of boron in the core and cladding being selected such that the first refractivity and the second refractivity change by substantially the same amount upon exposure to actinic radiation of a predetermined wavelength.
摘要:
A method for making a highly birefringent optical fiber includes providing a preform with a substantially circular cross section. The preform includes a core region having a substantially circular cross section and a substantially elliptical cladding region adjacent the core region. The outer surface of the preform is modified to create a shaped preform with a non-circular cross section. The shaped preform is then drawn at a temperature and draw rate sufficient to provide an optical fiber with the non-circular cross section of the shaped preform.
摘要:
A fiber optic, Faraday-effect sensing coil has very low linear and circular birefringence, which remains stable over a wide range of temperatures. The coil is fabricated from a spun fiber having an effective linear beat length of 100 meters or more, and is annealed after being formed into the coil. The coil has improved discrimination for magnetic fields associated with electric current-carrying cables, and may be incorporated into an optical current transducer (OCT), either interferometric or polarimetric.