Abstract: Optical waveguides having a waveguide channel of photosensitive silica glass with a modified refractive index optically written therein, wherein the photosensitive glass comprises oxides of silicon, tin and at least one Group I element, where such optical waveguide devices include optical fiber gratings, optical fiber dispersion compensators, optical fiber sensors, optical fiber lasers, and planar waveguide devices.

Abstract: The present invention relates to a method and apparatus for tuning an optical fiber based optical device. An optical fiber device in accordance with the present invention is held at a first tension, and in accordance with the method of the present invention, heat is applied to the fiber to cause a release of tension. This can be used effectively to provide accurately tuned in-fiber Bragg gratings, or to trim fiber based interferometers. Advantageously, tuning method is significantly simplified over prior art methods. A further advantage is realized in that multiple fiber Bragg gratings can be packaged together and tuned separately, including multiple fibers or multiple gratings in a single fiber.

Abstract: A photosensitive glass made of a ternary compound SiO2:SnO2:R2O where R is a Group I element such as Na, K or Li. The addition of an oxide of a Group I element increases the solubility of tin oxide in a silica matrix and produces a glass which is highly photosensitive and in which optically written refractive index modulations have remarkable temperature stability (solid circles) at least as good as that of the binary glass SiO2:SnO2 (open circles) and much superior to that of conventional germanosilicate glass (solid triangles) or borogermanosilicate glass (open triangles). The inclusion of the Group I oxide effectively increases the solubility of tin oxide in the non-crystalline silica matrix well above the 1% limit of SiO2:SnO2 photosensitive glass, at which Sn would normally crystallize in the oxide.

Abstract: A method of forming a chirped fiber grating having the steps of providing an optical fiber, impressing a non-linear grating onto a portion of the optical fiber to define a non-linear variation in the refractive index. The method further comprising applying a temperature gradient to a portion of the optical fiber to provide a variation that acts against the non-linear variation in the refractive index.

Abstract: PURPOSE: To increase the mechanical strength of a connected optical fiber, by carrying out a surface treatment by dipping the melt-struck connection part of the optical fiber in a treating liquid of strong acid and then in a treating liquid of hydrofluoric acid. CONSTITUTION: A treatment liquid 6 of a mixture solution consisting of 1 or ≧2 kinds of strong acid such as sulfuric acid, hydrochloric acid, nitric acid, etc. is stored in a liquid tank 7. A melt-stuck connection part 5 of end parts 2A and 2B of optical fibers 1A and 1B is dipped in the tank 7. Thus coat residue, dust, metallic particles, etc. sticking to the surface of the part 5 are removed. Then the part 5 is dipped in a treating liquid containing an aqueous solution of hydrofluoric acid, ammonium fluoride, sodium fluoride in a liquid tank 8. Thus the minute flaws on the surface are removed or annealed. As a result, the strength is increased at the part 5.

Abstract: An optical fiber transmission system comprises an optical signal source operable to generate an optical signal at a predetermined bit rate and at a signal wavelength; an optical fiber transmission link connected at a first end to the signal source, the link having dispersion characteristics at the signal wavelength; an optical amplifier serially disposed in the link; and a signal receiver connected at the second end of the Lank; in which a grating is connected in the link, the grating being chirped by an amount providing at least partial compensation of the dispersion characteristics of the link, the compensation such as to provide a signal, at the second of the link, compatible with the sensitivity requirements of the receiver at the second end of the link.

Abstract: A coated optical fiber comprises a coating, an optical fiber, at least one waveguiding region and an index grating. The waveguiding region contains at least one photosensitive region, the index grating is formed by writing through the coating using UV light, and the coating transmits UV light at the wavelength at which the index grating is written.

Abstract: The invention provides a method of manufacturing a chirped optical fiber grating, the method comprising the steps of an etching the cladding of the optical fiber to vary the cross-sectional area of a portion of an optical fiber, and impressing a grating of uniform pitch on the portion of the fiber in which the portion of the fiber is subjected to different respective longitudinal forces during the impressing step and during subsequent use of the grating.

Abstract: An optical fiber transmission system comprises an optical signal source operable to generate an optical signal at a predetermined bit rate and at a signal wavelength; an optical fiber transmission link connected at a first end to the signal source, the link having dispersion characteristics at the signal wavelength; an optical amplifier serially disposed in the link; and a signal receiver connected at the second end of the Lank; in which a grating is connected in the link, the grating being chirped by an amount providing at least partial compensation of the dispersion characteristics of the link, the compensation such as to provide a signal, at the second of the link, compatible with the sensitivity requirements of the receiver at the second end of the link.

Abstract: An optical fiber comprises a glass core having a core refractive index; a glass primary cladding at least partially surrounding said core, said primary cladding having a primary cladding refractive index lower than said core refractive index; a glass secondary cladding at least partially surrounding said primary cladding, said secondary cladding having a secondary cladding refractive index lower than said core refractive index but higher than said primary cladding refractive index; said glass of said core and said glass of at least part of said primary cladding containing one or more photosensitizing dopants.

Abstract: An optical fiber has a cladding glass layer surrounding a glass core, in which a region (preferably annular) of the optical fiber partially overlapping the cladding and/or the core is formed of photosensitive glass.

Abstract: An optical fibre distributed feedback laser comprises an amplifying optical fibre (50) operable to provide optical gain at a lasing wavelength, in which a diffraction grating (30) is disposed on at least a portion of the amplifying optical fibre to provide distributed optical feedback for sustaining lasing action at the lasing wavelength.

Abstract: An active device (FIG. 1) comprising a length of doped fiber (1) and an end-coupled pump source (11). The fiber (1) is of single-mode geometry and incorporates rare-earth or transition metal dopant ions. These latter are incorporated at a low-level uniform concentration (.ltorsim.900 ppm). The fiber host (1) selected exhibits an inherently ultra low attentuation loss (.ltorsim.40 dB/km) at the emission wavelength. The fibers (1) are generally of long length (e.g. 5 m to 300 m) and may be coiled for compact packaging. The fiber (1) may be formed as part of a Fabry-Perot cavity (1, 7, 9); or, as a ring cavity (FIG. 8) using a doped fiber coupler (29) spliced to form a ring (27). Q-switch and mode-locking devices (19) and gratings (25) may be included as part of the Fabry-Perot cavity to allow pulse-mode operation and/or wavelength tuning, respectively. The fiber (1) may also be utilised as an amplifier.

Abstract: A fibre laser (1) of the type comprising a doped single-mode optical fibre (3) arranged between reflectors (5,7), and which is coupled (11) to an optical pumping source (9). For the given reflection efficiency of the reflectors (5,7), the length of the optical fibre (3) is chosen such that it exceeds that affording saturation and provides at its end a region for absorption (FIG. 1). The resultant hysteretic behavior of this bistable device may be utilized for logic memory (bistable), and regenerative amplification applications. To this end a second source (9') can be coupled (11',19) to the laser fibre (3).

Abstract: A method of making a preform for drawing optical fibers includes the steps of depositing a dopant material 3 in a dopant carrier chamber 1, heating the dopant material to cause it to vaporise at a predetermined rate, depositing from a mixture of a source material (GeCl.sub.4, SiO.sub.4, O.sub.2) and said vaporised dopant a mixture of solid components 8 and fusing said solid components to form a doped glass.