Abstract: An improved optical fiber achieves both reduced bending and microbending losses, as well as a much higher Brillouin threshold, as compared to standard transmission fibers. The optical fiber comprises a core including at least two dopants and having a refractive index difference ?n1 with an outer optical cladding, a first inner cladding having a refractive index difference ?n2 with the outer cladding, and a depressed, second inner cladding having a refractive index difference ?n3 with the outer cladding of less than ?3×10?3. The radial concentration of at least one of the core dopants varies continuously over the entire core region of the optical fiber.

Abstract: An optical fiber sensor enabling simpler detection of a state of an external environment and a measuring apparatus using the same are provided. At a front end of an optical fiber portion 20a for transmitting the light a hetero core having a different diameter from that of a core of the optical fiber portion 20a is melt bonded so as to form a tip type optical fiber sensor 9 having a sensor portion 4 comprised of the hetero core on its front end. An end of the optical fiber portion 20a side of this tip type optical fiber sensor 9 has a light source 1 connected to it. Returned light striking the optical fiber portion 20a from the light source 1 and subjected to interaction with a measurement medium MD at the sensor portion 4 is split by an optical fiber coupler 2 and received at a photodiode or spectrum analyzer 6, thereby an optical fiber sensor measuring apparatus 100 is constructed.

Abstract: An optical waveguide suitable for a slanted Bragg grating (SBG) to be written thereinto has a refractive index profile defining a core and a cladding and a specific photosensitivity profile. This photosensitivity profile W(r) is such that, for a given SBG writing angle ?, the coupling of the fundamental mode into itself as counterpropagation in the waveguide, K(?), is substantially zero and such that its derivative K?(?) with respect to the angle ? is also substantially equal to zero. The zero derivative, and also the zero coupling of the fundamental mode as a function of the angle, means that a widened reflection pocket about the grating write angle is guaranteed.

Abstract: An optical fiber includes an optical fiber axis; a core extending along the axis, the core being made of a first, undoped material having a first refractive index; and a cladding coextensive to and surrounding the core. The cladding includes a background matrix made of the first material and has a plurality of holes formed in the background matrix extending parallel to the fiber axis arranged around the core in substantially concentric rings, and filled with a second material having a second refractive index lower than the first refractive index. The number of the rings of holes is two or three, an average distance between the holes is at least about 6 ?m, a ratio between an effective radius of the core and the average distance between the holes is at most about 1, and a ratio between an average dimension of the holes and the average distance between the holes is at least about 0.5.

Abstract: A large mode area optical fiber is configured to support multiple transverse modes of signal radiation within its core region. The fiber is a hybrid design that includes at least two axial segments having different characteristics. In a first axial segment the transverse refractive index profile inside the core is not radially uniform being characterized by a radial dip in refractive index. The first segment supports more than one transverse mode. In a second axial segment the transverse refractive index profile inside the core is more uniform than that of the first segment. The two segments are adiabatically coupled to one another. Illustratively, the second segment is a terminal portion of the fiber which facilitates coupling to other components. In one embodiment, in the first segment M2>1.0, and in the second segment M22<<M12. In a preferred embodiment, M12>>1.0 and M22˜1.0. In another embodiment, the optical fiber is coupled to a fiber stub.

Abstract: The present invention provides an optical fiber enabling signal transmission in a wider band, which is applicable to optical transmission not only in the 1.3 ?m wavelength band but also in the 1.55 ?m wavelength band, as a transmission medium of a WDM optical communication system capable of transmitting signal light of multiple channels. The optical fiber is comprised of silica glass and has a core region along a predetermined axis and a cladding region provided on the outer periphery of the core region. The optical fiber comprising such a structure has, as the following typical optical characteristics, a cable cutoff wavelength of 1260 nm or less, a transmission loss of 0.32 dB/km or less at the wavelength of 1310 nm, and an OH-related loss increase of 0.3 dB/km or less at the wavelength of 1380 nm.

Abstract: An optical fiber being optically transmissive at a predetermined wavelength of light ? and comprising a plurality of coaxial layers. Each layer having an optical path length that varies radially, the coaxial layers being arranged to give the fiber a refractive index profile which, in use, causes sufficient Fresnel diffraction of the light such that it is guided in the fiber. The refractive index of a cladding region (60) is intermittently suppressed by controlling heating of the preform tube, thus forming a chirped saw-tooth profile (70). The optical fiber may include a lens. In this case, each of the layers has an optical path length that increases gradually outwardly by substantially n×?/2 (n: integer).

Abstract: A core (33) is formed by polymerization of core material that is poured in a hollow part of a tubular inner clad (19) formed inside an outer clad (18). The inner core material comprises a first core monomer having the structural unit of the inner clad (19), a second core monomer different from the first core monomer, and a non-polymerizable refractive index control agent. While the first and second core monomers are copolymerized, the concentration of the refractive index control agent in the core (33) is gradually changed to generate a refractive index profile in the core (33). The second structural unit is the second core monomer can improve heat-resistance of the core (33), and prevent microscopic phase-separation near the interface between the inner clad (19) and the core (33).

Abstract: An optical fiber which, at an optical fiber connecting end having a plurality of voids around the periphery of a core, has a light-permeable substance, such as a resin or glass whose refractive index is lower than that of quartz type substances, filled in the voids adjacent to the connecting end. An optical fiber connecting section where an optical fiber having a plurality of voids in a clad around the periphery of a core is connected to another optical fiber, wherein the optical fiber is connected end-to-end to aforesaid another optical fiber through a refractive index matching agent whose refractive index at the minimum temperature in actual use is lower than that of the core.

Abstract: A high-voltage component, having a first end and a second end, whereby the first end is on a high-voltage potential with respect to the second end. An insulating part, is arranged between the first end and the second end, and an optical fiber is integrated in the high-voltage component and extends from the first end to the second end. A capillary extends from the first end to the second end and is arranged within the insulating part. The inside diameter of the capillary exceeds the outside diameter of the fiber, and the fiber is arranged within the capillary. The capillary includes a protective medium to achieve a dielectric strength in the capillary, which dielectric strength is suitable for the operating conditions.

Abstract: In a glass optical waveguide having a core containing at least one oxide selected from the group of glass-constituting oxides consisting of Bi2O3, Sb2O3, PbO, SnO2 and TeO2, large transmission loss of light which occurs when the cross-sectional shape of the core is rectangle, is reduced, and wherein the glass optical waveguide contains at least total 35% in mass % of at least one type of the above glass-constituting oxides, wherein the cross-sectional shape of the core is trapezoidal, among two parallel sides of the trapezoid, a long side is in a substrate side and among four sides constituting the trapezoid, angles of two oblique sides to the long side are each within a range of from 60 to 80°.

Abstract: The invention relates to an chromatic dispersion-compensating optical fibre in the S-band, for use in compensating for the chromatic dispersion of either a standard SMF optical fibre or of an NZ-DSF optical fibre, carrying an optical signal in the spectral band in use, which is the S-band extending from 1460 nm to 1530 nm. The chromatic dispersion-compensating optical fibre in the S-band has a wavelength corresponding to the global chromatic dispersion minimum, which is situated outside the spectral band in use, that is to say outside the S-band.

Abstract: An optical waveguide comprises a core and is characterised in that the core has a refractive index that includes a radial discontinuity and varies, with increasing azimuthal angle ?, from a first value n2 at a first side of the discontinuity to a second value n1 at a second side of the discontinuity.

Abstract: Apparatus and method are provided for transmitting at least one electro-magnetic radiation is provided. In particular, at least one optical fiber having at least one end extending along a first axis may be provided. Further, a light transmissive optical arrangement may be provided in optical cooperation with the optical fiber. The optical arrangement may have a first surface having a portion that is perpendicular to a second axis, and a second surface which includes a curved portion. The first axis can be provided at a particular angle that is more than 0° and less than 90° with respect to the second axis.

Abstract: A mode field diameter of an optical fiber at a wavelength of 1300 nm is equal to or larger than 5.4 ?m. A light of a wavelength of 1250 nm is propagated through the optical fiber in a single mode. A bending loss of the optical fiber with a bending radius of 1 mm at the wavelength of 1300 nm is equal to or lower than 1 dB/turn.

Abstract: This invention relates to an optical fiber for long period grating (LPG), LPG components, and manufacturing method of LPG used as a mode coupler, an optical filter, etc. The optical fiber for LPG comprises a core layer, a first cladding layer that surrounds said core layer and transmits the cladding modes, and a second cladding layer that surrounds said first cladding layer and confines the optical signal of the cladding mode within said first cladding layer. The LPG component comprises an optical fiber for LPG, a coating reinforcement to cover and reinforce said optical fiber for LPG. The manufacturing method of LPG comprises a step of preparation of an optical fiber, a step of constructing the LPG on a predetermined region in said core of said optical fiber by irradiating laser light on said region over a predetermined period corresponding to the LPG, on the predetermined part of said optical fiber, and a step which covers and reinforces said grating region.

Abstract: The present invention relates to a method of forming a transmission line capable of measuring more precise connection losses at low cost, and so on. At least of first and second optical fibers to be connected as components of the optical transmission line is selected such that, at one wavelength ? contained in the wavelength range of 1260 nm to 1625 nm, predetermined relationships defined by the Rayleigh scattering coefficients of the first and second optical fibers, the mode field diameters of the first and second optical fibers at the wavelength ?, and the transmission losses of the first and second optical fibers at the wavelength ? can be satisfied between the first and second optical fibers.

Abstract: Fiber optic cable systems and methods incorporating a luminescent compound-containing layer to identify cracks. Exemplary embodiments include a fiber optic cable apparatus including a core for receiving laser light emitted from a VCSEL for the detection of faults in the fiber optic cable, a cladding disposed around the core, the cladding having an index of refraction differential with the core thereby allowing containment of light within the core by total internal reflection within the core, a buffer disposed around the cladding, the buffer capable of receiving LED emitted light for the detection of faults in the fiber optic cable, a braiding layer disposed around the buffer and configured to allow LED light to transmit from the buffer, and a jacket disposed around the braiding layer, the jacket having optical properties to receive LED light transmitted down the buffer in response to VCSEL, light having been unsuccessfully transmitted down the core.

Abstract: An optical fiber comprises core and cladding regions configured to guide the propagation of light (or radiation) in the core region. The cladding region includes a periodic structure configured to produce light guiding by bandgap confinement. In order to suppress higher order odes (HOMs) in the core region, the cladding region includes at least one perturbation region configured so that a mode of the cladding region is resonant with a HOM of the core region. In a preferred embodiment of my invention, the perturbation region is configured so that the fundamental mode of the cladding region is resonant with a HOM of the core region.

Abstract: An optical fiber including: (i) a silica based, Yb doped core having a first index of refraction n1, said core comprising more than 1 wt % of Yb, said core having less than 5 dB/km loss at a wavelength situated between 1150 nm and 1350 nm and less than 20 dB/km loss at the wavelength of 1380 nm and slope efficiency of over 0.8; and (ii) at least one silica based cladding surrounding the core and having a second index of refraction n2, such that n1>n2.

Abstract: A microbend-induced fiber grating is formed from a section of optical fiber configured to exhibit “splitting” between the resonant wavelengths supported by the TE and TM components of the LP1m mode and the resonant wavelength supported by the odd/even HE2m components of the LP1m mode. Since only the TE and TM components are polarization dependent, by splitting and shifting the resonant wavelengths for these modes away from a system-desired wavelength(s) supported by the odd/even HE modes, a polarization insensitive microbend-induced fiber grating can be formed. A fiber core configuration including a central core region, trench and ring is formed to exhibit a large radial gradient in core refractive index profile, with a significantly steep transition between the ring index and the trench index, to provide the desired splitting between the (undesired, polarization sensitive) TE/TM modes and the HE mode.

Abstract: A dispersion management system for soliton or soliton-like transmission systems comprises a length of optical fiber (L) in which a plurality of sections (I) made up of components (N,A) of opposite sign dispersions are concatenated together. The duration of the dispersion compensation phase is short in comparison with the propagation interval in the remainder of the system and that the path average dispersion is anomalous.

Abstract: An optical fiber coiled cord having a coil construction in which an optical fiber cord is spirally bent to obtain lengthwise stretchability, wherein the fiber coiled cord is provided with a stretch length control member which restricts lengthwise elongation.

Abstract: An optical fiber includes a glass fiber having a glass core and a cladding that contains voids that are spaced apart from the core, in contact with the core, or form a substantial portion of the core. The voids act as trapping sites for ingressing molecules from the surrounding environment, thereby reducing the effect of such molecules on the fiber's light-transmission properties.

Abstract: It is disclosed a polymerizable composition for producing an optical member for 850 nm wavelength comprising: a polymerizable monomer composition and a compound, having a different refractive index from that of the polymerizable monomer composition, whose structure has a benzene ring substituted by a substituent having a Hammett value of not greater than 0.04 or by plural substituents having an average value of Hammett values thereof of not greater than 0.04. It is also disclosed a polymerizable composition for producing an optical member comprising a polymerizable monomer composition comprising at least one selected from the group consisting of C7-20 alicyclic (meth)acrylates and a compound, having a different refractive index from that of the polymerizable monomer composition and having a solubility parameter of not greater than 10.9, whose structure has a benzene ring substituted by the substituent or the substituents defined above.

Abstract: Optical waveguide fiber that is bend resistant and single mode at 1260 nm and at higher wavelengths. The optical fiber includes a core of radius R1 and cladding, the cladding having an annular inner region of radius R2, an annular ring region, and an annular outer region. The annular ring region starts at R2, and the ratio R1/R2 is greater than 0.40.

Abstract: A coupling waveguide is interconnected between a launching fiber and a receiving fiber to reduce coupling loss. The coupling waveguide includes an integrally formed graded index lens having a non-parabolic refractive index profile. The graded index lens receives as an input a coupling mode field of an optical signal launched by the launching fiber and transforms the coupling mode field into a transverse spatial distribution matching a corresponding coupling mode field of the receiving fiber.

Abstract: A microbend-induced fiber grating is formed from a section of optical fiber configured to exhibit “splitting” between the resonant wavelengths supported by the TE and TM components of the LP1m mode and the resonant wavelength supported by the odd/even HE2m components of the LP1m mode. Since only the TE and TM components are polarization dependent, by splitting and shifting the resonant wavelengths for these modes away from a system-desired wavelength(s) supported by the odd/even HE modes, a polarization insensitive microbend-induced fiber grating can be formed. A fiber core configuration including a central core region, trench and ring is formed to exhibit a large radial gradient in core refractive index profile, with a significantly steep transition between the ring index and the trench index, to provide the desired splitting between the (undesired, polarization sensitive) TE/TM modes and the HE mode.

Abstract: A microbend-induced fiber grating is formed from a section of optical fiber configured to exhibit “splitting” between the resonant wavelengths supported by the TE and TM components of the LP1m mode and the resonant wavelength supported by the odd/even HE2m components of the LP1m mode. Since only the TE and TM components are polarization dependent, by splitting and shifting the resonant wavelengths for these modes away from a system-desired wavelength(s) supported by the odd/even HE modes, a polarization insensitive microbend-induced fiber grating can be formed. A fiber core configuration including a central core region, trench and ring is formed to exhibit a large radial gradient in core refractive index profile, with a significantly steep transition between the ring index and the trench index, to provide the desired splitting between the (undesired, polarization sensitive) TE/TM modes and the HE mode.

Abstract: The invention relates to an optical component comprising at least one input monomode fiber (1-4), at least one output monomode fiber (5) and a diffractive element (7) which is disposed between the input fiber or fibers (1-4) and the output fiber or fibers (5). The inventive component is characterized in that at least one of the input or output fibers (1-5) comprises a fiber (1-5) containing a portion (21-25) which is designed to increase the radius of the mode field it guides. According to the invention, the portion which is designed to increase the mode field radius can comprise a portion with a graded index, a portion having a core or cladding refractive index which varies transversely and/or longitudinally.

Abstract: A method for producing a Bragg grating in an optical waveguide device such as an optical fiber. The optical fiber is exposed to a UV source through a phase mask and this produces a Bragg grating on the fiber. The grating on the fiber is overexposed such that the gratings are stronger than desired. The fiber is then annealed to stabilize the gratings left behind. The gratings left behind are still stronger than desired. The fiber is then exposed to a point source laser that reduces the index change for selected portions. This trims the existing grating to result in the desired grating strength.

Abstract: The invention relates to an chromatic dispersion-compensating optical fibre in the S-band, for use in compensating for the chromatic dispersion of either a standard SMF optical fiber or of an NZ-DSF optical fiber, carrying an optical signal in the spectral band in use, which is the S-band extending from 1460 nm to 1530 nm. The chromatic dispersion-compensating optical fiber in the S-band has a wavelength corresponding to the global chromatic dispersion minimum, which is situated outside the spectral band in use, that is to say outside the S-band.

Abstract: Even if a fiber fuse phenomenon occurs to start fire spreading, the fire spreading is shut off. A graded index fiber (GIF) 3 is inserted between transmission-use single mode fibers (SMF) 2a, 2b on a fiber optics transmission line 1. The GIF 3 is so designed that its mode field diameter (MFD) gradually increases from a light entry side. The MFD exhibits a maximum value at a location ¼ of a pitch from the end of the GIF 3. A GIF 3a is disposed on the light entry side. A GIF 3b having an MFD gradually decreasing is disposed on the opposite side of the GIF 3a. The GIF 3b is disposed on the light exit side. The lengths of the GIF 3a and GIF 3b are ¼ of a pitch. The length of the GIF 3 formed by connecting the both is ½ of a pitch. According to the present invention, an expanded MFD is inserted in the middle of the fiber optics transmission line, it is possible to shut off fire spreading caused due to fiber fuse phenomenon.

Abstract: The invention relates to the field of chromatic dispersion compensating optical fibers for a wavelength multiplexing transmission network. A chromatic dispersion compensating optical fiber is provided having at least six core slices (1 to 6) and having a negative chromatic dispersion and chromatic dispersion slope.

Abstract: A spiral wound fiber that includes birefringent interfaces is useful in different optical devices. One type of wound fiber includes at least first and second material layers. At least one of the layers is polymeric and at least one of the layers is birefringent. The spiral wound fiber may be used alone, or in an optical device. Such an optical device can include the fiber embedded within a matrix or attached to a substrate. The spiral wound fiber can be made by rolling a stack of at least two layers, by coextruding the two layers or by coating a rotating form.

Abstract: Provided is a method of manufacturing an optical fiber preform from which an optical fiber having the desired characteristics can easily be produced.

Abstract: A mirror structure includes a plurality of features of a defined size. The features include alternating spatial units of a chalcogenide glass and a thermoplastic polymer, and are specifically arranged in an ordered form so that the structure is highly reflective. Thermally-assisted methods are introduced for forming such structures.

Abstract: In general, in one aspect, the invention features a waveguide that includes a core extending along a waveguide axis and a confinement region surrounding the core. The confinement region includes a spiral portion and a non-spiral portion, wherein the spiral portion and the non-spiral portion extend along the waveguide axis.

Abstract: A graded-refractive-index optical fiber is fabricated by providing an elongated core rod of a first material including a concentration of high-refractive-index ions and a cladding tube of a second material including a lower concentration of the high-refractive-index ions present in the core rod material. The core rod is axially introduced into the cladding tube and the core rod and cladding tube are heated and vertically drawn in the furnace of a fiber drawing tower to cause the collapse of the cladding tube about the core rod and the radially outward diffusion of high-refractive-index ions into the cladding tube to yield an optical fiber exhibiting a radially graded refractive index that decreases with displacement from the rod axis. In various implementations, fused image-conducting fiber bundles are fabricated by bundling, heating and drawing a plurality of constituent-GRIN-optical-fiber pre-forms.

Abstract: Novel preforms and methods of making novel preforms are described. The preforms are suitable for being drawn into photonic bandgap optical fibres. In one form, the preform comprises a stack of elongate members having, in transverse cross section, a triangular close-packed arrangement of circular cross section capillaries, which define interstitial regions containing solid rods. The stack is supported around a relatively large capillary, which defines an inner region of the stack. The stack may be adapted by varying the number of rods in any given interstitial region, in order to generate various different configurations of cladding structure, which can be made into optical fibres having surprising operational characteristics, such as a split gap.

Abstract: A light source includes an LED die with an emitting surface and a collimating optical element. The optical element includes an input surface in optical contact with the LED emitting surface, and an output surface. The optical element has a first portion that comprises the input surface, made of a first optical material, and a second portion that comprises the output surface, made of a second optical material. The first optical material, which may include sapphire, diamond, or silicon carbide, has a higher refractive index, thermal conductivity, or both relative to the second optical material.

Abstract: An optical fiber for use in a metro network is provided. The optical fiber has a loss of 0.25 dB/km or less in the C-band and the L-band, a zero dispersion wavelength between 1560 nm and 1560 nm, and a dispersion slope of at least 0.074 ps/nm2/km at a wavelength of 1550 nm.

Abstract: An exemplary embodiment of the present invention includes an optical circulator. The circulator may have, for example, a first port, a second port, and a third port. The first port may be configured to introduce light into the optical circulator. The system may also include a tunable fiber filter Bragg grating connected to the second port of the circulator and a tunable dispersion-compensating fiber Bragg grating connected to the third port of the optical circulator. The tunable dispersion compensating fiber Bragg grating and the tunable fiber filter Bragg grating may be configured to be tuned by a single actuator. This tuning may be either compression or strain tuning.

Abstract: A photonic crystal fiber includes a core region for propagating light in a longitudinal direction of the fiber, a cladding region surrounding the core region, the cladding region including micro-structural elements extending in the longitudinal direction. The cladding region further includes at least one stress element having a coefficient of thermal expansion ?T,SAP and extending in the longitudinal direction of the photonic crystal fiber, the stress element(s) being located in a cladding background material having a coefficient of thermal expansion ?T,cladback different from ?T,SAP. The location of the at least one stress element relative to the core region and the micro-structural elements and the coefficients of thermal expansion ?T,SAP and ?T,cladback are adapted to provide a stress induced birefringence in the core region of the photonic crystal fiber. An article includes a photonic crystal fiber, a method of manufacturing and the use of a photonic crystal fiber are furthermore provided.

Abstract: The present invention relates to an optical fiber which has a structure for further increasing an FOM (=|dispersion|/loss) and which can be applied to a dispersion compensation module. The optical fiber is mainly composed of silica glass and has a core region including a center of an optical axis, a depressed region surrounding the core region, a ring region surrounding the depressed region, and a cladding region surrounding the ring region and doped with F. As compared with the refractive index of pure silica glass, a relative refractive index difference of the core region is 3% or more but 4% or less, a relative refractive index difference of the depressed region is ?1% or more but ?0.5% or less, a relative refractive index difference of the ring region is 0.01% or more but 0.24% or less, and a relative refractive index difference of the cladding region is ?0.3% or more but ?0.1% or less. The FOM at the wavelength of 1550 nm is 250 ps/nm/dB or more.

Abstract: Various types of holey fiber provide optical propagation. In various embodiments, for example, a large core holey fiber comprises a cladding region formed by large holes arranged in few layers. The number of layers or rows of holes about the large core can be used to coarse tune the leakage losses of the fundamental and higher modes of a signal, thereby allowing the non-fundamental modes to be substantially eliminated by leakage over a given length of fiber. Fine tuning of leakage losses can be performed by adjusting the hole dimension and/or the hole spacing to yield a desired operation with a desired leakage loss of the fundamental mode. Resulting holey fibers have a large hole dimension and spacing, and thus a large core, when compared to traditional fibers and conventional fibers that propagate a single mode. Other loss mechanisms, such as bend loss and modal spacing can be utilized for selected modes of operation of holey fibers. Other embodiments are also provided.

Abstract: A dispersion compensating optical fiber is disclosed having a high figure of merit. The optical fiber is highly dispersive and has low attenuation. The dispersion compensating optical fiber is suited for use with transmission optical fiber such as conventional single mode fiber. An optical transmission fiber and optical transmission system are also disclosed.

Abstract: The invention relates to the field of dispersion managed optical fibres for use in wavelength division multiplex transmission networks. A multimode optical fibre in which at least one higher-order mode can be propagated, is constituted radially by a single central core surrounded by an optical cladding (13), and comprises, for said higher mode or for at least one of said higher-order modes, positive chromatic dispersion optical fibre portions (D+) alternating longitudinally with negative chromatic dispersion optical fibre portions (D?).

Abstract: In general, in one aspect, the invention features an article including a high-power, low-loss fiber waveguide that includes alternating layers of different dielectric materials surrounding a core extending along a waveguide axis, the different dielectric materials including a polymer and a glass.

Abstract: The present invention provides a new and unique method for increasing the photosensitivity of a large diameter optical waveguide having a cross-section of at least about 0.3 millimeters. The method features loading the large diameter optical waveguide with a photosensitizing gas at a pressure at least about 4000 pounds per square inch (PSI) at a temperature of at least about 250° Celsius. The photosensitizing gas may be hydrogen, Deuterium or other suitable gas. The method also includes the step of using a particular large diameter optical waveguide having a core more than 1000 microns from the surface thereof. The method may be used as part of a process for writing a Bragg grating in an inner core or a cladding of the large diameter optical waveguide.