Provided is a method of processing a glass base material for optical fiber in which the glass base material for optical fiber is elongated to reduce a diameter thereof until reaching a final elongation diameter and form a completed base material. The method includes measuring an outer diameter distribution that includes an outer diameter of the glass base material for optical fiber; setting an effective region; calculating a target elongation diameter that is larger than the final elongation diameter and less than an average diameter of the effective region, and elongating the glass base material for optical fiber until reaching the target elongation diameter; and after reaching the target elongation diameter, further elongating the glass base material for optical fiber until reaching the final elongation diameter.

A hollow core photonic bandgap optical fibre comprises: a cladding comprising capillaries in a hexagonal array and a hollow core formed by excluding a hexagonal group of nineteen capillaries from the centre of the hexagonal array. The core is inflated. A core size ratio is 1.26 or above, defined as a ratio of the core diameter to the cladding diameter normalized to the ratio of the core diameter to the cladding diameter in an undistorted hexagonal array; a first ring ratio is between 0.55 and 2.50, defined as a ratio of the length of radially aligned struts separating the capillaries of the first ring to the length of a strut in an undistorted hexagonal array; and a core node spacing is between 0.60 and 1.90, where defined as a ratio of a strut length around the core of a largest corner capillary and a strut length around the core of a smallest side capillary. The fabrication method comprises four different pressures for the core, corner capillary, side capillary and cladding.

The vacuum-based methods of forming an optical fiber preform include applying a vacuum to a preform assembly. The preform assembly has at least one glass cladding section with one or more axial through holes, with one or more canes respectively residing in the one or more axial through holes. The opposite ends of the at least one glass cladding section are capped to define a substantially sealed internal chamber. A vacuum is applied to the substantially sealed internal chamber to define a vacuum-held preform assembly. The methods also include heating the vacuum-held preform assembly to just above the glass softening point to consolidate the vacuum-held preform to form the cane-based glass preform. An optical fiber is formed by drawing the cane-based glass preform. The same furnace used to consolidate the vacuum-held preform can be used to draw the optical fiber.

A multicore fiber according to an embodiment of the present invention includes a plurality of cores and a cladding that encloses the plurality of the cores. The external form of the cladding in a cross section is formed of an arc portion that is formed in an arc shape relative to the center axis of the cladding and a non-arc portion that is pinched between two ends of the arc portion and not formed in an arc shape relative to the center axis of the cladding. The non-arc portion is formed with a pair of projections projecting from two ends of the arc portion on the opposite side of the center axis relative to a straight line connecting the both ends of the arc portion and one or more of recesses pinched between the pair of the projections.

Methods are known for producing an anti-resonant hollow-core fiber which has a hollow core extending along a fiber longitudinal axis and an inner jacket region that surrounds the hollow core, said jacket region comprising multiple anti-resonant elements. The known methods have the steps of: providing a cladding tube that has a cladding tube inner bore and a cladding tube longitudinal axis along which a cladding tube wall extends that is delimited by an interior and an exterior; providing a number of tubular anti-resonant element preforms; arranging the anti-resonant element preforms at target positions of the interior of the cladding tube wall, thereby forming a primary preform which has a hollow core region and an inner jacket region; and elongating the primary preform in order to form the hollow-core fiber or further processing the primary preform in order to form a secondary preform. The aim of the invention is to achieve a high degree of precision and an exact positioning of the anti-resonant elements in a sufficiently stable and reproducible manner on the basis of the aforementioned methods. This is achieved in that a cladding tube is provided with an outer diameter ranging from 90 to 250 mm and a length of at least 1 m; tubular structural elements are provided, at least some of which have a wall thickness ranging from 0.2 to 2 mm and a length of at least 1 m; and the structural elements are arranged in the cladding tube inner bore while the cladding tube longitudinal axis is vertically oriented, the upper end face of each structural element being positioned at the target position.

Methods for preform and tube draw based on controlling forming zone viscosity determined by calculating a holding force exerted by the glass component in the forming zone on the strand being drawn below. The holding force may be calculated by determining a gravitational force applied to the strand and a pulling force applied to the strand by a pulling device, where the holding force is equal to the opposite of the algebraic sum of the gravitational and pulling forces. The holding force may also be calculated by measuring a stress-induced birefringence in the strand at a point between the forming zone and the pulling device, determining an amount of force applied to the strand at the point corresponding to the birefringence, and calculating the holding force by correcting the amount of force for a gravitational effect of the weight of the strand between the forming zone and the point.

The present invention, as disclosed and described herein, in one aspect thereof comprises a preform for making a vortex optical fiber includes a glass cylinder formed substantially of silicone dioxide that defines a core portion along a longitudinal axis of the glass cylinder and a cladding portion surrounding the core portion. The glass cylinder further defines a plurality of holes running parallel to the longitudinal axis from a first end of the glass cylinder to a second end of the glass cylinder.

A multicore fiber is provided. The multicore fiber includes a plurality of cores spaced apart from one another, and a cladding surrounding the plurality of cores and defining a substantially rectangular or cross-sectional shape having four corners. Each corner has a radius of curvature of less than 1000 microns. The multicore fiber may be drawn from a preform in a circular draw furnace in which a ratio of a maximum cross-sectional dimension of the preform to an inside diameter of the preform to an inside diameter of the draw furnace is greater than 0.60. The multicore fiber may have maxima reference surface.

A method of producing bi-modal particles includes the steps of igniting a first precursor gas using a primary burner thereby producing a first plurality of particles of a first size, fluidly transporting the first plurality of particles down a particle tube, igniting a second precursor gas using a secondary burner thereby producing a second plurality of particles of a second size, flowing the second plurality of particles into the first plurality of particles, and capturing the first and second plurality of particles.

An optogenetic probe, an optogenetic system, and a method for fabricating an optogenetic probe are provided. The optogenetic probe has a proximal and a distal end, and includes an elongated body made of a body glass material and extending longitudinally between the proximal and distal ends. The optogenetic probe also includes at least one optical channel, each including an optical channel glass material having a refractive index larger than a refractive index of the body glass material, so as to guide light therealong. The optogenetic probes also includes at least one electrical channel, each including an electrical channel structure having an electrical conductivity larger than the electrical conductivity of the body glass material, so as to conduct electricity therealong. The optogenetic probe further includes at least one fluidic channel, each adapted for transporting fluid therealong. Each optical, electrical and fluidic channel extends longitudinally within the elongated body.