Abstract: The disclosure provides a method of functionalising sodium carboxy methylcellulose (Na-CMC) which is a cellulose comprising at least one unit of Formula (0), where at least one G0 group is (I) and the remaining G0 groups are H. The disclosure also provides a CMC derivative product obtainable by this method, wherein the CMC derivative product comprises at least one unit of Formula (3), wherein: L is (II), n is an integer from 0 to 450; X is selected from (III), (IV), (V), (VI), (VII), (VIII), and (IX); L1 is a bond, alkylene, -(alkylene)O—*, —O(alkylene)-*, or -(alkylene)C(O)—*; wherein the*is the attachment to the cyclooctene or benzene ring; Z is —F, —Cl, —Br, or —I; R2 is —L2-M; L2 is an alkylene, -(alkylene)C(O)—*, -(alkylene)NHC(O)—*, —(CH2CH2O)mCH2—*, —CH2(OCH2CH2)m—*, arylene, or a bond, wherein the*is the attachment to M and m is an integer between 1 to 450; and M is a biomolecular unit.

Abstract: There is provided an optical fiber for providing increased sensitivity in sensing applications by increasing the Rayleigh backscatter coefficient of the fiber while maintaining tolerable levels of signal attenuation (e.g., less than 20% over 10 km). Such an optical fiber comprises a core, a first cladding layer and a second cladding layer. The core comprises at least one core dopant selected from the range of: germanium, phosphorus, aluminium, boron, fluorine. The at least one core dopant is used to increase the core refractive index and enhance the core Rayleigh backscatter coefficient. The first cladding layer comprises at least one dopant selected from: germanium, phosphorus, aluminium, boron, fluorine; wherein at least one first cladding layer dopant is used to reduce the first cladding layer refractive index. The signal attenuation generated in the fiber is less than 20% over 1 km.

Abstract: A method of producing a planar substrate having waveguide channels, which method comprises: (i) providing a tube (6) of a substrate material; (ii) depositing silica layers (110) on the inside of the tube (6), the silica layers (110) being doped with a photosensitive material; (iii) drawing the tube (6) so that the cross-sectional size of the tube (109) is reduced; (iv) before or after the reducing of the cross-sectional size of the tube (6), causing the tube (6) to collapse into a flat shape by applying a low pressure to the tube, whereby the deposited silica layers together form a photosensitive silica layer (111); (v) cutting to required lengths the tube (6) which has been collapsed and reduced in cross-sectional size; and (vi) using laser writing to define waveguide channels in the cut lengths of the tube (6) and thereby to produce the planar substrate having the waveguide channels.

Abstract: A method of producing a planar substrate having waveguide channels, which method comprises: (i) providing a tube (6) of a substrate material; (ii) depositing silica layers (110) on the inside of the tube (6), the silica layers (110) being doped with a photosensitive material; (iii) drawing the tube (6) so that the cross-sectional size of the tube (109) is reduced; (iv) before or after the reducing of the cross-sectional size of the tube (6), causing the tube (6) to collapse into a flat shape by applying a low pressure to the tube, whereby the deposited silica layers together form a photosensitive silica layer (111); (v) cutting to required lengths the tube (6) which has been collapsed and reduced in cross-sectional size; and (vi) using laser writing to define waveguide channels in the cut lengths of the tube (6) and thereby to produce the planar substrate having the waveguide channels.