# US 2014/0153865 A1 · Optical fiber sensors having long active lengths, systems, and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153865 A1 - Document ID: US20140153865A1 - Status: Published application - Kind: A1 - Application number: 14/172,486 - Filed: 2014-02-04 - Published: 2014-06-05 - Earliest claimed: 2011-03-11 - Assignees: University of Maribor - Applicants: University of Maribor - Inventors: Denis Donlagic; Simon Pevec; Edvard Cibula - Web page: https://patentgrep.com/patent/US20140153865A1 ## CPC - C03B 37/14: Re-forming fibres or filaments, {i.e. changing their shape}(C03B37/025 takes precedence) - G01D 5/35312: {using a Fabry Perot} - G01B 1/00: Measuring instruments characterised by the selection of material therefor - G01B 11/18: {using photoelastic elements} - G01D 5/268: {using optical fibres (G01D5/28 - G01D5/38 take precedence)} - G01L 1/242: {the material being an optical fibre} - G01L 11/025: {using a pressure-sensitive optical fibre} - G01B 2290/25: Fabry-Perot in interferometer, e.g. etalon, cavity - C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract Optical fiber sensors adapted to measure strain or pressure are disclosed. The optical fiber sensor has a lead-in optical fiber having an end surface at a forward end, and a first optical element having a body with an outer dimension, Do, a front end surface coupled to the lead-in optical fiber, a pedestal including a retracted surface that is spaced from the front end surface, the retracted surface at least partially defining an optical cavity, a gutter surrounding the pedestal, the gutter having a gutter depth defining an active region of length, L, the first optical element further exhibiting L/Do≧0.5. Also provided are systems including the optical fiber sensor, and methods for manufacturing and using the optical fiber sensor. Numerous other aspects are provided. ## Claims ### Claim 1 A method of manufacturing an optical fiber sensor, comprising: providing a structure-forming fiber; and micromachining the structure-forming fiber to produce an outer dimension Do, a pedestal, and a gutter surrounding the pedestal having a gutter depth defining an active region of length, L, wherein L/Do≧0.5. ### Claim 2 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1, wherein L/Do≧1.0. ### Claim 3 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1, wherein L/Do≧1.5. ### Claim 4 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1, wherein L/Do≧2.0. ### Claim 5 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1, wherein a material micromachined to form the gutter comprises P2O5-doped silica. ### Claim 6 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1, wherein the structure-forming fiber includes: P2O5-doped silica in an axial region adjacent to the gutter-forming region; doped silica in the pedestal-forming region having a refractive index increasing dopant; and substantially pure silica in an outer annulus of the structure-forming fiber. ### Claim 7 (depends on 1) A method of manufacturing the optical fiber sensor according to claim 1 further comprising forming a tail portion that extends beyond a forward end of the gutter by a distance greater than Do/2. ### Claim 8 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1 further comprising forming a tail portion that extends beyond a forward end of the gutter by a distance greater than Do. ### Claim 9 (depends on 17) A method of manufacturing an optical fiber sensor according to claim 17 further comprising forming a tail portion that extends beyond the forward end of the gutter by a distance greater than or equal to 5 Do. ### Claim 10 (depends on 1) A method of manufacturing an optical fiber sensor according to claim 1 wherein the gutter is formed from a material comprising micro-capillaries or nano-capillaries. ### Claim 11 (depends on 1) An optical fiber sensor formed by the process of claim 1. ### Claim 12 A method of manufacturing an optical fiber sensor, comprising: providing a structure-forming fiber having a central portion etchable at a first rate when exposed to an etching medium, an inner cladding portion surrounding the central portion having an etching rate that is greater than the etching rate of the central portion when exposed to the etching medium, and an annular outer cladding portion surrounding the inner cladding portion having an etching rate that is less than the etching rate of both the central portion and the inner cladding portion when exposed to the etching medium; and exposing an end of the structure-forming fiber to the etching medium for a sufficient time to produce an outer dimension Do, a pedestal, and a gutter surrounding the pedestal having a gutter depth defining an active region of length, L, wherein L/Do≧0.5. ### Claim 13 (depends on 12) A method of manufacturing an optical fiber sensor according to claim 12, wherein: the central portion of the structure-forming fiber comprises doped silica having a refractive index increasing dopant; the inner cladding portion comprises P2O5-doped silica; the outer cladding comprises substantially pure silica. ### Claim 14 (depends on 12) A method of manufacturing an optical fiber sensor according to claim 12, wherein the inner cladding portion comprises capillaries. ### Claim 15 (depends on 12) An optical fiber sensor formed by the process of claim 12. ### Claim 16 A method of manufacturing an optical fiber sensor, comprising: providing a structure-forming fiber having a central portion having a composition of doped silica, an annular inner cladding portion surrounding the central portion having a composition of doped silica that is preferentially doped to provide an etching rate in an etching medium greater than the central portion, and an outer annulus portion surrounding the gutter portion and having a composition of substantially pure silica to provide an etching rate in the etching medium less than both the central portion and the annular inner cladding portion; and exposing an end of the first optical fiber segment to an etchant for a sufficient time to produce an outer dimension Do, pedestal, and a gutter surrounding the pedestal having a gutter depth defining an active region of length, L, wherein L/Do≧0.5. ### Claim 17 (depends on 16) A method of manufacturing an optical fiber sensor according to claim 16, wherein L/Do≧2.0. ### Claim 18 (depends on 16) A method of manufacturing an optical fiber sensor according to claim 16 further comprising forming a tail portion that extends beyond a forward end of the gutter by a distance greater than Do. ### Claim 19 (depends on 16) A method of manufacturing an optical fiber sensor according to claim 16, wherein the annular inner cladding portion comprises capillaries. ### Claim 20 (depends on 6) An optical fiber sensor formed by the process of claim 6.