Incremental method of producing multiple UV-induced gratings on a single optical fiber

• US 6,272,886 B1
• Filed: 10/23/1996
• Issued: 08/14/2001
• Est. Priority Date: 10/23/1996
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Novack, James C., Singh, Harmeet, Cronk, Bryon J., Rabine, Bruce A., Sanders, Paul E., Ball, Gary A.
• Primary Examiner(s): HOFFMANN, JOHN M
• Application Number:
  US08/735,468
• Time in Patent Office: 1,756 Days
• Field of Search: 653/92, 654/25, 653/87, 430/290, 430/321
• US Class Current: 65/387
• CPC Class Codes: G02B 6/02123 characterised by the method of manufacture of the grating photolithography G03F7/0005
• CPC Class Codes: G02B 6/245 Removing protective coverings of light guides before coupling

Abstract

The present invention is a process for manufacturing an optical fiber Bragg grating, which in a preferred embodiment includes the steps of: (a) removing at least a portion of a removable coating on an optical fiber element in at least one predetermined section to sufficiently expose the optical fiber in the section for a subsequent treatment by a source of optical radiation; (b) fixing the at least one section with respect to the source of optical radiation; (c) directing optical radiation from the source into the optical fiber to produce at least one Bragg grating in the at least one section; and (d) covering the at least one section. The present invention also extends to an apparatus for carrying out the process steps described above, which includes means for coating removal, means for fiber immobilization, means for writing a Bragg grating, and means for packaging.

Claims

1. A continuous process of manufacturing a plurality of optical fiber Bragg gratings, which comprises the following steps:

(a) pulling a continuous length of a coated optical fiber having a thermally removable coating into an apparatus comprising a coating removal station, a grating writing station and a recoating station sequentially arranged in a process line;

(b) advancing the continuous length of the coated optical fiber through the apparatus until a first section of the coated optical fiber is in the coating removal station and exposing the first section to a heated gaseous stream to remove the thermally removable coating therefrom;

(c) advancing the optical fiber through the apparatus until the first section is in the grating writing station and a second section is in the coating removal station, wherein

(i) in the grating writing station, gripping a first end of the first section and a second end of the first section to immobilize the first section, and directing optical radiation into the optical fiber and writing at least one Bragg grating in the first section, and,

(ii) in the coating removal station, exposing the second section to a heated gaseous stream to remove the thermally removable coating therefrom;

(d) advancing the optical fiber through the apparatus until the first section is in the recoating station, the second section is in the grating writing station, and a third section is in the coating removal station, wherein

(i) in the recoating station, recoating the first section with a second coating different from the thermally removable coating, and

(ii) in the grating writing station, gripping a first end of the second section and a second end of the second section to immobilize the second section, and directing optical radiation into the optical fiber and writing at least one Bragg grating in the second section, and,

(iii) in the coating removal station, exposing the third section to a heated gaseous stream to remove the thermally removable coating therefrom; and

(e) continuously advancing the optical fiber through the apparatus until a desired number of Bragg gratings are written in the optical fiber.

2. An in-line continuous process of manufacturing a plurality of Bragg gratings, which comprises the following steps:

(a) providing a continuous length of coated optical fiber having a thermally removable coating;

(b) positioning a section of the continuous length of optical fiber at a coating removal station and thermally removing at least a portion of the thermally removable coating in the section of the continuous length of optical fiber to expose a generally bare portion of the optical fiber in the section;

(c) positioning the section of the continuous length of optical fiber element in a writing station and immobilizing the bare portion of optical fiber with respect to a source of radiation;

(d) directing radiation from the source into the bare portion of optical fiber and writing at least one Bragg grating;

(e) positioning the section of the continuous length of optical fiber at a recoating station and recoating the bare portion of optical fiber; and

(f) repeating steps (b)-(e) sequentially along different sections of the length of optical fiber as necessary to write a number of Bragg gratings in the optical fiber, wherein the different sections of the length of optical fiber are each positioned at one of the different stations.

3. An in-line continuous process of manufacturing a Bragg grating in an optical fiber, which comprises the following steps:

(a) providing a continuous length of optical fiber;

(b) positioning the length of optical fiber in a continuous process line, wherein the continuous length of optical fiber advances past a source of radiation;

(c) fixing at least one section of the optical fiber with respect to the source of radiation;

(d) directing radiation from the source into the optical fiber and writing at least one Bragg grating in the at least one section; and

(e) advancing a new section of the continuous length of optical fiber past the source of radiation and repeating steps (c) to (d).

4. A continuous process of manufacturing a plurality of optical fiber Bragg gratings comprising the steps of:

providing a length of a coated optical fiber having a thermally removable coating;

pulling the optical fiber in an in-line continuous grating writing apparatus, the apparatus including a payoff spool, a coating removal station, a grating writing station, a recoating station, and a take-up spool, wherein the optical fiber is stored in the payoff spool, advances sequentially past the coating removal station, the grating writing station, and the recoating station, and is spooled into the take-up spool;

advancing the coated optical fiber through the apparatus until a first section of the coated optical fiber is in the coating removal station;

exposing the first section to a heated gaseous stream to remove the thermally removable coating therefrom;

advancing the bare optical fiber through the apparatus until the first section is in the grating writing station;

writing at least one grating on the bare optical fiber in the first section;

advancing the bare optical fiber through the apparatus until the first section is in the recoating station;

applying a coating to the first section; and

spooling the first section into the take-up spool.

5. The process of claim 4, wherein the steps of advancing the optical fiber comprise spooling the optical fiber into the take-up spool in a step-wise motion.

6. A continuous process for manufacturing a plurality of optical fiber Bragg gratings which comprises the following steps:

(a) providing a continuous length of a coated optical fiber having a thermally removable coating;

(b) positioning the length of optical fiber in an in-line apparatus including a coating removal station and a grating writing station;

(c) positioning a section of the length of the coated optical fiber at the coating removal station and thermally removing at least a portion of the thermally removable coating in the section to expose a generally bare portion of optical fiber in the section;

(d) positioning the bare portion of optical fiber at the writing station and immobilizing the bare portion of optical fiber with respect to a source of radiation;

(e) directing radiation from the source into the bare portion of optical fiber and writing at least one Bragg grating in the bare portion of optical fiber; and

(f) recoating the bare portion of optical fiber,

wherein the steps of positioning the optical fiber comprise spooling the optical fiber element in a step-wise motion.