Method and apparatus for sensing light

• US 20060165343A1
• Filed: 12/13/2005
• Published: 07/27/2006
• Est. Priority Date: 12/13/2004
• Status: Active Grant

• Current Assignee: Nufern Incorporated (Coherent Corp.)
• Original Assignee: Nufern Incorporated (Coherent Corp.)
• Inventors: Seifert, Martin
• Granted Patent: US 7,371,019 B2
• Time in Patent Office: Days
• US Class Current: 385/12
• CPC Class Codes: G01M 11/37 in which light is projected perpendicularly to the axis of the fibre or waveguide for monitoring a section thereof
• CPC Class Codes: G02B 6/02085 characterised by the grating profile, e.g. chirped, apodised, tilted, helical
• CPC Class Codes: G02B 6/2551 using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch
• CPC Class Codes: G02B 6/2804 forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
• CPC Class Codes: H01S 3/06704 Housings; Packages
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/1312 by controlling the optical pumping

Abstract

Disclosed is an optical apparatus including an optical fiber having a wavelength of operation, the optical fiber comprising a first length of the optical fiber joined to a second length of the optical fiber with a splice such that the first and second lengths are in optical communication; a photodetector for sensing light leaking from the splice; and wherein the splice has a splice loss of not greater than 0.5 dB at the wavelength of operation. Methods of sensing light are also disclosed.

Claims

1. Optical apparatus, comprising:

an optical fiber having a wavelength of operation, said optical fiber comprising a first length of the optical fiber joined to a second length of the optical fiber with a splice such that the first and second lengths are in optical communication;

a photodetector for sensing light leaking from said splice; and

wherein said splice has a splice loss of not greater than 0.5 dB at the wavelength of operation.

2. The optical apparatus of claim 1 wherein said photodetector comprises one of a phototransistor and a photodiode.

3. The optical apparatus of claim 1 wherein said photodetector is responsive to light having a wavelength from 900 to 1020 nm.

4. The optical apparatus of claim 1 wherein said splice is a fusion splice.

5. The optical apparatus of claim 1 wherein said first length of fiber is a double clad fiber having an inner cladding capable of propagating pump light having a first wavelength for pumping an active material for providing light having a second wavelength that is different than the first wavelength, and wherein said photodetector primarily senses either the pump light rather than light having the second wavelength or primarily senses the light having the second wavelength rather than the pump light, the wavelength of operation comprising one of the first and second wavelengths.

6. The optical apparatus of claim 5 wherein said photodetector primarily senses the light having the second wavelength rather than the pump light having the first wavelength.

7. The optical apparatus of claim 5 wherein said photodetector primarily senses the pump light having the first wavelength rather than the light having the second wavelength.

8. The optical apparatus of claim 1 wherein said optical fiber comprises a rare earth for providing light having a second wavelength responsive to receiving pump light having a first wavelength that is different than the second wavelength, the operating wavelength comprising one of the first and second wavelengths.

9. The optical apparatus of claim 8 comprising at least one pump light source for providing the pump light.

10. The optical apparatus of claim 8 comprising at least one reflective element for forming at least part of a laser resonator.

11. The optical apparatus of claim 1 wherein said splice loss is not greater than 0.25 dB.

12. The optical apparatus of claim 1 wherein said splice loss is not greater than 0.1 dB.

13. The optical apparatus of claim 1, comprising:

a body having a longitudinal passage therethrough, said passage receiving said splice, said body further comprising at least one surface receiving said photodetector such that the light leaking from said fiber splice can be received for sensing by said photodetector.

14. The optical apparatus of claim 13 wherein said surface includes an aperture for communicating the light leaking from said splice to said photodetector.

15. The optical apparatus of claim 13 comprising a material having a thermal conductivity of greater than 50 W/m K and wherein said splice comprises an outer surface contacting said material.

16. The optical apparatus of claim 15 wherein said outer surface is the outer surface of a glass region.

17. The optical apparatus of claim 15 wherein said body comprises said material.

18. The optical apparatus of claim 1 comprising a material having a thermal conductivity of greater than 50 W/m K and wherein said splice comprises an outer surface contacting said material.

19. A method for sensing light, comprising:

providing a first length of optical fiber having a wavelength of operation;

providing a second length of optical fiber having the wavelength of operation;

fusion splicing said first and second lengths of optical fiber so as to provide optical communication therebetween, said splice having a splice loss at the wavelength of operation of less than 0.5 dB;

providing a photodetector; and

sensing light leaking from said splice with said photodetector.

20. The method of claim 19 wherein providing the first length of fiber comprises providing a double clad fiber having an inner cladding capable of propagating pump light having a first wavelength for pumping an active material having a second wavelength different than the first wavelength, and wherein sensing light comprises primarily sensing either pump light rather than light having the second wavelength or primarily sensing light having the second wavelength rather than pump light, the wavelength of operation comprising one of the first and second wavelengths.