US 2009/0154512 A1 · Method And Device For Monitoring Light

Abstract

A method for monitoring laser light launched into a core of a single mode fiber includes launching a portion of light directly into the cladding about the core. The cladding launched light is a known fraction of the core launched light and can be monitored by placing a detector about the cladding. Detected light including light that was launched into the cladding and has leaked through the cladding is used as a known fraction of light in the core and can be used to control the laser light source. This can be done with a straight section of single mode optical fiber and does not require bending the fiber. Advantageously, most of the core launched light remains in the core as guided light.

Claims11

Dependent claims

A method of monitoring light comprising:

a) launching a beam of light into an end of a single mode optical fiber having a core having a refractive index n1 and having a cladding surrounding the core, having a refractive index n2, wherein n1>n2, wherein a first portion P1 of the beam launched into the end of the single mode fiber is launched into the core at a first end face of the optical fiber, and wherein a second portion P2 of the beam of light is launched directly into the cladding at the first end face of the optical fiber, and wherein P2/P1>0.05;
and, detecting along a side of the optical fiber adjacent the cladding at a first location near the end of the fiber with a photodetector disposed along side of the fiber, a portion of light P3 that was launched into the fiber, wherein the portion of light includes more than 0.5% of P2 and no more than 0.003% of P1.

Dependencies are inferred from the claim text.

Method And Device For Monitoring Light

Life of this patent

Method And Device For Monitoring Light

Life of this patent

Abstract

Claims11