US 3,982,123 AGranted

Optical fiber power taps

AssigneeBell Telephone Laboratories, Incorporated

InventorsJames Emanuel Goell, Tingye Li, Willis Martin Muska

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Abstract

There is disclosed a variety of arrangements for tapping a portion of the signal power from an optical fiber waveguide without requiring that the fiber be terminated or broken. Power is coupled out of the fiber waveguide, which typically includes an inner core surrounded by a lower refractive index outer cladding, by disposing a dielectric body in a coupling relationship with an intermediate length of the fiber from which all or most of the cladding has been removed or, alternatively, which is bent to cause a portion of the power to radiate out of the inner core into the outer cladding of the fiber. The dielectric body couples power out of the fiber provided its index of refraction is approximately equal to, or greater than, that of the fiber cladding material. The power coupled out by the dielectric body is converted to a representative electrical signal by a photodetector disposed adjacent to the dielectric body.

Claims6

Dependent claims

An arrangement for tapping optical power from an intermediate portion of an optical fiber waveguide without requiring that the fiber be terminated or broken, said fiber including a guiding region in which the optical power is essentially confined, and including a medium surrounding said guiding region, said arrangement being characterized by:

a body of dielectric material disposed in a coupling relationship to an intermediate length of said fiber, said body having an index of refraction which is approximately equal to or greater than the index of refraction of the medium surrounding said guiding region of said fiber and is selected to couple only a minor portion of the optical power propagating in said fiber waveguide guiding region toward a surface of said dielectric body laterally offset from said guiding region;
a photodetector contacting said laterally offset surface of said dielectric body and including an active area responsive to the wavelength of the optical signal to be propagated through said fiber, said active area of said photodetector being oriented to intercept the optical power coupled out of said guiding region of said fiber by said dielectric body;
and
in which said guiding region of said fiber comprises an inner core formed of a low optical loss material, said medium surrounding the guiding region comprising an outer cladding of lower refractive index than that of said inner core;
and
said dielectric body has an index of refraction greater than about 0.8 times the index of refraction of said outer cladding of said fiber.

3 more elements

Dependencies are inferred from the claim text.