Optical fiber coupler with tunable coupling ratio and method of making
US4763977A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 9, 1985 |
| Grant date | Aug 16, 1988 |
| Priority date | — |
| Expiry date | Jan 9, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S359/90
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical coupler for single mode optical signals having a tunable (variable) coupling ratio, and a method of fabricating the coupler. A pair of virtually identical optical fibers are fused together at a narrowed waist region, each fiber being formed of a core and cladding, each being tapered toward the waist in such a manner as to ensure adiabatic propagation of light in the structure. An optical signal carried by one fiber first passes through a decreasing taper region and then passes through an increasing taper region of one or the other fiber (or both). The decreasing taper rate of the input portion of one fiber is such that the optical signal radiates out of the core (where V=1 locally) and into the cladding, as it approaches the waist. The increasing taper rates of the output portions of the two fibers are such that a predetermined coupling ratio is obtained. The coupler is bent in the region of the waist whereby a coupling ratio can be selected between the incoming fiber portions having the decreasing taper and the outgoing fibers having increasing tapers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.