Systems and Methods for Reduced End-face Reflection Back-Coupling in Fiber-Optics


Vanderbilt researchers have developed a technology for suppressing end-face reflections in most fiber optic components, thereby reducing a significant source of noise in fiber-optic systems. The solution employs a fused-spliced length of angle-polished no-core fiber in order to angle reflections outside the acceptance numerical aperture of the fiber and spatially offsetting any reflections to minimize back-coupling. The result is a compact solution that significant decreases noise without significantly altering the specifications of the fiber-optic component.

Addressed Need

Fiber end-face back-reflection is a significant source of noise in fiber-optic systems. The reflection is a result of a refractive index discontinuity between the fiber core and either air another optical material at the interface between fiber-optic relays. While angled physical contact connectors address this problem for single-mode fibers, they do not perform nearly as well for multi-mode, double-clad, or high numerical aperture single-mode fibers. The present technology overcomes these limitations.

Unique Features

  • Significantly reduces noise caused by end-face back-reflection, notably in multi-mode and double-clad fibers
  • Compact solution that utilizes off-the-shelf components
  • Does not significantly change the specifications of the fiber-optic component

Technology Development Status

Several embodiments of the solution have been built and tested, resulting in significant noise reduction as shown in Figure 1.

Intellectual Property Status

A patent application has been filed.


Figure 1: Comparison of return losses from double-clad fibers. The blue line shows a flat-polished double-clad fiber without the Vanderbilt solution, whereas the orange and yellow line show different configurations of the Vanderbilt technology, resulting in a -25 and -30 dB reduction in return loss.

Licensing Contact

Philip Swaney

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