It is well known that a fiber taper—an optical fiber whose size varies along its length—must exceed a certain minimum length to be adiabatic and low-loss. In contrast, we show that an optical fiber with a logarithmic refractive index profile can be adiabatically tapered over any length, however short. Its mode field distribution is independent of the fiber’s size and so remains the same along a taper. We report an experimental fiber in which tapers shorter than 2 mm can have losses as low as 0.03 dB. The fiber is compatible with standard telecoms fiber but with low bend loss and should have applications where it is desirable to make tapered fiber components (such as fused couplers and photonic lanterns) as short as possible. The index profile is analogous to the logarithmic potential of quantum mechanics.
- Fiber design and fabrication
- Fiber optics components
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics