Subwavelength-diameter optical fibre

Due to such a strong geometrical confinement, the guided electromagnetic field in an SDF is restricted to a single mode called fundamental.

[1] There is no general agreement on how these optical elements are to be named; different groups prefer to emphasize different properties of such fibres, sometimes even using different terms.

[12] All the names with the prefix nano- are somewhat misleading, since it is usually applied to objects with dimensions on the scale of nanometers (e.g., nanoparticle, nanotechnology).

For this purpose, a laser beam is coupled to the fibre being pulled and the output light is monitored by an optical power meter throughout the whole process.

A good-quality SDF would transmit over 95% of the coupled light,[30] most losses being due to scattering on the surface imperfections or impurities at the waist region.

If the fibre being tapered is uniformly pulled over a stationary heating source, the resulting SDF has an exponential radius profile.

If significant laser power is coupled into the fibre, the dust particles will scatter light in the evanescent field, heat up, and may thermally destroy the waist.

[40][41] Subwavelength-diameter optical fibers have various applications owing to the special conditions of confining light in nanoscale dimensions.