Ultrahigh transmission optical nanofibers

Abstract

We present a procedure for reproducibly fabricating ultrahigh transmission optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode transmissions of 99.95 ± 0.02 %, which represents a loss from tapering of 2.6 × 10 −5 dB/mm when normalized to the entire stretch. When controllably launching the next family of higher-order modes on a fiber with 195 mm stretch, we achieve a transmission of 97.8 ± 2.8%, which has a loss from tapering of 5.0 × 10 −4 dB/mm when normalized to the entire stretch. Our pulling and transfer procedures allow us to fabricate optical nanofibers that transmit more than 400 mW in high vacuum conditions. These results, published as parameters in our previous work, present an improvement of two orders of magnitude less loss for the fundamental mode and an increase in transmission of more than 300% for higher-order modes, when following the protocols detailed in this paper. We extract from the transmission during the pull, the only reported spectrogram of a fundamental mode launch that does not include excitation to asymmetric modes; in stark contrast to a pull in which our cleaning protocol is not followed. These results depend critically on the pre-pull cleanliness and when properly following our pulling protocols are in excellent agreement with simulations.

Optical Nanofibers

“…A CO 2 laser produces high-transmission optical nanofibers but the final diameter is limited by the power and focus of the laser. Our work Hoffman et al (2014) follows closely that of Warken (2007) and we summarize it in this section.…”

“…If any particulate remains from the fiber buffer or if dust arrives on the fiber before being introduced to the flame, the particulate will burn and greatly diminish the final transmission, see Hoffman et al (2014). Residue from solvents can also decrease transmission.…”

“…Following the protocols described in this section we have produced fibers with 99.95% transmission when launching the fundamental mode Hoffman et al (2014). This high transmission corresponds to a loss of 2.6 × 10 −5 dB/mm for the fundamental mode Brambilla (2010); Stiebeiner et al (2010), with controllable taper geometries and long fiber waists.…”

“…The glass malleability ensures low surface roughness. The smoothness of the surface is a great asset since it leads to ultra-high transmission structures that can withstand high optical powers (almost one Watt in vacuum Hoffman et al (2014)) without permanent damage to the fiber or degradation of the transmission.…”

“…Nanofibers can be produced in-house, using a heat-and-pull method Hoffman et al (2014); Ward et al (2014). The glass malleability ensures low surface roughness.…”