Silica hollow core microstructured fibres for mid-infrared surgical applications

•All silica fibres developed for guiding at 2.94 μm with low loss (0.06 dB/m).•Bend insensitivity allows flexible delivery of high energy Er:YAG laser radiation.•Demonstration of hard tissue ablation in air and aqueous environments•Fibres may enable new minimally invasive surgical procedures.

In this paper two silica hollow core microstructured fibres (Negative Curvature Fibre and Photonic Bandgap Fibre) are presented with attenuations of 0.06 dB/m and 1.1 dB/m at 2.94 μm wavelengths, respectively. This is an important regime for medical applications, specifically surgery due to the existence of a strong absorption peak for water around 3 μm. The guidance of high energy pulses of the order of 195 mJ and 14.4 mJ respectively has been demonstrated. These energies are sufficient to ablate soft and hard biological tissues. As verification porcine bone was ablated in air and submerged in water to simulate practical application of a surgical device. These fibres open the way to a new and fully flexible delivery system for high energy Er:YAG laser radiation.