Presently, there is no truly flexible delivery system for light from Er:Yag medical lasers (λ = 2.94 μm) which allows
surgeons to work unrestricted. Instead, either a relatively inflexible articulated arm or multi-mode fibre, limited to large
bend radii, must be used. One proposed solution is the use of novel types of hollow core - band gap optical fibre rather
than more traditional large area solid core fibres. In these silica based fibres, material absorption and damage limitations
are overcome by using a photonic band gap structure. This confines radiation to lower order modes, that are guided in a
small diameter air core. The overall fibre diameter is also smaller, which allows a smaller mechanical bend radius.
Together with the guidance in air, this improves the laser power damage threshold. However, there are many practical
hurdles that must be overcome to achieve a robust system for use in surgery.
One of the main problems is that the fibre structure is hollow and ingress of dust, vapour, fluids and other contaminants
need to be prevented to ensure safe in-vivo usage. Additionally, any infibre contamination will degrade the laser damage
resistance of the fibre leading to potential catastrophic failure. The development of a robust and hermetically sealed end
cap for the fibre, without adversely affecting beam quality or damage threshold is an essential prerequisite for the safe
and efficient use of such fibres in surgery. In this paper we report on the progress on implementing end caps and describe
novel methods of sealing off these hollow fibres in particular for surgical applications. This work will demonstrate that
the use of these superior fibres with low loss guidance at 2.94 μm in surgery is feasible.