Nanoplasmonic filters for hollow core photonic crystal fibres

We demonstrate a method to add photonic functionalities to the tip of hollow photonic crystal bres, for ultra-compact and integrated lab-on-bre applications. Specifically we present an angularly robust passband lter that is directly applied to the facet of a bre, without adhesive or etching. The lter exploits the engineered plasmonic response of metallic features realised on a polymeric membrane and works over a range of 10 degrees, with a passband of 50 nm, centred at a wavelength of 800 nm. This result extends the available functionalities oered by the lab-on-bre methodology to photonic crystal bres, as well as providing a reversible method of functionalizing any type of bre.