Polymer optical fibre for active implantable medical devices (AIMD) and AIMD using same

A polymer optical fibre (POF) (30) for transmitting light of a wavelength, λi, between two separate elements of an active implantable medical device (AIMD), wherein the wavelength, λi, is between 380 and 1800 nm and wherein said POF is a multimode optical fibre comprising a first end and a second end, and comprises:

• (a) a core (31) which is cylindrical and made of a cyclic olefin polymer (COP) or copolymer (COC), having a core refractive index n_core at the wavelength, λi, the core being enclosed in
• (b) a cladding (32) which has a cladding refractive index n_clad<n_core at the wavelength and which is made of a cladding copolymer comprising monomers of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, the cladding being itself enclosed in
• (c) a coating (33) which is made of a coating polymer comprising one of the monomers of the cladding copolymer, and wherein the coating polymer has a higher stiffness than the cladding copolymer,
• wherein the POF has a numerical aperture, NA, at the wavelength, λi, of at least 0.5, wherein NA=((n_core)2-(n_clad)2)1/2.