Fibre gratings written through the coating at 244 nm and 248 nm

Fibre Bragg gratings have been written through the fibre coating using 244 nm frequency-doubled Ar⁺-ion 248 nm KrF excimer lasers for the first time. A standard off-the-shelf coating was used, and 92% reflectivity gratings were obtained with an index change of 2.4×10⁴