Femtosecond-laser micromachined optical waveguides in Bi4Ge3O12 crystals

The optical waveguides in Bi4Ge3O12 (BGO) crystals in both depressed-cladding and dual-line configurations have been produced using femtosecond-laser micromachining. The guiding properties and thermal stabilities of the BGO waveguides have been investigated for both geometries, showing different performance of the fabricated structures. Both depressed-cladding and dual-line waveguides support guidance along both TE and TM polarizations. Thermal annealing treatments up to 600 degrees C reduce the propagation loss of dual-line waveguides to as low as 0.5 dB/cm, while the cladding waveguide is only stable under thermal treatment not higher than 260 degrees C, reaching a propagation loss of 2.1 dB/cm. (C) 2013 Optical Society of America