It has been demonstrated by many researchers that smooth void dots and void channels have been generated efficiently in polymers and glasses by use of a femtosecond laser induced microexplosion method. This method has been used to fabricate three-dimensional (3D) photonic crystals in those media. But the low refractive index media cannot open 3D complete bandgaps. Lithium niobate (LiNbO3 ) has a high refractive index of ~2.2 and a large transparent range of 0.45-5 µm which makes it a suitable candidate for near-infrared photonic crystal fabrication. As LiNbO3 has large nonlinear coefficients, photonic crystals made from it may have strong nonlinearity and therefore functionality. In this talk, I will report on our recent work on the fabrication of 3D photonic crystals in a bulk LiNbO3 crystal by using the femtosecond laser-induced microexplosion method. In particular, the effect of the anisotropy of LiNbO3 and the large refractive-index mismatch between LiNbO3 and its immersion medium on void generation will be discussed. The stop gaps of 3D photonic crystals consisting of a face-centred cubic lattice will be demonstrated.
Proceedings of the 3rd Pacific International Conference on Applications of Lasers and Optics (PICALO 2008), Beijing, China, 16-18 April 2008