Optical functional devices

摘要

An optical functional device 1 has a slab type two-dimensional photonic crystal layer 29. The layer 29 has a dielectric layer 4 and a plurality of lattice columns 5 each comprising dielectric pillars. A waveguide portion 6 is provided in the photonic crystal layer 29. A ground electrode 8 and a signal electrode 9 are formed on the dielectric layer 4 for applying a modulating voltage on light propagating in the waveguide portion 6. A layer 2 of a high dielectric constant is laminated on the dielectric layer 4. A low dielectric portion is formed direct under the waveguide portion 6 and the lattice columns 7a, 7B and 7C of at least first, second and third orders in distance with respect to said waveguide portion.