Photonic crystal waveguide and directional coupler using the same

A photonic crystal waveguide comprising:

• a substrate;
• a bottom cladding layer over said substrate;
• and
• a core layer with a uniform thickness over said bottom cladding layer, said core layer having a uniform distribution of holes;
• wherein said core layer has at least a waveguide region, on which a dielectric pattern is provided which has a refractive index higher than a substance in contact with a top surface of said core layer.

A photonic crystal waveguide comprising:

• a substrate;
• a bottom cladding layer over said substrate;
• and
• a core layer with a uniform thickness over said bottom cladding layer, said core layer having a uniform distribution of holes;
• wherein said core layer has at least a waveguide region, and said holes except on said waveguide region are filled with an air, whilst said holes on said waveguide regions are filled with a filler material having a refractive index higher than 1.

A directional coupler comprising:

• a substrate;
• a bottom cladding layer over said substrate;
• and
• a photonic crystal core layer over said bottom cladding layer, said core layer having a uniform distribution of holes, and said core layer being made of such a photonic crystal material that a wavelength of a light to be propagated through said waveguide region is in the vicinity of a photonic band gap edge of said photonic crystal material in order to utilize an intense dispersion phenomenon;
• and said core layer having a pair of stripe-shaped waveguide regions which extends in parallel to each other,
• wherein said stripe-shaped waveguide regions are thicker than a remaining region of said core layer to cause a refractive index guide effect.

A directional coupler comprising:

• a substrate;
• a bottom cladding layer over said substrate;
• and
• a photonic crystal core layer over said bottom cladding layer, said core layer having a uniform distribution of holes, and said core layer being made of such a photonic crystal material that a wavelength of a light to be propagated through said waveguide region is in the vicinity of a photonic band gap edge of said photonic crystal material in order to utilize an intense dispersion phenomenon;
• and said core layer having a pair of stripe-shaped waveguide regions which extends in parallel to each other,
• wherein dielectric patterns is provided on said waveguide regions, and said dielectric patterns have a refractive index higher than a substance in contact with a top surface of said core layer.

A directional coupler comprising:

• a substrate;
• a bottom cladding layer over said substrate;
• and
• a photonic crystal core layer over said bottom cladding layer, said core layer having a uniform distribution of holes, and said core layer being made of such a photonic crystal material that a wavelength of a light to be propagated through said waveguide region is in the vicinity of a photonic band gap edge of said photonic crystal material in order to utilize an intense dispersion phenomenon;
• and said core layer having a pair of stripe-shaped waveguide regions which extends in parallel to each other,
• wherein said core layer has at least a waveguide region, and said holes except on said waveguide region are filled with an air, whilst said holes on said waveguide regions are filled with a filler material having a refractive index higher than 1.