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Abstract

A compact optical waveguide employs a photonic band gap element as a reflector to enable a light beam to be reflected at angles greater than the critical angle. The photonic band gap device is a two-dimensional array of columnar holes formed in the substrate the holes are filled with air or another material having a different dielectric constant than the substrate. The optical waveguide forms a right angle bend and first and second photonic band gap devices are formed on both the inside and outside angles of the bend to deflect light which is incident on the waveguide at an angle greater than a critical angle defined by the materials that constitute the optical waveguide. The columnar holes of the photonic band gap element have a diameter of approximately one-half wavelength and are arranged in a triangular packing having an inter-column separation of approximately one-half wavelength of the light which is to be transmitted through the waveguide. The optical waveguide is formed by depositing a transmissive material having a first refractive index on top of a substrate which has a second refractive index and, using an ultrafast laser, cutting channels into the transmissive material to define straight portions of the waveguide and, also using the ultrafast laser, cutting the columns into the transmissive material to define the photonic band gap elements. In another example of the invention, the optical waveguide is formed by depositing a transmissive material having a first refractive index into a channel in a substrate which has a second refractive index and, using an ultrafast laser to cut the columns into the transmissive material to form the photonic band gap elements. In a final example of the invention, the optical waveguide is formed by depositing a transmissive material having a first refractive index which forms a channel on top of a substrate which has a second refractive index and, using an ultrafast laser to cut the columns into the transmissive material to form the photonic band gap elements.

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First Claim