An Integrated Optic Approach to 10μm LIDAR

The paper describes a novel integrated optics approach to coherent 10.6μm LIDAR systems. The concept is based on using hollow waveguides to guide light between components located in a common dielectric substrate. The concept, referred to as Hollow Waveguide Integrated Optics (HOW-IO), has advantages in relation to achieving and maintaining good coherent mixing efficiencies and has the potential to: reduce size, increase ruggedness and lower manufacturing costs. The figure shows a plan view photograph of a HOW-IO interferometer subsystem which we have realised in practice. The integrated components and interconnecting waveguides are clearly visible. The subsystem was formed in a 180×190×20mm polycrystalline alumina substrate using a computer controlled milling machine. Polycrystalline alumina was chosen as the substrate and lid material because its optical properties, in conjunction with waveguides of appropriate cross section, allow the realisation of low attenuation coefficients at 10.6μm.