Diffraction-limited geodesic lens for integrated optic circuit

Experimental and theoretical results are presented for aberration-free (except field curvatuve) geodesic lenses. A technique of calculating the aspherical lens profile with a rounded edge is summarized. A smooth transition at the lens edge is necessary to prevent undesirable scattering between the planar guide and the guide in the lens depression. Aberration-free lenses with diffraction-limited performance have been fabricated in both glass and LiNbO
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substrates. The experimental results indicate lens performance, other than the change of focal length, is not severely affected by the profile deviation resulting from lens fabrication. This is further supported by the profile tolerance analysis described in the paper.