Chirp-grating lens for guided-wave optics

Abstract

A high‐throughput diffraction‐limited chirp‐grating Bragg diffraction lens for guided‐wave optical device applications has been demonstrated with planar photolithographic fabrication techniques. Diffraction‐limited performance has been obtained with a 2‐mm‐aperture f/16 lens focusing the He‐Ne laser beam to a 6.1‐μm spot size. The grating diffraction efficiency to the focus is over 90%. This type of lens has predictable focusing properties which are insensitive to process variations, an important consideration for accurately aligned integrated optical systems.