Multilevel-grating array generators: fabrication error analysis and experiments

The effects of mask alignment and etch-depth errors in the array uniformity error U and diffraction efficiency eta of multilevel-grating array illuminators are evaluated numerically. Also demonstrated are 16-level fan-out elements with array size up to 32 x 16, with U = 5%-10% and eta = 83%-92%. These are fabricated with electron-beam-written binary masks, optical alignment and contact copying, and reactive ion etching. Good-agreement-between the predictions of the-error analysis and the performance of the fabricated components is observed.