NPGS  : Circular Grating (1)

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The dark center dot and the surrounding circles were exposed by the beam. The dot has a diameter of ~1 um. The pattern has been etched by RIE to a depth of 0.15 um into GaInAsP. About 10 circles are shown, however, the complete pattern consists of hundreds of circles and the outside diameter is a few hundred microns.  This work was done at the National Research Council in Canada and is described in the paper: Electronic Letters, 26 Sept. 1991, Vol. 27, p. 1819.