Anisotropic wet etching on birefringent calcite crystal

In this paper, a mechanism for wet etching on birefringent calcite crystal is discussed. By altering the etchant type, its concentration and the stirring speed, the etching mechanism can be confined within the surface reaction regime, resulting in anisotropic etching. Acetic acid can be used to form V shapes defined by the {101̄1} planes with an intersecting angle of 51 degree. V-groove and blazed grating, with a grating period as small as 2 μm, were successfully fabricated. Such gratings can be used as transmission and reflection devices in the visible and infrared ranges. In addition, a transmission polarization dependent device can also be made by covering the calcite with index matching material.