Observation of a large optical birefringence effect in a (110) oriented porous silicon layer

We account the observation of the largest reported birefringence effect in a semi-artificial material. An in-plane birefringence of more than 0.7 was observed at the blue-green optical spectral range in a porous silicon film fabricated by electrochemical etching of a (110) Si wafer. Birefringent films are of interest in a variety of applications including sensing and polarization control.