We have observed what we believe to be a new phenomenon in nanocrystalline diamond membranes. The optical thickness of the membrane is changed under laser irradiation, which leads to a spectral shift of interference fringes in the transmission and photoluminescence spectra of high-quality thin self-supporting nanocrystalline membranes. The direction of the spectral shift (red/blue) can be tuned by the ambient air pressure. The effect is reversible and is accompanied by changes in photoluminescence intensity. We interpret the results in terms of the changes in the index of refraction caused by the photoinduced adsorption/desorption of air molecules that subsequently affect the properties of subgap energy states related to the surface and the grain boundaries of the nanocrystals.
© 2010 Optical Society of America
Original Manuscript: September 23, 2009
Revised Manuscript: January 7, 2010
Manuscript Accepted: January 7, 2010
Published: February 11, 2010
Jana Preclíková, Alexander Kromka, Bohuslav Rezek, and Petr Malý, "Laser-induced refractive index changes in nanocrystalline diamond membranes," Opt. Lett. 35, 577-579 (2010)