Counter-intuitive strength of electric field induced second harmonic (EFISH) signals at the rear side of thin silicon membranes

Abstract

Electric field induced second harmonic (EFISH) generation typically increases with laser intensity. Therefore, EFISH signals generated at the rear S i / S i O 2 interface by a laser beam transmitted through a thin silicon membrane should be much weaker than the signals generated in reflection at the front surface. The counter-intuitive finding that the signal generated at the rear surface is stronger than the front surface signal [Appl. Phys. B 104, 735 (2011)APBOEM0946-217110.1007/s00340-011-4682-1] is now confirmed by detailed experiments applying 10 to 30 µm thin membranes. Using, in addition, the local laser beam intensity [Appl. Phys. B 123, 253 (2017)APBOEM0946-217110.1007/s00340-017-6824-6] leads to the hypothesis that the quasi-static electric field at the rear interface consists of two counteracting components.

Ab initio nonlinear optics in solids: linear electro-optic effect and electric-field induced second-harmonic generation

“…(2) zyx    . (18) Here the 9 columns correspond to components xx, yy, zz, yz, zy, zx, xz, xy, yx, respectively. Therefore, the effective susceptibility tensor contains the component χ which is also the only second-order component different from zero for zincblende symmetry together with the following three independent components induced by the static field…”

“…Recently, it was also reported that ultrafast recombination together with carrier diffusion can be monitored by EFISH generated by space charge accumulation in the material. [4,17,18].…”