Polarization properties of the luminescence from silicon nanocrystals

Polarization dependent photoluminescence (PL), time-resolved PL and PL excitation experiments are performed in order to clarify the origin of the linear polarization of the PL of porous silicon excited by linear polarized light. It is shown that this effect, when PL is excited significantly above the detection energy, is not related to a coherent exciton alignment or selective optical excitation of those nanocrystals whose transition dipole moments are oriented parallel to the polarization vector of the exciting light. The experimental results are interpreted in the framework of a dielectric model assuming aspheric nanocrystals

Polarization properties of the luminescence from silicon nanocrystals

Polarization dependent photoluminescence (PL), time-resolved PL and PL excitation experiments are performed in order to clarify the origin of the linear polarization of the PL of porous silicon excited by linear polarized light. It is shown that this effect, when PL is excited significantly above the detection energy, is not related to a coherent exciton alignment or selective optical excitation of those nanocrystals whose transition dipole moments are oriented parallel to the polarization vector of the exciting light. The experimental results are interpreted in the framework of a dielectric model assuming aspheric nanocrystals

Giant birefringence in multislotted silicon nanophotonic waveguides

Abstract: We demonstrate record giant birefringence, nearly twice as large as has previously been achieved (Δn group = 1.5 over more than 60 nm of bandwidth near λ = 1550 nm) using a multi-slotted silicon nanophotonic waveguide. The birefringence is optimized by the use of materials with high refractive index contrast to create a compact single-mode waveguide, and the etching of deeply sub-wavelength channels within the waveguide, which are strongly coupled in the near field and separated by narrow air channels of optimimum lateral width. When used as a polarization-selective delay element, the delay-bandwidth product per unit length is 46.6/mm over a bandwidth of 8.74 THz. We also design and demonstrate mode shaping of both the TE and TM polarizations to achieve near-identical coupling to a macroscopic external object, such as a lensed fiber or detector