Tuning the Luminescence Response of an Air-Hole Photonic Crystal Slab Using Etching Depth Variation

Detailed studies of the luminescent properties of the Si-based 2D photonic crystal (PhC) slabs with air holes of various depths are reported. Ge self-assembled quantum dots served as an internal light source. It was obtained that changing the air hole depth is a powerful tool which allows tuning of the optical properties of the PhC. It was shown that increasing the depth of the holes in the PhC has complex influences on its overall photoluminescence (PL) response due to the simultaneous influences of counteracting factors. As a result, the maximal increase in the PL signal of more than two orders of magnitude was obtained for some intermediate, but not full, depth of the PhC's air holes. It was demonstrated that it is possible to engineer the PhC band structure in such a way as to construct specific states, namely bound states in continuum (BIC), with specially designed dispersion curves being relatively flat. In this case, such states manifest themselves as sharp peaks in the PL spectra, and have high Q-factors which are larger than those of radiative modes and other BIC modes without such a flat dispersion characteristic.

Automated summary

Detailed studies were conducted on the luminescent properties of Si-based 2D photonic crystal (PhC) slabs with air holes of various depths. Ge self-assembled quantum dots were used as the internal light source. It was found that changing the air hole depth can significantly influence the optical properties of the PhC, with a maximal increase in the photoluminescence (PL) signal obtained for intermediate depths of the air holes. Furthermore, specific bound states in continuum (BIC) with flat dispersion curves were engineered, resulting in sharp peaks in the PL spectra and higher Q-factors compared to other BIC modes without such flat dispersion characteristics.