Two-dimensional distributed feedback lasing with colloidal quantum dots in photonic quasicrystals

Abstract

Lasing properties of the two-dimensional (2D) distributed feedback (DFB) lasers can be engineered by replacing either the gain medium or periodic structures necessary for the feedback mechanism. Quasicrystals are the intermediate class between the periodic and random structures. They have high rotational symmetry and more favorable for the generation of photonic bandgap as compared to periodic structures. In our experiment, we designed a pentagonal prism for the holographic lithography to construct a long-range 10-fold rotational symmetry, which exhibits 2D quasiperiodic structures. A solution-processable colloidal quantum dots (CQDs) was spin-coated on the resultant 2D quasicrystals. An analytical model based on the cavity mode coupling effect was developed to predict the output performance of the 2D DFB CQDs photonic quasicrystals laser. The respective optically pumped 2D photonic quasicrystal samples exhibit multi-wavelength lasing emission in different directions due to long-range rotational symmetry. The five DFB lasing spots are symmetrically distributed in the 2D space, the center of the lasing spots is similar to a star shape. The derived analytical model predictions are in line with the experimental results.