Low-threshold and quasi-single-mode random laser within a submicrometer-sized ZnO spherical particle film

An unique random laser exhibiting quasi-single-mode and low lasing threshold is developed by a homogenized submicrometer-sized zinc oxide particle film dispersed with intentionally introduced polymer particles as point defects. Such unique random lasing is dominantly initiated at the defect sites, although multi-mode peaks with a collapsed broad emission spectrum are observed at the defect-free sites as in the conventional random lasers. Thus our proposed simple structure can possibly provide the controllability of lasing properties even in random structures.