Coherent Emission from GaN Surface Relief Gratings with Different Filling Factors

Coherent emission of the surface plasmon phonon polaritons in GaN surface relief gratings with the filling factors of 75 %, 50 %, and 25 % was investigated experimentally and theoretically. Finding an optimal grating filling factor of 25 % allowed us to observe the excitation of higher order modes and to increase the quality factor of polariton emission by up to 5.8 times demonstrating new approaches for polariton-based components in infrared and terahertz spectrum range.