- Space-variant polarization manipulation of enhanced nondirectional thermal emission in a narrow spectral peak is presented. The emission is attributed to surface phonon-polariton excitation from space-variant subwavelength Si O 2 Si gratings. Polarization manipulation was obtained by discretely controlling the local orientation of the grating. We experimentally demonstrated thermal emission in an axially symmetric polarization distribution. Theoretical calculations based on rigorous coupled-wave analysis are presented along with experimental results.