PELDOR experiments of the type four-pulse DEER experiments combined, either with a continuous optical pumping and direct EPR detection of the stimulated echo (top spectrum), or with a transient optical pumping pulse and a direct detection of the refocused echo (bottom spectrum).B0 is parallel to the c axis of 4H-SiC. In both PELDOR experiments, B0 = 3297 G, T = 300 K, and the probe microwave frequency is fs = 9.308 GHz, such that the low field EPR line of the V2 spins seen in Figure 3 is here resonantly excited at fs. The microwave pump frequency fp is varied in the range [9.15; 9.4] GHz, thus over 250 MHz, in 250 steps of 1 MHz. Inset: pulses sequences applied: pink: optical pumping (first arrow); red: microwave pulse at fs (second arrow) and fp (third arrow); dark: the spin echo used for direct detection, i.e. the one integrated.