(a) PL spectra of dye-doped polymeric split-disks made by DLW. Lasing modes separated by the free spectral range are visible. Applying increasing substrate strain results in a reduction of the gap size Δd = −57.5 nm (blue line), −115 nm (red line), and −172.5 nm (black line) that evokes a blue-shift of the lasing modes (indicated with blue and red arrows). To link the presented lasing modes to Fig. 5, we mark them by corresponding symbols (purple hexagon, orange square, and grey star). (b) PL spectra before applying strain (blue line) and after relaxation of the substrate (red line): Although the lasing intensity fluctuates, it can be seen that the lasing modes are located at the same spectral position demonstrating the full reversibility of our tuning approach.