Enhancing the Focality of a 10-PW Laser System with a High-Density Deformable Mirror

The role of a large-aperture high-actuator-density deformable mirror (DM) in enhancing the focusing performance of 10 PW laser systems is studied both theoretically and experimentally. Numerical simulations indicate that increasing the actuator density and coupling coefficient of the DM reduces the root mean square (RMS) and gradient root mean square (GRMS) of the corrected residual wavefront, thereby enhancing the energy concentration in the focal spot. However, beyond certain thresholds,further increases in these two structural parameters will lead to diminishing returns in the correction capability of the DM. Experimental validation was carried out using two large-aperture DMs with 121 and 211 actuators, respectively, within the SULF-10 PW laser facility. Results demonstrate that the high-density DM (211 actuators) achieves a residual wavefront error of 0.047 μm RMS and 23.98 nm/cm GRMS, significantly outperforming the lower-actuator-count mirror. After correction, the focal spot with a full width at half maximum (FWHM) of approximately 1.8 μm, with 34% of the energy enclosed within the FWHM was achived—a substantial improvement over the 24% achieved with the 121-actuator DM. Under the 10PW condition, the system can support an output with a focused intensity of ≥10²³ W/cm² after correction by the high-density DM. These findings confirm that optimized large-aperture DMs with high actuator density and coupling coefficient can significantly enhance the focal quality of ultra-high-power laser systems, extending their applicability in strong-field physics experiments.