Fig. 1. Sketch of the Vulcan OPPEL laser system.

Fig. 2. Simulated spectra at each stage of the system with LBO and the front end with BBO.

Fig. 3. Simulated spectra at each stage of the system compared with the expected efficiency of the compressor.

Fig. 4. Measured spectrum of the Ti:sapphire system showing intensity modulation.

Fig. 5. Sketch of the picosecond mJ-level front end experimental setup. The commercial Ti:sapphire oscillator (Venteon) and the two commercial RGAs (S-pulse and Magma25) are seeding and pumping the four NOPA stages, respectively. The compact seed stretcher is made by two BK7 glass blocks, as shown below the Venteon box. The violet dashed boxes are hybrid achromatic telescopes (ACTs, described in Section 5) with a 2× magnification ending with an off-axis parabola (OAP), and the orange dashed boxes between NOPA2 and NOPA3 show achromatic-lens telescopes (three-lens systems) for the propagating broadband signal; meanwhile, the vacuum spatial filters (VSFs) in the light blue dashed boxes show the under-vacuum telescopes (two-lens systems) for the Magma25 RGA. Note: 4-pass MC, 4-pass Martinez compressor; D, Dazzler, spectral shaping and stretching stage; SHG, second-harmonic generation stages.

Fig. 6. Spatial profile of (top) the S-pulse output on the SHG crystal and (bottom) the SHG pump.

Fig. 7. (Top) BBO efficiency (η) and stability considering initial intensity variation in the ±5% range. (Bottom) SHG spectrum (S_2ω) with BBO as a nonlinear crystal.

Fig. 8. Spatial profile of (top) the Magma25 output on the SHG crystal and (bottom) the SHG pump.

Fig. 9. Spectra related to the signal and the NOPA2 stage.

Fig. 10. Near-field spatial profile of the output of (top) the first and (bottom) the second amplification stages.

Fig. 11. Stability measurements performed on the NOPA2 pulses power reveal that the system is autonomously stable for about 22 min with RMS values of 3.7%. The NOPA1 PD signal value is increased by a factor of 0.3V to be better represented in the figure.

Fig. 12. Spectra related to the NOPA4 stage.

Fig. 13. Near-field spatial profile of the output of (top) the third and (bottom) the fourth amplification stages.

Fig. 14. Stability measurements performed on the NOPA4 pulses power reveal that the system is autonomously stable for about 1 h with an RMS value of around 4%. After 1 h, a drift is noticeable and the RMS value is degraded to 10%.

Fig. 15. Single-grating compressor stage sketch. Note: CM, corner mirror; M, mirror; GR, grating (line density = 1000 lines/mm, θ_inc= 41°, θ_out = 0°); L, achromatic lens (f = 15 cm), d_GR–L ~15 cm and d_GR–M2 ~35 cm.

Fig. 16. Profiles of compressed pulses measured with SPIDER diagnostics: (a) compressed NOPA4 temporal profile; (b), (c) stability measurement performed on the temporal length of the compressed NOPA4 output reveals that the system is autonomously stable for almost 60 min.

Fig. 17. Sketch of the nanosecond J-level front end experimental setup. The commercial Nd:YAG laser is pumping the three NOPA stages. The violet dashed boxes are hybrid ACTs (described in Section 5) with an OAP and the orange dashed boxes show under-vacuum achromatic-lens telescopes (three-lens systems) for the propagating broadband signal; the VSF light blue dashed boxes show the under-vacuum telescopes (two-lens systems).

Fig. 18. Design of a Nd:glass chain for the first high-energy pump. A 100 mW CW laser is sliced with a fiber EOM and successively amplified in a fiber to reach the nJ level. This is then amplified in an RGA to 1 mJ and injected into the chain. Note: F1, F2, Faraday; 9AMP, 16AMP, 25AMP, 45AMP, amplifiers with respective diameters in mm; SF, spatial filter; L, lens; PH, pinhole; VSF1, VSF2, vacuum spatial filters; RWP, rotating wave-plate to control output energy; λ/2, half-wave plate.

Fig. 19. Sketch of the upgraded air-cooled disk amplifier.

Fig. 20. Telescope between the ns OPCPA and the first high-energy OPCPA stage: (a) sketch in the OpticStudio environment; (b) residual optical path.

Fig. 21. Architecture of the high-energy nanosecond compressor.

Table 1. Comparison of the three evaluated nonlinear crystals to be implemented in the Vulcan OPPEL system at different central wavelengths.

Table 2. Summary of the simulation parameters regarding the NOPA block stages.

Table 3. Summary of the ҼJ-level NOPA stages.

Table 4. Summary of the mJ-level NOPA stages.

Table 5. Summary of the J-level nanosecond NOPA stages.

Table 6. Summary of the mJ-level NOPA stages.