這些結果證實了結合交叉偏振波 (XPW) 與雙重啁啾脈衝放大 (Double CPA) 的前端系統能有效的抑制預脈衝的產生，同時支援更寬的頻寬以產生更短的脈衝。此次NCU 100-TW 雷射系統的升級，為未來需要高時間對比度的高強度雷射電漿交互作用實驗，建立了一個更優良的平台。;Ultrafast， high-intensity lasers are critical tools for frontier study research based on laser-matter interaction， such as Target-Normal Sheath Acceleration (TNSA) and Radiation Pressure Acceleration (RPA). These applications require high temporal contrast quality to prevent the pre-ionization of solid targets before the arrival of the main pulse. The original 100-TW laser system at the National Central University (NCU) exhibited a temporal contrast of approximately 3.2 × 10−8， which required improvement to support highly sensitive high-field experiments. To overcome this limitation and simultaneously shorten the pulse duration， this thesis presents the design， implementation， and characterization of a Double Chirped-Pulse Amplification (CPA) front-end integrated with Cross-Polarized Wave (XPW) generation.
In the front-end， a ring regenerative amplifier was constructed with an intra-cavity spectral shaping filter to counteract gain narrowing， significantly broadening the seed spectrum. The pulse is then directed into an XPW nonlinear temporal filter utilizing BaF2 crystals， which suppresses pre-pulses and further broadens the spectrum. Furthermore， precise dispersion control is essential for achieving transform-limited pulses. Therefore， a dual-input Convolutional Neural Network (CNN) model is proposed to retrieve high-order dispersion coefficients directly from Single-Shot Autocorrelation (SSA) traces， bypassing the limitations of traditional phase retrieval algorithms.
Experimental characterization reveals significant enhancements in the performance of the NCU 100-TW laser system. The use of spectral shaping filter successfully broadened the bandwidth of the regenerative amplifier from 28.5 nm to 51.7 nm. With the XPW process， the output spectral bandwidth further expanded to 67.3 nm and the temporal contrast was enhanced by over three orders of magnitude. Following the upgrade， the compressed pulse duration was reduced to 37 fs with a 40 nm spectral bandwidth， and the temporal contrast effectively enhanced by two orders of magnitude and reached 2.7×10−10 in the -350 ps to -250 ps range.
These results confirm that the Double CPA front-end effectively enhances the temporal profile while supporting broader bandwidths for shorter pulse generation. This upgrade for the NCU 100-TW laser system establishes a better platform for future high-intensity laser-plasma interaction experiments requiring extreme pulse quality.
