Left: Schematic diagrams of the 10.2-µm seeder system and the proposed 5-pass CO2 amplifier. Right: Streak-camera image of the 10.2-µm pulse.
Energetic picosecond 10.2-μm pulses generated in a BGGSe crystal for nonlinear seeding of terawatt-class CO2 amplifiers
Optics Express 32, 11182–11192 (2024) (Editor’s Pick)
Ya-Po Yang, Jheng-Yu Lee, and Jyhpyng Wang
Energetic picosecond 10.2-μm pulses generated in a BGGSe crystal for nonlinear seeding of terawatt-class CO2 amplifiers
我們展示了一種產生高能量皮秒 10.2 微米脈衝的新方法，此方法基於次奈秒單頻 1338 奈米脈衝和寬頻 1540 奈米啾頻脈衝在 BGGSe 晶體中進行非線性混頻。經過光柵壓縮器壓縮後的 10.2 微米脈衝可用於注入高功率 CO2 放大器。該脈衝的能量可超過 60 微焦耳且擾動為 3.4% (方均根誤差)。由條紋相機配合克爾偏振旋轉進行單擊發脈衝寬度量測，並結合脈衝頻譜的量測，顯示該脈衝寬度在 2.7-3 皮秒之間。數值計算表明，在高氣壓 CO2 放大器中注入此高能量的種子脈衝可引起功率增寬和動態增益飽和產生的拉比翻動。藉此由 CO2 分子的梳狀光譜所導致的脈衝分裂現象可被這些非線性效應極大地抑制。經過多通 CO2 放大器之後，我們預計峰值功率可超過 1 兆瓦。
We demonstrate a new approach to energetic picosecond 10.2-µm pulse generation. The approach is based on nonlinear mixing of subnanosecond single-frequency 1338-nm pulses and broadband 1540-nm chirped pulses in a BGGSe crystal followed by a grating compressor for seeding high-power CO2 amplifiers. Pulse energy exceeding 60 µJ with 3.4%-rms fluctuation can be routinely obtained. Single-shot pulse duration measurement, performed by Kerr polarization rotation time-resolved by a streak camera, along with the pulse spectrum, indicates the pulse duration is between 2.7-3 ps. Numerical calculations show that power broadening and dynamic gain saturation with Rabi-flopping can be induced with such an intense seed in a multi-bar CO2 amplifier. These nonlinear effects greatly suppress pulse splitting due to the comb-like spectrum of the CO2 molecule. A peak power exceeding 1 TW is expected after multipass amplification.