Mansourzadeh Samira, Vogel Tim, Shalaby Mostafa, Wulf Frank, Saraceno Clara J
Opt Express. 2021 Nov 22;29(24):38946-38957. doi: 10.1364/OE.435344.
We demonstrate a 13.3 MHz repetition rate, broadband THz source with milliwatt- average power, obtained by collinear optical rectification of a high-power Yb-doped thin-disk laser in the organic crystal BNA (N-benzyl-2-methyl-4-nitroaniline). Our source reaches a maximum THz average power of 0.95 mW with an optical-to-THz efficiency of 4×10 and a spectral bandwidth spanning up to 6 THz at -50 dB, driven by 2.4 W average power (after an optical chopper with duty cycle of 10%), 85 fs-pulses. This high average power excitation was possible without damaging the crystal by using a diamond-heatsinked crystal with significantly improved thermal properties. To the best of our knowledge, this result represents the highest THz average power reported so far using the commercially available organic crystal BNA, showing the potential of these crystals for high average power, high repetition rate femtosecond excitation. The combination of high power, high dynamic range, high repetition rate and broadband spectrum makes the demonstrated THz source highly attractive to improve various time-domain spectroscopy applications. Furthermore, we present a first exploration of the thermal behavior of BNA in this excitation regime, showing that thermal effects are the main limitation in average power scaling in these crystals.
我们展示了一种重复频率为13.3MHz的宽带太赫兹源，其平均功率为毫瓦级，通过在有机晶体BNA（N-苄基-2-甲基-4-硝基苯胺）中对高功率掺镱薄片激光器进行共线光学整流获得。在2.4W平均功率（经过占空比为10%的光斩波器之后）、85fs脉冲驱动下，我们的太赫兹源实现了0.95mW的最大太赫兹平均功率，光到太赫兹的效率为4×10，在-50dB时光谱带宽高达6THz。通过使用具有显著改善热性能的金刚石散热晶体，在不损坏晶体的情况下实现了这种高平均功率激发。据我们所知，该结果代表了迄今为止使用市售有机晶体BNA所报道的最高太赫兹平均功率，显示了这些晶体在高平均功率、高重复频率飞秒激发方面的潜力。高功率、高动态范围、高重复频率和宽带光谱的结合使得所展示的太赫兹源对改进各种时域光谱应用极具吸引力。此外，我们首次探索了BNA在这种激发状态下的热行为，表明热效应是这些晶体平均功率缩放的主要限制因素。
