Department of Physics, Institute of Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland.
Opt Lett. 2010 Jul 15;35(14):2340-2. doi: 10.1364/OL.35.002340.
We present an amplification medium for optical parametric chirped-pulse amplification that allows for ultrabroadband gain in a collinear configuration. Our approach is based on aperiodic quasi-phase-matching (QPM). For the first demonstration of this method in a mid-IR optical parametric chirped-pulse amplifier, we chose a QPM grating design with a linear chirp of its associated spatial frequencies. The resulting 7.4-mm-long, aperiodically poled Mg:LiNbO(3) amplification crystal has a chirp rate of kappa'=-250 cm(-2) and provides gain over the 800 nm bandwidth centered at 3.4 microm. We were able to generate pulses as short as 75 fs and the pulse energy at the output of the optical parametric amplifier before compression was 1.5 microJ. Low thermal load on the amplification medium allows for operation at a high repetition rate, 100 kHz in our case, and high average power limited only by the available pump power.
我们提出了一种用于光参量啁啾脉冲放大的放大介质，该介质在共线配置中允许超宽带增益。我们的方法基于非周期准相位匹配（QPM）。为了在中红外光参量啁啾脉冲放大器中首次演示该方法，我们选择了具有其相关空间频率线性啁啾的 QPM 光栅设计。由此产生的 7.4 毫米长的周期性极化 Mg：LiNbO(3)放大晶体具有 kappa'=-250 cm(-2)的啁啾率，并在以 3.4 微米为中心的 800nm 带宽内提供增益。我们能够产生最短为 75fs 的脉冲，并且在压缩之前，光参量放大器输出端的脉冲能量为 1.5 微焦耳。放大介质的低热负载允许以高重复率运行，在我们的情况下为 100kHz，并且平均功率仅受可用泵浦功率限制。
