Aashna Pragati, Thyagarajan K
Opt Lett. 2021 Apr 1;46(7):1486-1489. doi: 10.1364/OL.418085.
A comprehensive study of two simultaneous three wave mixing processes, a second harmonic generation followed by difference frequency generation, under nonlinear stimulated Raman adiabatic passage (STIRAP) is presented. An input pump is up-converted to its second harmonic, which then gets down-converted to a signal and idler pair with frequencies lying very close to the input pump in such a manner that complete conversion from the pump to the signal and idler takes place without exciting the second harmonic under counterintuitive adiabatic passage. This process involves nonlinear STIRAP with a nonlinear dark state similar to atomic population transfers, and we bring an analogy from atomic systems to our nonlinear dynamics to linearize the problem and analytically obtain the adiabaticity condition required for complete conversion. We also show that the nonlinear STIRAP mechanism results in a large bandwidth of about 380 nm with almost complete conversion of the pump to the signal and idler.
本文介绍了在非线性受激拉曼绝热通道（STIRAP）下对两个同时发生的三波混频过程的综合研究，这两个过程是先进行二次谐波产生，然后进行差频产生。输入泵浦光被上转换为其二次谐波，然后该二次谐波再被下转换为一对信号光和闲频光，其频率非常接近输入泵浦光，使得在反直觉绝热通道下能够在不激发二次谐波的情况下实现从泵浦光到信号光和闲频光的完全转换。这个过程涉及到具有类似于原子布居转移的非线性暗态的非线性STIRAP，我们从原子系统引入类比到我们的非线性动力学中，以使问题线性化，并通过解析得到完全转换所需的绝热条件。我们还表明，非线性STIRAP机制导致了约380nm的大带宽，并且泵浦光几乎完全转换为信号光和闲频光。
