Hall Layton A, Abouraddy Ayman F
Opt Lett. 2021 Nov 1;46(21):5421-5424. doi: 10.1364/OL.438978.
It has long been thought that normal group-velocity dispersion (GVD) cannot be produced in free space via angular dispersion. Indeed, conventional diffractive or dispersive components such as gratings or prisms produce only anomalous GVD. We identify the conditions that must be fulfilled by the angular dispersion introduced into a plane-wave pulse to yield normal GVD. We then utilize a pulsed-beam shaper capable of introducing arbitrary angular-dispersion profiles to symmetrically produce normal and anomalous GVD in free space, which are realized here on the same footing for the first time, to our knowledge.
长期以来，人们一直认为在自由空间中无法通过角色散产生正常的群速度色散（GVD）。实际上，诸如光栅或棱镜等传统的衍射或色散元件只会产生反常GVD。我们确定了引入平面波脉冲中的角色散为产生正常GVD所必须满足的条件。然后，我们利用一种能够引入任意角色散分布的脉冲光束整形器，在自由空间中对称地产生正常和反常GVD，据我们所知，这是首次在相同基础上实现这一点。
