Switched Wave Packets with Spectrally Truncated Chirped Pulses

A new technique for obtaining switched wave packets using spectrally truncated chirped laser pulses is demonstrated experimentally and numerically by one-dimensional alignment of both linear and asymmetric top molecules. Using a simple long-pass transmission filter, a pulse with a slow turn on and a rapid turn off is produced. The degree of alignment, characterized by $\langle\cos^2\theta_\text{2D}\rangle$ rises along with the pulse intensity and reaches a maximum at the peak of the pulse. After truncation $\langle\cos^2\theta_\text{2D}\rangle$ drops sharply but exhibits pronounced half and full revivals. The experimental alignment dynamics trace agrees very well with a numerically calculated trace based on solution of the time-dependent Schr\"odinger equation. However, the extended periods of field-free alignment of asymmetric tops following pulse truncation reported previously is not reproduced in our work.