THz-induced gas alignment in dispersionless field enhancing waveguides.

We demonstrate a versatile THz waveguide platform for tailored THz-induced orientation and alignment of gas molecules. The underlying waveguide structure is dispersionless, with a refractive index close to one, and enhances the electric as well as the magnetic field up to a factor of five. These properties increase the detected transient birefringence signal by more than an order of magnitude compared to conventional THz free space focusing. We apply this new platform to align two molecular systems and compare the results to theory. Furthermore, we present THz pulse shaping for coherently controlled alignment.