Laser Produces T-Ray Diffractive Elements

To ease the integration of components for terahertz spectroscopy and signal processing, a team at Massachusetts Institute of Technology in Cambridge has fabricated integrated diffractive elements in LiNbO₃ using femtosecond pulses from an amplified Ti:sapphire laser. The group reported the work in the Feb. 3 issue of Applied Physics Letters.

In a demonstration of the technique, the researchers produced grating structures in bulk crystal comprising a series of 0.14-mm-wide grooves separated by 0.2 mm. The laser in the experiment was a homebuilt Ti:sapphire with a repetition rate of 1 kHz and pulse energies of 100 µJ. "Movies" of their studies of phonon-polariton waves traveling through the structures will be available soon at nelson.mit.edu.