A compact device for converting a beam of high frequency microwaves into nanosecond pulses

What is it about?

We have designed and constructed a module that directs an input terahertz (one million million cycles per second) beam into one of two output channels. Each module contains one silicon wafer; a user can choose the output channel by firing a powerful green laser at this wafer. The laser deposits energy onto the wafer, temporarily and rapidly converting it from a transparent window into a reflective mirror, which redirects the beam. A pair of modules can redirect the beam twice, turning an output channel on and then off to create a single pulse. By stacking additional pairs of modules, one can in principle create an arbitrary number of pulses.

Featured Image

Photo by M.M. on Unsplash

Photo by M.M. on Unsplash

Why is it important?

Sequences of high power terahertz pulses are required for the next generation of wireless communication, fusion energy, and advanced magnetic resonance experiments. Previously, creating just two pulses from a long terahertz beam required a huge amount of space. This is because the terahertz optics and lasers used to activate silicon switches were quite large. In our new design, the optics and lasers are much smaller and simpler, and available as stock. Further, the temporal control of each pulse is controlled electronically, and no longer limited by the physical length of delay stages.