Engineers have developed a new technique to control the polarization state of a laser that could lead to a new class of powerful, high-quality lasers for use in medical imaging, chemical sensing and detection, or fundamental science research.
The researchers developed a specialized artificial material, a type of metasurface, that can tune the laser’s polarization state purely electronically, without any moving parts. The breakthrough advance was applied to a class of lasers in the terahertz range of frequencies on the electromagnetic spectrum, which lies between microwaves and infrared waves.
In their approach, the polarization control is built right into the laser itself, which allows a more compact and integrated setup, as well as the possibility for very fast electronic switching of the polarization. Also, the laser efficiently generates the light into the desired polarization state — no laser power is wasted generating light in the wrong polarization.
The new metasurface covers an area of 2 square millimeters and has a distinct zigzag pattern of wire antennas running across its surface. An electric current runs through the wires, selectively energizing particular segments of the laser material, which allows a user to change and customize the polarization state as needed.