Mid-IR laser beam quality measurement through vanadium dioxide optical switching.

We present a beam characterization system for infrared lasers which can measure both wavefront and beam profile with visible detectors. While previous studies demonstrated the conversion from the visible to the near infrared, this device exploits the wavelength conversion from the infrared to the visible, which is based on the refractive index change because of the optical switching of a vanadium dioxide layer. This technique can be applied over a broad spectral range from the visible to the infrared and potentially to the terahertz.