Mid-IR to near-IR image conversion by thermally induced optical switching in vanadium dioxide

We demonstrate the image conversion from mid-IR to near-IR (NIR) exploiting high-contrast optical switching in vanadium oxide thin-film layers. The intensity distribution of a mid-IR beam is converted to NIR wavelengths exploiting the strong reflectivity changes induced by optical pumping in the mid-IR. We show an experimental setup in which the radiation of a Tm-doped fiber laser at 1940 mu m and a carbon dioxide at 10.6 mu m has been converted to both 850 nm and 1064 nm. The resolution was 35 mu m and was reached by using an inexpensive CCD camera. The sensitivity of the device increases linearly with sample temperature. We measured a threshold of 144 mW/cm(2), with a sample temperature of 62 degrees C. (C) 2010 Optical Society of America