Chalcogenide glass is photostable
Chalcogenide glasses are useful for their wide transmission range, which extends through the mid-infrared.
Chalcogenide glasses are useful for their wide transmission range, which extends through the mid-infrared. However, light-induced changes in their optical properties are common—for example, photobleaching in germanium-selenium (Ge-Se) glasses and photodarkening in arsenic-selenium (As-Se) glasses. Now, researchers at the East China University of Science and Technology (Shanghai, China) and Lehigh University (Bethlehem, PA) have comingled the two glasses and honed the Ge/As ratio, producing a chalcogenide glass that is photo-insensitive.
Bulk glass samples with GexAs45-xSe55 compositions were fabricated by the melt-quench method, with x equal to 0, 10, 20, and 33. Thin-film (1.0 µm) coatings of the glasses were deposited on microscope slides and probed with a spectrometer as they were illuminated with diode-laser light at 660 nm (near the glasses’ band gap, where photoeffects are large) and 150 mW/cm2. Over a time span of 20 hours, photochanges were nearly absent for an x of 10, whereas for other values of x, the glasses either photobleached or photodarkened. The researchers are now testing the Ge10As35Se55 composition for photostability over a time span of months, or maybe years. Contact Himanshu Jain at firstname.lastname@example.org.