Dermatologists explain the science behind wildly popular treatments like red light therapy, which is now available at home—for a steep price. Full-face LED masks like this one can cost up to several ...

Abstract: We demonstrate a thulium-doped fiber ring laser (TDFRL) integrated with an amplifier, which has a watt-level single-frequency output at 2 $\mu\text{m}$ with a 120-nm wavelength tunability.