Stimulated whispering gallery modes emission from green to UVA realized by AlInGaN based quantum wells microtube

Self-rolling GaN quantum wells microtubes have been fabricated by a photoresist-assisted electrochemical etching method. Different microtubes with whispering gallery modes emitting from the green to ultraviolet range have been demonstrated. Stimulated whispery gallery mode emission from 370 to 460 nm was achieved with lasing line-width less than 0.087 nm and a threshold as low as 0.12 mJ cm(-2). Such advanced optical properties can be attributed to the larger mode gain obtained by overlapping the active region with the optical confinement layers. The number of modes was greatly suppressed simultaneously leaving only basic radial modes due to the ultra-thin cavity wall.