Optically pumped lasing at 353 nm using non-polar a-plane AlGaN multiple quantum wells over r-plane sapphire

We report an optically-pumped alternative nitride-based laser with room-temperature emission at 353 nm. The active region comprised of non-polar a-plane Al0.04Ga0.96N/Al0.08Ga0.92N multiple quantum wells whereas the lasing cavity consisted of Al0.15Ga0.85N clad and Al0.10Ga0.85N waveguide layers and naturally cleaved facet mirrors. The layers were grown over r-plane sapphire substrates by metalorganic chemical vapor deposition technique. A room temperature lasing threshold for N-2-laser photoexcitation of 110kW/cm(2) and a modal optical gain of 215cm(-1) was measured at the peak emission wavelength.