Stimulated emission at blue-green (480 nm) and green (514 nm) wavelengths from nonpolar (m-plane) and semipolar (11(2)over-bar2) InGaN multiple quantum well laser diode structures

Stimulated emission (SE) in the blue-green (480 nm) and green (514 nm) regime has been observed, at room temperature (RT) under optical pumping, from nonpolar m-plane (10 (1) over bar0) and semipolar (11 (2) over bar2) InGaN multi-quantum well (MQW) laser diode (LD) structures, respectively, grown on bulk GaN substrates. The emission intensity exhibited a clear threshold behavior with respect to the pump power. Optical anisotropy was also observed between the two perpendicular in-plane directions [(1) over bar(1) over bar 23] and [10 (1) over bar0] for semipolar LD structures, with significantly lower pump thresholds for emission along [(1) over bar(1) over bar 23]. The SE wavelength, measured just above threshold, was blue-shifted with respect to the spontaneous emission wavelength measured just below threshold. These initial results indicate that semipolar (11 (2) over bar2) GaN is a promising orientation for the realization of blue-green and green LDs. (C) 2008 The Japan Society of Applied Physics.