Continuous-wave operation of InGaN green laser diodes (LDs) on semipolar f2021g GaN substrates with output powers of over 100 mW in the spectral region beyond 530 nm is demonstrated. Wall plug efficiencies (WPEs) as high as 7.0-8.9% are realized in the wavelength range of 525-532 nm, which exceed those reported for c-plane LDs. The longest lasing wavelength has reached 536.6 nm under cw operation. These results suggest that the InGaN green LDs on the f20 21g plane are better suited as light sources for applications requiring wavelengths over 525 nm.

True green GaInN laser diodes with a lasing wavelength above 525 nm under continuous wave operation have been successfully fabricated on semipolar {2021} GaN substrates by improving both the diode structure and epitaxial growth conditions. At a case temperature of 55 °C, their lifetime was estimated to be over 5000 h for an optical output power of 50 mW and over 2000 h at 70 mW.

We report the growth of BeZnCdSe quantum-well laser diode (LD) structures with a short-period superlattice cladding layer and demonstrate continuous-wave lasing in the pure-green spectral region (545 nm) at room temperature. The threshold current density and voltage of a 5-µm-wide gain-guided laser were found to be 1.7 kA/cm2 and 10.4 V, respectively. This threshold current density is sufficiently low compared with that of InGaN/GaN green LDs.

Double heterostructures ͑DHs͒ consisting of BeZnSeTe active and MgSe/BeZnTe superlattice cladding layers were fabricated on InP substrates by molecular beam epitaxy. By photoexciting the DHs, green lasing emissions at 548 nm were obtained at room temperature. The threshold excitation power density was 70 kW/ cm 2 , from which we estimated the threshold carrier density and threshold current density assuming a green laser diode ͑LD͒ with a BeZnSeTe active layer to be ͑1.4-4.6͒ ϫ 10 18 cm −3 and 0.22-0.73 kA/ cm 2 , respectively. The experiment proved the applicability of BeZnSeTe as an active layer of green LDs.

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