We succeeded in developing InGaN-based green laser diodes (LDs) with a wavelength of 515 nm under continuous-wave (cw) operation by improving the growth condition of epitaxial layers and structures of LDs. The LD structures were grown on conventional c-plane free-standing GaN substrates by metal organic chemical vapor deposition (MOCVD). The threshold current and threshold voltage at 515 nm were 53 mA and 5.2 V, respectively. The lifetime of 510–513 nm LDs was estimated to be over 5000 h under cw operation with an optical output power of 5 mW at 25 °C.

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The stimulated emissions from semipolar InGaN laser diode (LD) structures grown on (112¯2) GaN substrates are observed at room temperature under photopumped conditions. The measured emission peaks are in the photon energy range from 2.62eV (474nm)to3.05eV (405nm), and the emission intensity has a threshold behavior with respect to the pumping power. A strong in-plane optical anisotropy is observed between the two perpendicular directions, [1¯1¯23] and [11¯00], due to anisotropic matrix elements, which depend on the crystal orientation; the stimulated emission measured along the [1¯1¯23] direction occurs with a lower threshold pumping power at a lower energy compared to that obtained along the [11¯00] direction. The experimental results and the valence band calculations indicate that the transverse-electric mode with an electric vector along the [11¯00] direction is dominant for gain formation in semipolar and nonpolar InGaN LDs. Compared to c-plane InGaN LDs, semipolar InGaN LDs have comparable or less threshold pumping powers.

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