The violet InGaN multiquantum-well-structure (MQW) laser diode (LD) was grown on epitaxially laterally over-grown GaN (ELOG) on sapphire. The lowest threshold current densities between 1.2 and 2.8 kA/cm(2) were obtained when the number of the InGaN well layer was 2. The LDs showed an output power as high as 420 mW/facet under room temperature (RT) continuous-wave (CW) operation. The lifetime of the LDs at a constant output power of 30 mW was 250 h under CW operation at an ambient temperature of 50 degrees C. After obtaining the ELOG, the GaN growth was continued up to a thickness of 200 mu m by a hydride vapor phase epitaxy method. The InGaN MQW LD was grown on a free-standing GaN substrate which was obtained by removing the sapphire substrate. The LDs with cleaved mirror facets showed an output power as high as 160 mW under RT-CW operation. The fundamental transverse mode was observed up to an output power of 80 mW.