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Next-generation optical disc systems are attracting strong interest and further increases in their recording capacity and speed are required" 2 . In order to achieve these increases, a high-power blue-violet laser diode is indispensable. On the other hand, the noise characteristic is also an important factor in blue-violet laser diodes for practical use because a high-level of noise raises the jitter level of the optical disc system. In this study, we have successfully fabricated blue-violet laser diodes with high power (100 mW) and low-noise (-130 dB/Hz @5 mW) characteristics.The laser structure was grown on an n-type gallium nitride (GaN) substrate by metalorganic vapor phase epitaxy. It had an active layer sandwiched by aluminum gallium nitride (AlGaN) cladding layers.The active layer had a multiple-quantum-well structure with indium gallium nitride (InGaN) layers as quantum wells. The laser diode fabricated in this study had a ridge waveguide structure with a dielectric current blocking layer. The cavity length was 600 Aim and the reflectivity of the front and rear facets was 5% and 95%, respectively. Figure 1 shows L-I curves under pulsed operation at various temperatures. The pulse width and duty factor are 100 ns and 50%, respectively. There are no kinks up to 120 mW under pulsed operation in a wide temperature range of 10-70°C in this figure. The characteristic temperature (To) is estimated from these curves to be 185 K. The threshold current and slope efficiency at 25°C are 38 mA and 1.4 mW/mA, 150 respectively. The lasing wavelength is 405.3 nm at 25°C under 50-mW CW B Tc=10,25,40,50,60,70°C operation. We consider that these good E Pulse Width=100 ns characteristics are the result of improving 3 100 Duty=50% the crystal quality of the grown materials X L600 /m (L Rf--5% on the GaN substrate. Figure 2 shows the = Rr=95% typical noise characteristics of the device with a light output power of 5 mW. A 0 / high-frequency modulation of 350 MHz / was added in this measurement. The '/ measurement frequency and external 0 cavity length were 16.5 MHz and 45 mm, 0 50 100 150 respectively. The relative intensity noise (RIN) level is lower than -130 dB/Hz for Current (mA) the entire optical feedback range (0.001-10 %) in this figure. Figure 3Fig. 1. L-1 curves measured at temperatures of 10, 25, 40, 50, 60 and 70°C under shows far field patterns (FFP) in the pulsed operation. directions parallel and perpendicular to the