Fig. 1. Schematic diagram of the epitaxial structure for the GaN-based blue-violet LDs.

Fig. 2. (Color online) The optical spectrum of stimulated emission for a GaN-based blue-violet LD. The inset shows the far field pattern of laser beam.

Fig. 3. (Color online) Power–current–voltage (P–I–V) curves of a GaN-based blue-violet LD at room temperature.

Fig. 4. (Color online) (a) Current–voltage characteristics obtained for different values of R between 215 and 260 μm, and (b) the measured data of total resistance (R_t, black squares) as a function of ln(R/r) and the fitting line (red), by using the circular transmission line model for p-GaN Ohmic contact in the GaN-based blue-violet laser diode. The specific contact resistance is as low as 1.1 × 10⁻⁶ Ω·cm².

Fig. 5. Optical power of blue-violet LD as a function of the aging time with a fixed injection current at room temperature.