Patent ID: 8116343

Claim:
A method of driving a laser diode, wherein, (a) the laser diode includes a laminate structure body including a first compound semiconductor layer, an active layer having a quantum well structure and a second compound semiconductor layer, a first electrode electrically connected to the first compound semiconductor layer, and a second electrode electrically connected to the second compound semiconductor layer, (b) the laminate structure body is made of an AlGaInN-based compound semiconductor, c) the second compound semiconductor layer is doped with 1×10 19 cm −3 or over of Mg, and (d) the absorption coefficient of the second compound semiconductor layer for light with a wavelength of 405 nm is at least 50 cm −1 ; the method comprising the step of driving the laser using a pulse voltage that is 2 or more times higher than a threshold voltage value of the laser.