Determination of internal parameters in blue InGaN laser diodes by the measurement of cavity-length dependent characteristics

The characteristics of blue InGaN single-quantum-well laser diodes (LDs) emitting at 445nm are investigated with varying cavity length of the LDs from 650to1450μm. From the measurement of cavity-length dependent slope efficiency, internal efficiency and internal loss of LD structures have been determined to be 0.89 and 10.5cm−1, respectively, indicating good quality of the LD structure. In addition, gain parameters have been extracted from the relation of threshold current density and cavity length. It is found that the internal parameters of blue LDs are comparable to those of violet LDs emitting at 405nm.