Reduction of the Intensity Noise by Electric Positive and Negative Feedback in Blue-Violet InGaN Semiconductor Lasers

Reduction of the intensity noise in semiconductor lasers is important subject to extend application range of the device. Blue-violet InGaN laser reveals high quantum noise when the laser is operated with low output power. The authors proposed a new scheme of noise reduction both for the optical feedback noise and the quantum noise by applying electric feedback which is positive type at a high frequency and negative type for lower frequency range. Noise reduction effect down to a level lower than the quantum noise was experimentally confirmed even under the optical feedback. key words: InGaN semiconductor laser, optical pick up, quantum noise, optical feedback noise, electric feedback