Temporal coherence behavior of a semiconductor laser under strong optical feedback

• Published in: Optics communications Vol. 161; no. 1; pp. 123 - 131
• Main Authors: Daza, Marlon Rosendo, Tarun, Alvarado, Fujita, Katsumasa, Saloma, Caesar
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.1999; Elsevier Science
• Subjects: Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lasers; Optical feedback; Optics; Physics; Semiconductor laser; Semiconductor lasers; laser diodes; Temporal coherence; Optical feedback; Temporal coherence; Semiconductor laser; Fourier transformation; Semiconductor lasers; Visible radiation; Theoretical study; Inverse transformation; Experimental study
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/S0030-4018(99)00005-X

We investigate the temporal coherence properties of a semiconductor laser (SL) under strong continuous-wave optical feedback (OF). The temporal coherence length z c of the 830-nm laser is computed from the inverse Fourier transform of the time-averaged emission spectrum at different feedback strengths. The case of a confocal OF configuration is considered in the experiments. For a given feedback intensity R (0≤ R≤0.76), z c exhibits a hump-like dependence with increasing bias current I. The peak location of the hump shifts to lower I values with increasing R, but the functional dependence of z c with I is generally maintained. For a fixed I, z c decreases monotonically with R, indicating that feedback may be utilized to control the coherence of the laser light source. For R>0.76, no fixed z c values are obtained because the spectra are very unstable. The power output of the laser is also analyzed using the Lang–Kobayashi (LK) model and the predictions are compared with experimental data. The results are utilized to establish the optimal conditions for the use of the laser as an optical signal detector.