Résumé
Single longitudinal mode lasers emitting at 1.5 micrometers are attractive as light sources for low transmission loss (0.15 dB/km) and low dispersion (10 ps/nm/km) optical transmission systems. In distributed feedback (DFB) lasers, the corrugation grating near the active layer selects the emission wavelength. The realization of very good uniformity in composition and thickness on a large wafer allows a uniform Bragg wavelength. In this paper, the static characteristic and stability of DFB lasers emitting at (lambda) equals 1.55 micrometers are presented. It is important to know these data in order to compute the equivalent noise circuit of the DFB laser. The voltage noise of the laser diode Svd (V2/Hz) and the coherence function (gamma) vd-Iph2 between electrical noise and optical noise SIph (A2/Hz) are shown for the first time. Analytic expressions for the electrical noise spectral density Svd(f) and the optical noise spectral density SIph(f) agree with experimental results given by noise measurements.