Emission Characteristics of a 1.5- m All-Semiconductor Tapered Master Oscillator Power Amplifier

We present experimental results on the emission characteristics of a 1.5-μm distributed feedback (DFB) tapered master oscillator power amplifier (MOPA) in a wide range of steady-state injection conditions, showing different dynamical behaviors. A detailed analysis of the optical and radio-frequency spectra has allowed the identification of three different emission regimes: i) stable amplified DFB emission, but with wavelength jumps when sweeping the injection currents; ii) multimode Fabry-Perot (FP) operation of the complete MOPA cavity; and iii) self-pulsed operation at frequencies between 5 and 8 GHz. The quasi-periodic occurrence of these emission regimes as a function of the injected currents is interpreted in terms of a thermally tuned competition between the modes of the master oscillator and the compound cavity modes. The physical origin of the wavelength jumps and of the alternation between regimes is discussed.