Single-mode quantum-dash laser submitted to optical injection: Nonstandard behaviour with respect to the slave pump

Abstract

Almost fifty years after the first experiment by Stover [1], optical injection has been the subject of intense analysis in the last decade, especially for single-frequency laser [2,3]. This paper focuses on the properties of a single-mode quantum dash laser emitting at 1.55 µm, submitted to optical injection. Recent results concern mainly multi-frequency quantum dot or dash lasers emitting at 1.55 µm [4] or single-mode quantum-dot laser emitting at 1.3 µm [5,6]. However, our devices, DFB quantum-dash laser emitting at 1.55 µm [7], doesn't reveal the same behaviour as the one described in [5]. The general properties of this DFB quantum-dash laser are close to the ones of quantum-well lasers [3]. Nevertheless the strong damping factor associated to the quantum-dash lasers modifies totally the response with respect to the pumping parameter of the slave laser. In a conventional laser (bulk or quantum wells), close to threshold, the laser behaves like an optical amplifier, while at a larger pump current, more regimes appear as illustrated in the figure 1, which compares the different regimes in the chart “detuning”- “injected power”. On the contrary, for quantum-dash laser, the tendency is opposite as shown in figure 2. We propose in this communication to detail these trends experimentally and theoretically.