Deslocamento de frequência de laser semicondutor sob injeção óptica externa

Abstract

Nowadays, lasers are used in several areas for various applications. There are different types of lasers (free-electron laser, gas laser, semiconductor laser, etc.) which differ by their characteristics such active region, system size, price, among others. Of these different types of lasers, the diode laser stands out, easy size for transport and handling, frequency range between ∼ 0.2 µm and 2 µm to be chosen during production with a narrow spectral width (may be < 0.01 nm), between other advantages. Thus, diode lasers are used in various areas, whether research or application. At in the field of Atomic Physics, lasers are widely used and laser diodes stand out due to the advantages mentioned above, however such diodes have some limitations. We scanned a laser diode in current to have a frequency sweep, but this becomes a problem when you want large sweeps, on the order of tens of GHz. It was observed in the thesis of S. Alves (ALVES, 2016) that the external optical injection in a diode laser causes a frequency shift and in this work we measure this shift under different parameters in order to understand the phenomenon. For this analysis we used an interferometer and different wavelengths in the injected light to analyze the parameters that appear in the equation that describes the frequency shift, a phenomenon not proporcional with time, but given by a exponential law. Using computational treatment with the Python language after calibrating the experiment with saturated absorption, it was possible to analyze both the constant that represents the amplitude of the frequency shift (A) and the time constant τ that indicates how fast the frequency moves. We also measure threshold current changes. when there is optical injection.