Ultrafast beam self-switching by using coupled vertical-cavity surface-emitting lasers

Dynamic beam switching of vertical-cavity surface-emitting lasers (VCSELs) has important applications for switching and routeing in optical interconnect networks. VCSEL arrays of various kinds have been quite extensively researched for tailoring and engineering near- and far-field patterns. In this paper, a new method of directional beam switching is proposed that uses two coupled VCSELs. When two VCSELs are coupled by a small separation and biased at the same steady current near threshold, then the resulting light output is dynamic at an extremely high frequency. The model equations are based on an approximation to the semiconductor Maxwell-Bloch equations. The simulations are for coupled VCSELs operating at 980 nm with circular current apertures of 5.6 μm diameter. Figures of the results will show far-field beam intensity patterns during a cycle of oscillation. The simulation results show directional switching at a speed of about 40 GHz and between directions about 8° apart. Results of addition simulations are also presented. Simulations that use two square VCSELs show that the frequency of oscillation increases to 50 GHz and that the far-field pattern remains similar. Finally, for four round VCSELs in a square pattern, two far-field circularly shaped beams moved left and right at a frequency of 50 GHz.