Pulse Collision Computing with Spiking Micropillar Lattices

Spiking microlasers with integrated saturable absorber have been shown to behave as ultrafast photonic neurons, mimicking many of the main computational properties of biological neurons but with much faster timescales [1] (sub-nanosecond typically). Micropillar lattices can be designed by evanescently coupling the microlasers and have been shown theoretically to sustain saltatory propagation of solitonic-like excitations [2]. They hold good promise for fabrication of advanced and integrated photonic processing circuits. By studying a model for evanescently coupled excitable microlaser lattices with integrated saturable absorber, we have investigated how pulse interaction can lead to non trivial responses [3]. By carefully choosing the system parameters, we show the some-what counter-intuitive result that two counter-propagating pulses from two input ports in a three-port system can collide and exit or not in a third port, thus giving rise to the not-linearly separable XOR response function and to universal logic temporal gates (see Fig. 1). Other types of temporal gates can be obtained such as the temporal OR, AND and NAND gates. We discuss the physics underlying these responses. We also present first experimental results obtained in this system with lattices in the linear geometry, enabling to demonstrate the propagation of spikes, and discuss the extension to the theoretically demonstrated temporal gates.