| We study experimentally and numerically the existence of delay interference in two semiconductor lasers coupled unidirectionally via two different paths. The experimental setup consists in two semiconductor lasers coupled unidirectionally. The emitter laser oscillates chaotically due to the action of delayed feedback, sending its signal to the receiver via two different paths with two distinct delays. In order to control the relative influence of the two delay times, we introduce an optical attenuator in one of the paths. Controlling the attenuation, we are able to synchronize the lasers with the lag time of either one path or the other. In order to understand how information is transmitted in the presence of multiple paths connecting two nodes in a network, we modulate the emitter laser with a periodic signal. We analyze the capacity of the receiver laser to filter a modulation introduced in the emitter laser, in the case where both delays dominate equally the dynamics (delay interference). The experiments show that chaos-pass filtering occurs even in the case of symmetrical synchronization, which is necessary for any information to be transmitted down a system with multiple paths. Once experimentally proved that chaos-pass filtering is possible, we analyze the viability of message recovery for different setup configurations. To that end, we studied the effectiveness of the message recovery for different relative influences of the two paths. The results obtained might shed light into how information is transmitted in a network where the nodes are linked via multiple paths. |
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