Detector-Free Bidirectional Symmetric Communication Scheme Based on Compound States of two Mutually Coupled Diode Lasers

Abstract

In recent years a dramatic expansion of internet data traffic has been reported[1]. To provide high data rates in two directions via optical fibers, several methods have been developed. Most of them require both at each end a light source to generate the data and a detector to receive the data[2]. Coupled semiconductor lasers — a system of two spatially separated nonlinear oscillators — are receiving major interest, because of a variety of interesting dynamical phenomena including chaos synchronization[3] and injection locking[4]. In order to realize a communication scheme, where the transmitter unites with the receiver, we take advantage of such a coupled injection locked semiconductor laser setup utilizing two 1550 nm discrete mode diode lasers (DL). In this remarkably simple scheme without any expensive and sophisticated detectors, the data is transmitted exploiting compound states of the coupled laser system containing upstream information of DL1 and downstream information of DL2 simultaneously utilizing the laser as detector principle. The data acquisition is accomplished by evaluating the compound state utilizing the DC-voltage change of both lasers with respect to their solitary, i.e. uncoupled voltage.