In photonic label routing networks, optical recognition of optical labels is one of the key functions. We propose a passive waveguide-type device for recognition of optical coded labels. We consider quadrature-phase-shift-keying (QPSK) coded labels. The basic module of the proposed device consists of a 3-dB directional coupler, two Y-junctions, and an asymmetric X-junction. By using interference between an optical pulse of each coded bit and a identifying bit pulse, the basic module distinguishes optical phase of the QPSK signal in a self-routing fashion of the identifying bit pulse. QPSK codes consisting of plural bits can also be recognized by connecting the basic module devices in a tree structure through a phase adjustment circuit. The performance of the proposed basic module is confirmed by simulation using beam propagation method (BPM).
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