In photonic label routing networks, recognition of optical labels is one of the key functions. We have proposed passive waveguide-type devices for recognition of optical labels coded in quadri-phase-shift-keying (QPSK) form. In this paper, we consider wavelength dependence of the devices. The basic module of the proposed device consists of a 3-dB directional coupler, two Y-junctions, and an asymmetric X-junction. The Y-junction and an asymmetric X-junction have basically no wavelength dependence. Although the 3-dB directional coupler has weak wavelength dependence, the device for two-symbol label recognition is found to work in wavelength 1.5-1.6 µm. The performance of the device is confirmed by simulation using beam propagation method (BPM).

We previously reported, for a coherent optical code division multiplexing (OCDM) system using fiber Bragg grating (FBG) phase en/decoders, that the signals exhibited phase shift tolerance for a difference between the light source wavelength and the Bragg wavelength of an FBG phase en/decoder when the two signals were multiplexed. However, the phase conditions of only the central wavelength among the ones forming a pulse were analyzed. For a more specific consideration, we calculated the phase of each wavelength forming the decoded pulse. In this report, the measured and calculated reflecting properties were compared and the reliability of the method was confirmed. We calculated the phase conditions of the decoded pulses and clarified the phase characteristics with regard to the phase modulation and the interference between pulses overlapped during decoding. For the realization of an asynchronous access, the FBG phase en/decoders should be designed so that the spreading time is the inverse of 2(texttransmission rate).