Yoshihiro Makimoto

Waveguide-Type Optical Circuit for Recognition of Optical QPSK Coded Labels in Photonic Router

In photonic label routing networks, optical recognition of optical labels is one of the key functions. We propose a 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 device in a tree structutre through a phase adjustment circuit. The performance of the proposed basic module is confirmed by simulation using beam propagation method (BPM).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 device 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).

Proposal of Optical Waveguide Circuits for Recognition of Optical QAM Codes

Optical processing of optical labels at high-bit rate is expected in broadband photonic label routers. So far, a variety of optical waveguide circuits and systems to recognize optical BPSK and QPSK coded labels have been studied. In this paper, we propose optical waveguide circuits to recognize optical 16QAM codes. The circuits consist of multi-stage connection of previously proposed circuit for QPSK code recognition. The recognition characteristics for 16QAM codes are theoretically analyzed. To confirm the recognition principle, FD-BPM simulation is performed with a two-dimensional model. Scaled circuits for recognition of 2-symbol 16QAM coded labels and 64QAM codes are also discussed.

Improvement of contrast ratio in quadriphase-shift-keying optical label recognition with passive optical waveguide circuit

Abstract. In photonic label routing networks, recognition of optical labels is one of the key functions. We have proposed waveguide-type optical circuits for recognition of optical labels encoded in quadriphase-shift-keying (QPSK) form. A basic device for the circuits consists of a 3-dB directional coupler, two Y-branches, and an asymmetric X-junction coupler. We employed a scheme of complete interference of optical waves between each coded pulse and a reference pulse in our previously reported paper. The contrast ratio of the output at the destination output port to the outputs at the other ports was reported to decrease to 1.6, 1.28, and 1.13 for two-, three-, and four-stage circuits for recognition of 16, 64, and 256 QPSK labels, respectively. We find optimum circuits with improved contrast ratio of 1.8, 1.6, and 1.47 for 16, 64, and 256 labels, respectively. The recognition operation with the improved circuits is numerically confirmed using the beam propagation method. Noise tolerance of the proposed circuits is also clarified by numerical simulation. The improved circuits are optimum from the viewpoint of efficient use of optical power and noise tolerance.

Wavelength dependence of waveguide-type optical circuit for recognition of optical QPSK labels in photonic router

In photonic label routing networks, optical recognition of routing labels is one of the key functions. We investigate wavelength dependence of a passive waveguide-device for QPSK labels. The function is confirmed by BPM simulation.

Proposal of waveguide-type optical circuit for recognition of optical QPSK coded labels in photonic router

In photonic label routing networks, optical recognition of optical labels is one of the key functions. We propose a passive waveguide- device for recognition of QPSK labels. The function is confirmed with BPM simulation.

Integrated-Optic Circuits for Recognition of Photonic Routing Labels

An optical fiber provides enormous capacity of more than tens terabits per second for transmission in photonic networks, whereas packet processing in network nodes will become a bottleneck for large-capacity networking. For realization of large-capacity and high-speed photonic networks, fast optical processing without conversion to electric signal is preferable (Seo et al., 1996; Blumenthal et al., 2000). Photonic routing has been attracting much interest to overcome the bottleneck of routing function in high-speed networks. In particular, photonic label routing network is expected to provide fast routing of packets at high-bit rate with simple processing. So far, various methods for optical label encoding and decoding have been studied (Kitayama et al., 2000; Goto & Miyazaki, 2005). As one of the nature of light, phase of coherent light has been effectively used in various optical systems, where the interference behavior between multiple signals can be easily used. Using this feature, label recognition techniques have been investigated for photonic routers based upon optical code correlation. However, most of the proposed systems cannot recognize all the binary codes because only the codes that provide enough discrimination between auto-correlation and cross-correlation can be recognized. In addition, in most systems, each optical integrated circuit recognizes only one label (Wada et al., 1999; Takiguchi et al., 2002). Therefore, it is necessary to prepare multiple correlators at each node in order to recognize all the routing labels. On the contrary, for processing of multiple labels, Moriwaki et al. (Moriwaki et al., 2005) and Cincotti (Cincotti, 2004) proposed label recognition systems where self-routing architecture was employed for phase-shift-keying (PSK) labels. On the other hand, Glesk et al. reported a demonstration of optical multiple label recognition for on-off keying (OOK) codes at 250Gbit/s using a selfrouting scheme (Glesk et al., 1997). The self-routing of label data stream for label recognition is one of promising methods in label decoding system. Hiura & Goto proposed a label recognition system for OOK labels (Hiura et al, 2005; Hiura et al, 2007a). Although the proposed system can recognize all the binary-code labels, the system requires many optical switches controlled by optical signals. A similar system was also reported by Kurumida et al. (Kurumida et al., 2006). On the other hand, Hiura et al. also proposed an all-optical passive label recognition system for all the binary codes in binary PSK (BPSK) format (Hiura et al., 2006; Hiura et al., 2007b). The label recognition system consists of a tree-structure connection of passive waveguide components named as

Waveguide-type optical circuit for multi-bit address recognition of optical QPSK labels in photonic router

In photonic label routing networks, optical recognition of optical labels is one of the key functions. We propose a passive waveguide-device for recognition of QPSK labels. The function is confirmed with BPM simulation.