Teruhiko Kudou

Hierarchical optical path cross-connect systems for large scale WDM networks

Hierarchical optical path architecture consisting of wavelength-division multiplexing (WDM) bands and channels are suitable for large-scale WDM backbone networks. A hierarchical optical path crossconnect system (OPXC) using a matrix WDM scheme is proposed as a reliable and economical high-performance node architecture.

Theoretical basis of polarization mode dispersion equalization up to the second order

We introduce a theoretical basis of polarization mode dispersion (PMD) equalizers based on the operator representation of PMD using Taylors expansion. The two types of configuration of PMD equalizers are derived as the inverse of diagonalization operators and delay time difference compensation. One is a type using physical rotation of quarter wave phase plates. The other is a type using variable phase shifters suitable for PLC integration. Waveform comparison algorithm was simulated to show the existence of multiple equivalent optimum points due to the symmetry and periodicity of optical circuits. The second order PMD equalization is discussed briefly on the case of cascading the first and the second PMD equalizing circuits with two different polarization state converters.

Synthesis of grating lattice circuits

The realization of high-performance components based on optical infinite impulse response (IIR) filter design theory is desirable for next-generation global optical networks. Previously proposed IIR filter synthesis methods are matrix factorization techniques for a lattice circuit using ring resonators. The size of ring resonator limits the bandwidth of the lattice filters. In this paper, two configurations of grating lattice filters are synthesized by using a scattering matrix representation for the grating. The grating is one of the most powerful optical elements both in fiber optics and photonic integrated circuits. One configuration is a serial grating lattice filter configuration and the other is a parallel grating lattice filter configuration. The actual frequency response of the synthesized grating lattice filter is calculated to show the design limitation due to the frequency response of the element gratings.

Nonlinear polarization-mode dispersion

Nonlinear effect of polarization-mode dispersion (PMD) will become important in future transoceanic optical networks and wavelength-division multiplexing (WDM) optical path networks with optical amplifier repeaters. The nonlinear variation of transfer function matrix due to optical Kerr effect is very important because the birefringence of a very long transmission line varies sufficiently as accumulation of self-phase modulation and cross-phase modulation between the orthogonally polarized propagation modes. This situation seems analogous to a nonlinear Fabry-Perot resonator with very large single-path phase-shift. In this report, we measure the nonlinear variation of optical transfer function matrices using an optical network analyzer. The nonlinear variation of the transfer function matrix makes it possible to calculate nonlinear PMD.

AWG-DMUX transmission characteristics improvement using grating lattice filters

Synthesis methods of grating lattice filters (GLFs) with poles and zeros are derived. AWG-DMUX cross talk is improved drastically by using GLF with shaper filter characteristics and small size.