Silica waveguide technologies for advanced transmission systems

Advanced modulation formats have been attracting considerable attention for application to future optical fiber communication systems because of their high spectral efficiency, high receiver sensitivity and high resilience to linear impairments such as chromatic dispersion and polarization mode dispersion realized with digital coherent detection. For instance, dual polarization, quadrature phase-shift keying (DP-QPSK) modulation is considered to be a promising candidate for commercial 100-Gbit/s transmission systems. In such transmission systems, transmitters and receivers require sophisticated configurations, which will result in higher cost and larger size. Silica waveguide-based planar lightwave circuit (PLC) technology is a promising way to combat this problem because of its excellent optical characteristics, mass producibility and high reliability.