C.R.S. Fludger

Coherent Equalization and POLMUX-RZ-DQPSK for Robust 100-GE Transmission

We discuss the use of a coherent digital receiver for the compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard. We present experimental results on the transmission performance of 111 Gbit/s POLMUX-RZ-DQPSK. For a dense WDM setup with channels carrying 111 Gbit/s with a 50 GHz channel spacing (2.0 bits/s/Hz), we show the feasibility of 2375 km transmission. This is enabled through coherent detection which results in excellent noise performance, and subsequent electronic equalization which provides the high tolerance to polarization mode dispersion and chromatic dispersion (CD). Furthermore, we discuss the impact of sampling and digital signal processing with either 1 or 2 samples/bit. We show that when combined with low-pass electrical filtering, 1 sample/bit signal processing is sufficient to obtain a large tolerance towards CD. The proposed modulation and detection techniques enable 111 Gbit/s transmission that is directly compatible with the existing 10 Gbit/s infrastructure.

Channel Parameter Estimation for Polarization Diverse Coherent Receivers

A robust in-service estimation of fiber channel parameters from equalizer parameters of a polarization diverse coherent receiver is presented. The equations used for estimation are evolved from a theoretical fiber channel model. The theory is validated based on simulations and data from transmission experiments.

Coherent Equalization versus Direct Detection for 111-Gb/s Ethernet Transport

We discuss coherent equalization to realize robust 111-Gb/s transmission. For 111-Gb/s POLMUX-RZ-DQPSK we experimentally show the advantage of coherent equalization over direction detection for compensation of both chromatic dispersion and differential group delay.

Joint-polarization carrier phase estimation for XPM-limited coherent polarization-multiplexed QPSK transmission with OOK-neighbors

We demonstrate joint polarization carrier phase estimation for XPM-limited channels with significant improvements over standard methods, demonstrated on measurements of 43 Gb/s NRZ-CP-QPSK with 10.7 Gb/s OOK neighbors.