Noriaki Kaneda

Frequency Estimation in Intradyne Reception

We report on an optical intradyne receiver experiment with frequency estimation. Frequency estimation allows, if performed prior to block phase estimation or other phase recovery techniques, for a much higher frequency difference between transmit laser and local oscillator laser. We demonstrate the feasibility of our approach in a 20-Gb/s quadrature phase-shift keying experiment

Coherent Receivers for Practical Optical Communication Systems

Coherent receivers that utilize electrical signal processing techniques have attracted increased attention over the last couple of years. In this paper, we will discuss some practical aspects of these receivers and present some recent results.

Digital coherent quadrature phase-shift-keying (QPSK)

Conventional coherent detection attempts to synchronize local lasers with transmit lasers indiscriminately without considering individual noise contributors. Handling each contributor properly, we proposed a novel approach for quadrature-phase-shift-keying to enable realization of coherent communication without need of synchronization

Enhanced FEC OSNR gains in dispersion-uncompensated 10.7-Gb/s duobinary transmission over 200-km SSMF

We report the experimental comparison of 10.7-Gb/s duobinary transmissions using generic Reed-Solomon forward error correction (FEC) and an enhanced FEC. The coding gains of the two FECs after transmission over a dispersion-uncompensated 200-km standard single-mode fiber (SSMF) link are found to be much larger than those quoted in ideal case, with the enhanced FEC further outperforming the generic FEC by /spl sim/3.5 dB. Numerical simulations show reasonable agreement with the experimental results.

Improved polarization-mode-dispersion tolerance in duobinary transmission

Polarization-mode-dispersion tolerance of a low-pass filter duobinary modulation format is investigated. With the optimum residual dispersion, the optical signal-to-noise ratio penalty at a differential group delay of 40 ps is measured to be 1 dB (at BER=6/spl times/10/sup -5/): 1.5 dB less than that without residual dispersion in a 10.7-Gb/s duobinary transmission. Numerical simulations show reasonable agreement with the experimental results.

Modeling accuracy of a fiber-optics test bed using MGF method

The absolute accuracy of modeling a high bit rate optical transmitter-receiver test-bed by using moment generating functions is investigated with extensive system measurements and component characterizations. We achieved a 0.5-dB average optical signal-to-noise ratio accuracy for a 10-Gb/s return-to-zero fiber-optics test bed. The methodology shown here can be very useful for both efficient and accurate component or system engineering.

High-Speed Coherent Optical Receivers Realized in DSP

Digital coherent optical detection has emerged as a promising technology for next generation optical communication. DSP realized in FPGA for coherent optical QPSK receivers has proven its capability in the high-speed optical communication environment.