Abstract
Transmitter and receiver IQ imbalance causes image interference that degrades performance in high capacity and high spectral efficiency optical orthogonal frequency division multiplexing (OFDM) schemes. Digital compensation is an attractive method to relax component specifications. In this paper we report the details of a hybrid compensation method for IQ imbalance compensation, comprising of orthogonal training symbol-based method for transmitter-side compensation and an iterative image reduction-based method for receiver-side imbalance compensation. We demonstrate performance improvement using the hybrid method in presence of frequency dependent imbalance by both simulation and back-to-back direct detection optical OFDM experiment. We report on the tolerable limit of transmitter IQ imbalance under presence of carrier frequency offset.
Highlights
With the bandwidth consuming internet-based services becoming widely deployed, backbone network speeds in access of 100 Gbps are expected to be needed in the near future
An arbitrary waveform generator sends out real and imaginary components of a baseband Orthogonal frequency division multiplexing (OFDM) signal, which are upconverted to achieve a band pass OFDM signal by an electrical IQ mixer and the resulting OFDM signal is applied to a Mach-Zehnder modulator (MZM)
The LSB of the optical signal is filtered by optical band pass filter (a 50 GHz interleaver was used) and only the carrier and USB are transmitted down transmission fiber
Summary
With the bandwidth consuming internet-based services becoming widely deployed, backbone network speeds in access of 100 Gbps are expected to be needed in the near future. “Effect of hybrid IQ imbalance compensation in 27.3-Gbit/s direct-detection OFDM transmission,” in Proceedings of Optical Fiber Commun.
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