Abstract
We propose and demonstrate a polarization-time coding (PTC) method which can effectively compensate both the CD and first order PMD in direct-detected OFDM transmission. Compared with the previous methods, the proposed PTC not only alleviates the need for the complex dynamic polarization controller but also exhibits superior transparencies to both the OFDM format and transmission data rate. For the proposed PTC method, we have analytically derived the transmission model with CD and first order PMD, and theoretically prove the PTC indeed can jointly compensate both CD and PMD. The numerical results show that, with the PTC method, both the previously proposed gapped and interleaved OFDM formats behave virtually immune to both CD and PMD with a price of 3-dB OSNR penalty in back-to-back (BtB). Aimed to mitigate this BtB 3-dB penalty, further partial PTC approach is proposed for trading the PMD tolerance with the BtB OSNR sensitivity. The interleaved OFDM system is found to gain profits in terms of lower sensitivity with the partial coding.
Highlights
Optical frequency division multiplexing (OFDM) has attracted lots of attentions due to its ability to compensate the linear impairments enabled by powerful electrical signal processing [1,2,3,4,5,6,7,8,9,10]
In order to mitigate these negative side-effects brought by the polarization-time coding (PTC) approach, we further propose the partial PTC approach which is designed for combating the polarization mode dispersion (PMD)
We have proposed the PTC approach that provides the DD-OFDM signal immunities against both CD and PMD
Summary
Optical frequency division multiplexing (OFDM) has attracted lots of attentions due to its ability to compensate the linear impairments enabled by powerful electrical signal processing [1,2,3,4,5,6,7,8,9,10]. Later a self-polarization diversity receiver which collects the data on both polarizations by rotating the carrier’s SOP by 90 degree has been proposed as a full PMD compensator without the need for an adaptive PC [9]. This method uses a colored fiber Bragg grating (FBG) to separate the carrier and data sideband which excludes its application on other spectrally efficient gap-less OFDM formats [6,7]. In [10] we have proposed and demonstrated a PMD-tolerable DD-OFDM transmission using the polarization-time coding (PTC) which makes the receiver colorless, insensitive to input SOP, and transparent to both data format and bandwidth. The simulation results show that the interleaved OFDM can benefit from the partial PTC in terms of the lower OSNR sensitivity with different DGD values; while the partial PTC is found to hardly improve any performance for the gapped OFDM systems
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