Hu H, Kong D, Palushani E, Galili M, Mulvad H C H, Oxenløwe L K
Opt Express. 2014 Jan 13;22(1):110-8. doi: 10.1364/OE.22.000110.
We have demonstrated the generation of a 320 Gb/s Nyquist-OTDM signal by rectangular filtering on an RZ-OTDM signal with the filter bandwidth (320 GHz) equal to the baud rate (320 Gbaud) and the reception of such a Nyquist-OTDM signal using polarization-insensitive time-domain optical Fourier transformation (TD-OFT) followed by passive filtering. After the time-to-frequency mapping in the TD-OFT, the Nyquist-OTDM signal with its characteristic sinc-shaped time-domain trace is converted into an orthogonal frequency division multiplexing (OFDM) signal with sinc-shaped spectra for each subcarrier. The subcarrier frequency spacing of the converted OFDM signal is designed to be larger than the transform-limited case, here 10 times greater than the symbol rate of each subcarrier. Therefore, only passive filtering is needed to extract the subcarriers of the converted OFDM signal. In addition, a polarization diversity scheme is used in the four-wave mixing (FWM) based TD-OFT, and less than 0.5 dB polarization sensitivity is demonstrated in the OTDM receiver.
我们已经通过在具有等于波特率（320 Gbaud）的滤波器带宽（320 GHz）的RZ-OTDM信号上进行矩形滤波，展示了320 Gb/s奈奎斯特OTDM信号的产生，并使用偏振不敏感的时域光学傅里叶变换（TD-OFT）随后进行无源滤波来接收这种奈奎斯特OTDM信号。在TD-OFT中进行时间到频率映射之后，具有其特征性 sinc 形时域轨迹的奈奎斯特OTDM信号被转换为每个子载波具有 sinc 形频谱的正交频分复用（OFDM）信号。转换后的OFDM信号的子载波频率间隔设计为大于变换限制情况，这里是每个子载波符号率的10倍。因此，仅需要无源滤波来提取转换后的OFDM信号的子载波。此外，在基于四波混频（FWM）的TD-OFT中使用了偏振分集方案，并且在OTDM接收机中展示了小于0.5 dB的偏振灵敏度。
