Abstract

We propose a downstream/upstream (DS/US) WDM-SDM-PON architecture employing the multicore fiber (MCF) realizing 300Gb/s aggregation DS rate and 20Gb/s US rate per wavelength. Figure 1 depicts the experimental setup. For DS transmission, ten wavelengths with 25GHz channel spacing are selected by a waveshaper from an optical frequency comb generator (OFCG)which is driven by a ECL seed laser centered at 1550.116nm. Then the ten CWs are simutaneously intensity modulated with 5Gb/s baseband QPSK-OFDM signal generated off-line by Matlab, where the IFFT/FFT size is 128 and 63 effective subcarriers are used to convey data information. The length of cyclic prefix (CP) of OFDM signal is 13, which is long enough to conquer the impact of chromatic dispersion of MCF. Boosted by EDFA, the signals are power splitted and simutaneously injected into one of six outer cores of the MCF through the fan-in device. After 60km MCF transmission, the signals are output through fan-out device. The fan-in/fan-out device is fabricated using chemical etched optical fiber bundles method [1]. After pre-amplifier and optical bandpass filter, one wavelength of output signal is directly detected by a photodetector (PD) with 4GHz bandwidth and then sampled by a 20GS/s digital sampled oscilloscope (DSO). Demodulation and bit error ratio (BER) counting are implemented offline. The DS transmission results are illustrated in Figure 2(a). No significant transmission performance deterioration is observed between OB2B and MCF transmission for all six spatial channels, and the BER can be kept under 3.8x10^-3 at the received optical power of -16dBm. For US transmission, a CW laser from ECL is modulated by an IQ modulator with 20Gb/s QPSK signal generated by BER tester (BERT). The signal reusing the same wavelength is transmitted in the inner core of MCF to avoid the interference of Rayleigh backscattering effect. After amplification and filtering, the signal with power of about -1dBm is coherently detected at the optical line terminal. The US transmission result is shown in figure 2(b), which shows that more than 18 dB power budget can be guaranteed.

© 2015 IEEE