Reflective Crosstalk Cancellation in Self-Seeded WDM PON for Mobile Fronthaul/Backhaul

Due to its large capacity and low latency, wavelength-division-multiplexed passive optical network (WDM PON) using self-seeded reflective semiconductor optical amplifier (RSOA) is an attractive, low-cost solution for mobile fronthaul/backhaul. However, multiple reflections in self-seeding cavity lead to reflective crosstalk, degrading its transmission performance. In this paper, reflective crosstalk in self-seeded RSOA under different bias conditions is experimentally characterized by its pulse response, and then novel feedforward and feedback approaches are proposed to suppress the reflective crosstalk in self-seeded WDM PON. Experimental results using a simple delay and differentiation method show significant reduction in the reflective crosstalk for self-seeded RSOA. With the proposed feedforward crosstalk cancellation, 2.5-Gb/s mobile backhaul using self-seeded RSOA achieves 1.7-dB performance improvement after transmission over 20-km single-mode fiber. In addition, low-cost bandwidth-efficient mobile fronthaul for 24 20-MHz LTE signals is demonstrated using a self-seeded RSOA with only 1.5-GHz bandwidth. With adaptive feedback crosstalk cancellation, the error vector magnitude for the received LTE signal after 20-km standard single-mode fiber transmission in the C-band is improved by 20%.