Abstract
It has been recently reported that reflective semiconductor optical amplifiers (RSOAs) can be used as phase modulators for the cost-effective implementation of the high-speed wavelength-division-multiplexed passive optical networks (WDM PONs). For the detection of the phase-shift-keying (PSK) signal generated by using an RSOA, we should be able to estimate its carrier phase accurately at the digital coherent receiver. However, when the baud rate of this PSK signal is set to be much higher than the RSOA's modulation bandwidth, the conventional M-th power algorithm cannot estimate its carrier phase accurately. To solve this problem, we develop a simple carrier-phase estimation technique for the high-speed (>10 Gb/s) PSK signals generated by using bandwidth-limited RSOAs. This technique estimates the carrier phase of the PSK signal by measuring the angular direction of the opening occurred in the trajectory of the phasor diagram. By using the proposed technique, we demonstrate the upstream transmission of the 25.78-Gb/s quadrature phase-shift-keying (QPSK) signal generated by using an RSOA (3-dB bandwidth: 3.2 GHz) in a 60-km reach coherent WDM PON.
Highlights
There have been numerous efforts to realize a cost-effective wavelength-division-multiplexed passive optical network (WDM PON) by using reflective semiconductor optical amplifiers (RSOAs) as colorless optical transmitters [1, 2]
It has been recently reported that reflective semiconductor optical amplifiers (RSOAs) can be used as phase modulators for the cost-effective implementation of the high-speed wavelength-division-multiplexed passive optical networks (WDM PONs)
For the detection of the phase-shift-keying (PSK) signal generated by using an RSOA, we should be able to estimate its carrier phase accurately at the digital coherent receiver
Summary
There have been numerous efforts to realize a cost-effective wavelength-division-multiplexed passive optical network (WDM PON) by using reflective semiconductor optical amplifiers (RSOAs) as colorless optical transmitters [1, 2]. It has been reported that the per-wavelength operating speed of the RSOA-based WDM PON can be increased to >10 Gb/s by utilizing the post-detection electrical equalization [3], optical offset filtering [4], delay interferometer [5], four-level pulse-amplitude modulation (4-PAM) format [6], and orthogonal frequency-division multiplexing [7, 8] All these techniques have utilized RSOAs as intensity modulators. We can estimate the carrier phase of the QPSK signal by measuring the angular direction of this opening By using this simple CPE technique, we successfully demonstrate the upstream transmission of 25.78-Gb/s QPSK signal generated by directly modulating an RSOA (bandwidth: 3.2 GHz) in a 60-km-reach coherent WDM PON
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
