WDM-POLSK Transmission Systems by Using Semiconductor Optical Amplifiers

The authors demonstrate the potential of using POLarization Shift Keying (POLSK) modulation format combined with semiconductor optical amplifiers (SOAs) in wavelength division multiplexing (WDM) transmission systems. The constant intensity of the POLSK modulation format allows for substantial removal of cross-gain-modulation impairments in SOAs so that practical amplifier spacing values (more than 100 km) are demonstrated in various different experimental configurations. Record WDM transmission experiments at 10 Gb/s by using SOA-based amplification are presented in short and medium reach system architectures using either single mode fiber or nonzero dispersion shifted fiber

I. Introduction

Semiconductor optical amplifiers (SOAs) could be an interesting alternative to common erbium-doped fiber amplifiers (EDFAs), owing to their larger bandwidth, lower size, power consumption, and potential high output power [1], [2]. SOAs could particularly compete against EDFAs for metro and extended-metro systems, which today represent the most interesting market segment. However, SOAs cannot be considered for long-haul applications. In that case, many amplifiers have to be cascaded, and thus the worse noise figure (around 7–9 dB) and the non-negligible polarization dependent gain (PDG) of the SOAs can have a major impact on the system.