Spectrally efficient and low cost time and wavelength division multiplexed passive optical network systems

Abstract

The next-generation passive optical network stage 2 (NG-PON2) intends to support stacking 10 Gb/s wavelengths and maintaining the compatibility with the deployed legacy passive optical network (PON) systems. Essentially, Time and Wavelength Division Multiplexed-PON (TWDM-PON) is the best solution for NGPON2 that aims to support a symmetric 40 Gb/s data rate transmission, a split ratio of 1:64 and a distance up to 60 km. Unfortunately, most of the existing low cost and practical TWDM-PON solutions are still incapable to support remote users and inefficient for spectral bandwidth in higher services. Typically, low cost transceivers are avoided as they suffer from significant frequency chirp that seriously impact its transmission performance at the bit rate above 10 Gb/s. Therefore, the objectives of this thesis are to improve the current TWDM-PON power budget in supporting more access services reaching the remote customers to enhance the bandwidth capacity at lower cost and to reduce the complexity implementation problem. This is achieved by overcoming the significant frequency chirp of the low cost transceivers used such as reflective semiconductor optical amplifier (RSOA) and directly modulated lasers (DMLs), which are suitable for high data rate transmission. The RSOA chirp is mitigated using a single bi-pass delay interferometer (DI) at the optical line terminal (OLT) while the DML chirp is managed by ensuring its resulting current is in phase with the bandwidth enhancement factor, , at both optical network unit (ONU) and OLT. Apart from that, DML equipped with dispersion compensation fiber (DCF) technique for power budget improvement is also proposed. Furthermore, low cost schemes for even higher data rate TWDM-PON up to 56 Gb/s is proposed utilizing highly spectral efficient 16-quadrature amplitude modulation (16-QAM). The results are obtained from physical layer simulation, OptisystemTrademark and MatlabTrademark, where relevant significant parts are verified through theoretical analysis. The simulation results demonstrate a sufficient dispersion compensation with a record of 56.6 dB power bughet for DML-based TWDM-PON transmission system. While results are not absolute due to variations that can occur in practical implementation, analysis demonstrates the feasibility of the proposed methods.