High speed next generation passive optical networks: performance, cost, and power dissipation

Abstract

The exponential growth of Internet data traffic pushes hard the telecommunication infrastructure for upgrading the transmission data rate. At the optical access level, a passive optical network (PON) is the most popular and lowest cost architecture which enables high speed access for enter prise and private users as well as various backhauling and fronthauling functionalities. Standardized PONs have undergone a number of upgrades in data rates. In order to guarantee a stable return of investment for operators, the co-existence of different generations of PONs on the same fiber infrastructure is ensured via a wavelength division multiplexing (WDM) approach. This leads to a spectrum shortage for future allocations if full co-existence is required. Today's fastest 40 Gb/s TWDM PONs [1] support 10 Gb/s lane rate non-return-to-zero (NRZ). Looking forward, the bandwidth demands continue to rise, thus increasing the per-wavelength bit rate is necessary for a future upgrade beyond 40 Gb/s. For such high data rates, the conventional NRZ format becomes demanding with respect to the required transceiver bandwidth and the acceptable fiber dispersion. As an alternative, advanced modulation formats and efficient signal processing can address the upgrade issue. Recently, research efforts have been focusing on 25 Gb/s or 40 Gb/s per wavelength next generation PONs using either NRZ with chirp management [2], or electrical/optical Duobinary [3–7], PAM-4 [3, 6–8], as well as more complex ODFM [9]. Considering PONs are cost-sensitive applications, intensity modulation and direct detection is highly desirable. Compared to DSP intensive OFDM, electrical/optical Duobinary and PAM-4 with low complex DSPs are potentially costeffective solutions. This paper aims to review and compare a number of implementation options for 40 Gb/s per wavelength high speed PONs using electrical/optical Duobinary and PAM-4. Optical link power budget performance, transceiver cost and power dissipation will be analyzed based on numerical approaches. Experimental demonstrations will also be presented.