942 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 24, NO. 11, JUNE 1, 2012 Low Complexity up to 400-Gb/s Transmission in the 1310-nm Wavelength Domain Jaroslaw Piotr Turkiewicz and Huug de Waardt Abstract—In this letter, we demonstrate low complexity dense wavelength-division multiplexing (DWDM) over a ∼40-km stan- dard single-mode fiber transmission system in the 1310-nm wave- length domain with a total transmission capacity up to 400 Gb/s. The demonstrated system is based exclusively on semiconductor components without any form of dispersion compensation. The system showed excellent performance. The presented results prove that the 1310-nm wavelength domain can support low cost and low complexity high-speed transmission with the wide range applications like the future 400G+ Ethernet. Index Terms— Optical fiber communication, semiconductor optical amplifiers, wavelength-division-multiplexing. I. I NTRODUCTION A GROWING number of optical transmission application areas require features such as: small size, limited power consumption, low latency, low cost, line rates >40 Gb/s and distance up to few dozen kilometers. Such applications include the access/mobile back-haul transmission system, the high speed Ethernet and the data/storage center interconnections. Here, we propose the 1310 nm wavelength domain to realize high capacity, low cost and low complexity transmission. The current applications of the 1310 nm wavelength domain are limited to the upstream channel in fiber to the home systems as well as a newly developed 100G Ethernet standard, where 4×25 Gb/s transmission is utilized [1]. Several laboratory transmission experiments in the 1310 nm wavelength domain have been presented, e.g. [2–3] and the 1310 nm wave- length domain components are under constant development, e.g. [4–5]. Clear eye diagrams of eight separately transmitted 50 Gb/s signals after 40 km of standard single mode fiber (SSMF) employing a praseodymium doped fiber amplifier are presented in [6]. In this letter we present semiconductor- based 8×40 Gb/s and 8×54 Gb/s DWDM transmission over 38 km of SSMF in the 1310 nm wavelength domain. Excellent operation of the system is demonstrated. Manuscript received January 27, 2012; revised March 13, 2012; accepted March 13, 2012. Date of current version April 24, 2012. This work was supported in part by the European Union in the Framework of the European Social Fund through the Warsaw University of Technology Development Program, realized by the Center for Advanced Studies. J. P. Turkiewicz is with the Institute of Telecommunications, Warsaw University of Technology, Warsaw 00-665, Poland (e-mail: jturkiew@tele.pw.edu.pl). H. de Waardt is with COBRA Research Institute, Eindhoven Uni- versity of Technology, Eindhoven 5600MB, The Netherlands (e-mail: h.d.waardt@tue.nl). Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LPT.2012.2191278 (a) (b) Fig. 1. (a) Wavelength band as a function of the SSMF distance. (b) FWM related penalty as a function of the channel spacing and input power. II. CAPACITY CONSTRAINS Considering the SSMF fiber, transmission capacity of the 1310 nm wavelength domain will be limited by the residual chromatic dispersion as well as the four-wave mixing effect (FWM). Taking into account the maximum allowable disper- sion values in the 1310 wavelength domain for SSMF [7] and the tolerance to dispersion of the on-off keying modulated signals the available bandwidth was determined as a function of the SSMF length, Fig. 1a. In the analysis, the 1-dB power penalty dispersion tolerance was set to 60 ps/nm and 38 ps/nm for the signals 40 Gb/s and 50 Gb/s, based on the conducted theoretical analysis and simulations. For the 40 km of SSMF the available bandwidth for the 40 Gb/s signals is 32 nm and for the 50 Gb/s signals 20 nm. The channel spacing between DWDM channels is limited by the FWM effect. Fig. 1b shows the simulated FWM related penalty as a function of the channel spacing and the signal input power for the 40 km long SSMF. In all simulations, the evaluated 40 Gb/s channel was placed at the zero-dispersion wavelength and was surrounded by the 20 linearly copolarized 40 Gb/s DWDM channels, each with a unique bit sequence. A uniform adjacent channel spacing was applied. In the simulations, the nonlinear fiber model was utilized and the fiber parameters followed [7]. Below the 200 GHz channel spacing the signal is significantly distorted by FWM, for the channel spacing >250 GHz the distortions are limited, while not significantly limiting the signal input power. To realize 400 Gb/s transmission utilizing the 250 GHz spacing, the 40 Gb/s signals will occupy 13 nm bandwidth and the 50 Gb/s ones will occupy 10 nm bandwidth. The channel spacing can be maximally set to 600 GHz and to 500 GHz for the 40 and 50 Gb/s signals respectively. Therefore both rates can be applied to realize 400 Gb/s transmission. The 32 nm 1041–1135/$31.00 © 2012 IEEE