Laser Optimization Guidelines for Dispersion Supported Transmission Systems Operating at Arbitrary Bit Rates

Abstract

Laser guidelines for the performance optimization of dispersion supported transmission (DST) systems operating at arbitrary bit rates, not exceeding 40 Gbit-s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , are presented. These laser guidelines are derived by numerical simulation for 40 Gbit-s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and analytically validated for other bit rates. The laser guidelines are settled in order to accomplish two DST system goals: maximizing the back-to-back sensitivity and the total dispersion tolerance, with fixed laser bias and modulation currents, thus avoiding the usual DST laser current tailoring to the fiber length. The laser optimization guidelines are expressed in terms of the intrinsic laser response parameters as in the following. The -3 dB intensity modulation (IM) bandwidth normalized by bit rate must be about 0.7; the zero of frequency modulation response normalized by bit rate must be about 0.75; the damping ratio of IM response must be about 0.7; the steady-state frequency deviation normalized by bit rate must be about 0.55; and the extinction ratio must be about 5.5. Numerical results show that these rules hold for lasers with parasitics with a cutoff frequency as low as 30% of bit rate, as well as for different current pulse shapes, laser gain, and compression models, and receiver electrical filters.