Performance Analysis of 40-Gb/s Transmission Based on Directly Modulated High-Speed 1530-nm VCSEL

We propose and experimentally demonstrate the use of a novel-design long-wavelength VCSEL with high direct-modulation speed to implement 40-Gb/s transmission suitable for optical interconnects and short-reach scenarios. The single-mode operation, together with the use of a common optical bandpass filter, enables a fiber reach in the kilometer range. The VCSEL is characterized and directly modulated at 40 Gb/s with a power consumption of 18.5 mW. Bit-error-rate (BER) performance has been analyzed for a pseudorandom bit sequence (PRBS) of length 27-1 as commonly done in most of similar studies, as well as for increasing the PRBS lengths up to 231-1 to understand the system limitations when applying more realistic data, so as to induce slower dynamics physical effects such as thermal effects. BER values below common forward error correction threshold are measured without an optical amplification up to 1 km of a single-mode fiber. In particular, error-free operation (BER<10-10) with 1.6 dB of penalty with respect to the back-to-back case was measured for the PRBS length of 27-1.