Modal Noise Mitigation in 850-nm VCSEL-Based Transmission Systems Over Single-Mode Fiber

Various short-range optical connections, transmitting either high-bit-rate digital signals or radio frequency analog signals, can exploit 850-nm vertical-cavity surface-emitting lasers as optical source together with the standard single-mode fiber (SSMF) as optical channel. This solution presents attractive features in terms of reduced cost and energy consumption. However, bandwidth reduction due to intermodal dispersion and undesired fluctuations of the received signal due to modal noise are present in this case. Such effects are studied theoretically and experimentally, and a cost-effective solution is proposed to reduce their impact. Hence, connections with SSMF length up to 300 m with 3-dB bandwidth of 2500 MHz are demonstrated, while the modal noise is reduced to a standard deviation of less than 2 dB.