Chirp Compensation of Directly Modulated 3s-DBR Laser for WDM-RoF-Based Mobile Fronthaul

In this letter, we propose and demonstrate through simulations, a chirp compensation scheme with a directly modulated three section distributed Bragg reflector (3s-DBR) laser, for use in a WDM-RoF-based mobile fronthaul network to eliminate the signal distortion caused by the interplay between laser chirp and fiber dispersion, including RF power fading and the composite second-order (CSO) distortion. Employing the phase section characteristics of the 3s-DBR laser, the frequency chirp of the device is reduced with reverse modulation current injection into the phase section. The simulation results show that with the chirp compensation scheme, reduced DBR laser chirp can be achieved, and error vector magnitude (EVM) of a 12 channel 211-MHz bandwidth filtered-OFDM (f-OFDM) signal with 64-QAM after transmission over 20-km standard single mode fiber (SSMF), can still satisfy the 3rd generation partnership project's (3GPP) requirement.