Directly modulated quantum-dash mode-locked lasers for millimeter-wave over fiber applications

A directly modulated quantum dash mode-locked laser is proposed for a 50-GHz millimeter-wave over fiber architecture. This advancement offers enhanced fiber-wireless communication capabilities, facilitating coverage of 15-km SMF and 2-m wireless QPSK transmissions. By utilizing the directly modulated laser (DML), we have successfully achieved an optical heterodyne mmW frequency of 50 GHz with exceptional stability. Notably, the measured RF beat-note 3-dB linewidth of the QDash DML is significantly reduced to 2.4 kHz, without the need for any optical feedback scheme. This DML-based hybrid architecture demonstrates the potential to seamlessly integrate with existing optical and wireless networks for next-generation indoor and short-reach mobile communications.