1-Tb/s/3.9-km FSO Communications with WDM-PAM4 Technology and MEMS-Based Four-Lens Setup

The implementation of 1-Tb/s/3.9-km free-space optical (FSO) communication with wavelength-division-multiplexing (WDM)-four-level pulse amplitude modulation (PAM4) technology and micro-electromechanical system (MEMS)-based four-lens setup, is practically achieved. WDM-PAM4 technology greatly increases the transmission rate, and MEMS-based four-lens setup substantially extends the distance of FSO communication. By utilizing two cascaded phase modulator-optoelectronic oscillators, a total wavelength of 20 wavelengths is generated, each wavelength carrying a 50-Gb/s PAM4 signal. An FSO communication with an aggregate transmission rate of 1 Tb/s (50 Gb/s/λ × 20 λ) is achieved. At the reception side, the MEMS-based four-lens setup with a control unit (CU) dynamically adjusts the tilt angle to precisely align the laser beam into the fiber ferrule.