Fig. 5
From: Free-space transfer of comb-rooted optical frequencies over an 18 km open-air link
Coherent optical communication test over a shortened link of a 1.4 km distance. a Binary phase-modulation is made at a 1 Gbps transmission rate using an electro-optic modulator (EOM). At the receiving site, incoming carrier signals are de-multiplexed through a wavelength division multiplexer (WDM), demodulated using an optical hybrid (OH) device, and finally converted by balanced photo-detectors (BPDs) to the in-phase (I) and quadrature-phase (Q) signals. (Inset) The measured optical power is for λc transmitted with 100 mW power. b Performance evaluations in terms of eye diagrams, constellation diagrams, and error vector magnitudes (EVMs) before and after phase noise compensation
