Experimental validation of a 64-QAM LTE radio-over-fiber and free-space optics link at the 2000 nm band

Radio over fiber (RoF) transmission systems have been developing rapidly, especially for applications in 5G networks. In scenarios unsuitable for fiber-optics, radio over free-space optics (RoFSO) presents a suitable solution. Nevertheless, free-space optics (FSO) suffers from atmospheric conditions. The use of the 2000 nm band offers several advantages over the commonly used 1550 nm region. We focus on proof-of-concept evaluation of such a 2000 nm RoFSO transmission system. Measured characteristics are compared with a similar 1550 nm RoFSO system. We demonstrate both systems for QPSK and 64-QAM LTE formats, at 5 GHz and 10 GHz with a 20 MHz bandwidth.