Experimental demonstration of 260-meter security free-space optical data transmission using 16-QAM carrying orbital angular momentum (OAM) beams multiplexing

We experimentally demonstrate a 260-meter security free-space optical data transmission link using orbital angular momentum (OAM) beams multiplexing and 16-ary quadrature amplitude modulation (16-QAM) signals. We study the beam wandering, power fluctuation, channel crosstalk, bit-error rate (BER) performance, and link security.