Experimental study of all-optical FSO fiber FSO communication system based on optical CDMA

In this paper, we design and demonstrate a 10 Gb/s all-optical FSO-fiber-FSO experimental system based on optical code division multiple access (OCDMA). Two-dimensional optical encoder and decoder are realized by WSS and optical fiber delay lines. Under moderate and weak turbulence, bit error rate (BER) of the legitimate user is measured. At the receiving power -1.62 dBm, BER of weak turbulence is $3.235\times 10^{-10}$, while BER of moderate turbulence is $1.561\times 10^{-8}$. At the receiving power -4.58 dBm, BER of weak turbulence is $7.152\times 10^{-9}$, while BER of moderate turbulence is $8.361\times 10^{-7}$. On the other hand, the physical layer security will be improved with the increase of eavesdropping distance.