Low-crosstalk, filter-free, and secure WDM for optical inter-CubeSat communication using fluorescent fiber antennas

In this paper, a low-crosstalk, filter-free, and secure wavelength-division multiplexing (WDM) scheme based on fluorescent fiber antennas is proposed and demonstrated for optical inter-CubeSat communication (OICSC) systems. The integration of fluorescent fiber antennas in OICSC systems facilitates efficient WDM transmission to enhance the achievable data rate, owing to their inherent optical filtering capabilities. By selecting light-emitting diodes (LEDs) with distinctive emission wavelengths and fluorescent fiber antennas with the corresponding absorption wavelengths, physical WDM signal separation can be achieved to effectively minimize crosstalk at the receiver side. Furthermore, in order to address the performance imbalance across different wavelength channels and enhance transmission security, a chaotic two-dimensional pairwise coding (2D-PWC) scheme is further proposed for the WDM-OICSC system using fluorescent fiber antennas. Proof-of-concept experiments are conducted to verify the feasibility of using fluorescent fiber antennas to achieve low-crosstalk, filter-free, and secure WDM transmission in OICSC systems. Experimental results indicate that the proposed WDM-OICSC system using fluorescent fiber antennas exhibits a negligible crosstalk between two wavelength channels and the application of chaotic 2D-PWC can achieve enhanced bit error rate (BER) performance while ensuring transmission security. Specifically, a usable bandwidth of 18 MHz is obtained at the BER threshold of 3.8 × 10^-3 using chaotic 2D-PWC, which corresponds to a 28.6% usable bandwidth extension compared with that without using PWC. It is also shown that an increasing number of fluorescent fiber bundles in each antenna consistently leads to a remarkable improvement in BER performance.