Cheap, 9 Gbps Last Mile Free-space Optical Data Communication

Miniaturized FSO breakthrough unlocks high-speed wireless communication anywhere Researchers from Nanjing University (NJU) have developed a miniaturized FSO system that promises to revolutionize high-speed wireless communication. As reported in the Gold Open Access journal Advanced Photonics Nexus (APNexus), this remarkable system achieved an astonishing communication bandwidth of 9.16 gigabits per second (Gbps) over a 1-kilometer (km) link. What sets it apart is that it accomplishes such high FSO performance using readily available commercial fiber optical communication transceiver modules (no need for optical amplification).

The core of this miniaturized FSO system comprises a pair of FSO devices. Each FSO device is compact, measuring just 45 cm × 40 cm × 35 cm, with a weight of 9.5 kilograms and a power consumption of approximately 10 watts. Each houses an optical transceiver module, an acquisition, pointing, and tracking (APT) device, and its control electronics, all safely sealed within a box for rugged outdoor operation. The APT device stands out with its low-diffraction optical design and a highly efficient 4-stage closed-loop feedback control system.

The FSO system exhibits remarkable tracking capabilities, through the integration of multiple sensors and sophisticated algorithms, which enable automatic, fast, and highly accurate acquisition and fine tracking in just 10 minutes. This precision keeps the tracking error within an impressive 3 microradians (μrad), resulting in a low average link loss of just 13.7 decibels (dB) over the 1-km link. Such precision also eliminates the need for optical amplification. Remarkably, the FSO system can achieve bidirectional data rates averaging 9.27 Gbps over the 1-km link, using only commercial transceiver modules.

Xie notes that the effective distance of 1 km may be extended. His team also tested the optical links at up to 4 km, where the average loss increased to 18 dB – likely due to a foggy test environment. “With better weather conditions and optical amplification, longer FSO can be expected,” Xie concludes.

High-speed free-space optical communication using standard fiber communication components without optical amplification, Adv. Photon. Nexus

Free-space optical communication (FSO) can achieve fast, secure, and license-free communication without physical cables, providing a cost-effective, energy-efficient, and flexible solution when fiber connection is unavailable. To achieve FSO on demand, portable FSO devices are essential for flexible and fast deployment, where the key is achieving compact structure and plug-and-play operation. Here, we develop a miniaturized FSO system and realize 9.16 Gbps FSO in a 1 km link, using commercial single-mode-fiber-coupled optical transceiver modules without optical amplification. Fully automatic four-stage acquisition, pointing, and tracking systems are developed, which control the tracking error within 3 μrad, resulting in an average link loss of 13.7 dB. It is the key for removing optical amplification; hence FSO is achieved with direct use of commercial transceiver modules in a bidirectional way. Each FSO device is within an overall size of 45 cm × 40 cm × 35 cm, and 9.5 kg weight, with power consumption of ∼10 W. The optical link up to 4 km is tested with average loss of 18 dB, limited by the foggy test environment. With better weather conditions and optical amplification, longer FSO can be expected. Such a portable and automatic FSO system will produce massive applications of field-deployable high-speed wireless communication in the future.






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