Experimental Demonstration of a 100-Gbit/s 16-QAM Free-Space Optical Link Using a Structured Optical Bottle Beam to Circumvent Obstructions

We experimentally demonstrate a free-space optical (FSO) communication link using an optical bottle beam to help circumvent obstructions. At the transmitter, an optical bottle beam is generated by spatially structuring a Gaussian beam with a transmitter beam diameter of 7 mm. During propagation, the energy of the bottle beam evolves in a three-dimensional (3-D) shell which creates a bottle-like low-intensity region, allowing the beam to circumvent an obstruction located inside this region. Subsequently, the beam evolves back to its original shape and propagates in its original direction. In our demonstration, we use a 100-Gbit/s, 16 quadrature amplitude modulation (16-QAM) data signal. Experimental results show that a bottle beam with a bottle size of 5 mm could help circumvent a circle-shaped obstruction with a diameter of similar to 4.5 mm and suffers similar to 10-dB less obstruction-induced power penalty as compared to a Gaussian beam. Additionally, we experimentally tailor the size and location of the bottle by changing the structuring pattern at the transmitter. Results after tailoring show that: (i) the beam with a larger bottle size could circumvent a larger obstruction but suffers more power loss when using a limited-size receiver aperture, and (ii) the location of the bottle in the propagation direction could be tuned to circumvent an obstruction more optimally at varying locations as compared to the case where the locations of the bottle and obstruction are not matched.

Automated summary

We experimentally demonstrate the potential application of using an optical bottle beam to circumvent obstructions in free-space optical communication. The experimental results show that the bottle beam has less power loss caused by obstructions compared to Gaussian beams, indicating its superiority in practical scenarios.