1 Gbps free-space deep-ultraviolet communications based on III-nitride micro-LEDs emitting at 262 nm

The low modulation bandwidth of deep ultraviolet (UV) light sources is considered as the main reason limiting the data transmission rate of deep UV communications.Here, we present high-bandwidth IIInitride micro-light emitting diodes (µLEDs) emitting in the UV-C region and their applications in deep UV communication systems.The fabricated UV-C µLEDs with 566 µm 2 emission area produce an optical power of 196 µW at the 3400 A/cm 2 current density.The measured 3-dB modulation bandwidth of these µLEDs initially increases linearly with the driving current density and then saturates as 438 MHz at a current density of 71 A/cm 2 , which is limited by the cut-off frequency of the commercial avalanche photodiode used for the measurement.A deep UV communication system is further demonstrated.By using the UV-C µLED, up to 800 Mbps and 1.1 Gbps data transmission rates at bit error ratio of 3.8 × 10 -3 are achieved assuming on-off-keying and orthogonal frequency division multiplexing modulation schemes, respectively.