450-nm GaN laser diode enables high-speed visible light communication with 9-Gbps QAM-OFDM

Abstract

A TO-38-can packaged Gallium nitride (GaN) blue laser diode (LD) based free-space visible light communication (VLC) with 64-quadrature amplitude modulation (QAM) and 32-subcarrier orthogonal frequency division multiplexing (OFDM) transmission at 9 Gbps is preliminarily demonstrated over a 5-m free-space link. The 3-dB analog modulation bandwidth of the TO-38-can packaged GaN blue LD biased at 65 mA and controlled at 25°C is only 900 MHz, which can be extended to 1.5 GHz for OFDM encoding after throughput intensity optimization. When delivering the 4-Gbps 16-QAM OFDM data within 1-GHz bandwidth, the error vector magnitude (EVM), signal-to-noise ratio (SNR) and bit-error-rate (BER) of the received data are observed as 8.4%, 22.4 dB and 3.5 × 10(-8), respectively. By increasing the encoded bandwidth to 1.5 GHz, the TO-38-can packaged GaN blue LD enlarges its transmission capacity to 6 Gbps but degrades its transmitted BER to 1.7 × 10(-3). The same transmission capacity of 6 Gbps can also be achieved with a BER of 1 × 10(-6) by encoding 64-QAM OFDM data within 1-GHz bandwidth. Using the 1.5-GHz full bandwidth of the TO-38-can packaged GaN blue LD provides the 64-QAM OFDM transmission up to 9 Gbps, which successfully delivers data with an EVM of 5.1%, an SNR of 22 dB and a BER of 3.6 × 10(-3) passed the forward error correction (FEC) criterion.

Performance evaluation of underwater wireless optical communications links in the presence of different air bubble populations

“…Using efficient and low-cost light sources such as light-emitting diodes (LEDs) [1] and laser diodes (LD) [2] in the low absorption 400-550 nm window of the electromagnetic spectrum in seawater, UWOC can provide orders of magnitude more bandwidth and achieve much higher data rates for short and moderate ranges (<100 m) [3,4]. In UWOC links, the primary factors that degrade system performance are absorption, scattering, and turbulence.…”

Laser based underwater communication systems

“…In order to simulate the effects of increased water turbidity in a laboratory, Maalox antacid was used as a scattering agent in addition to fresh water. It consists mostly of Mg(OH) 2 and Al(OH) 3 with a very similar volume scattering function (VSF) to that of seawater. The extracted attenuation coefficient value for clear water was 1.2 m -1 and the communication link was established over a distance of 1 m, sufficient to investigate the effects of scattering on the laser beam even for high concentrations of Maalox (4 litres of Maalox in 8000 litres of water).…”

“…Laser based VLC with direct NRZ-OOK has shown data rates of up to 4 Gbit/s [1,2] and by taking advantage of more complex modulation schemes like OFDM it is possible to reach 9 Gbit/s [3]. We experimentally demonstrate high data rates over a free space link, NRZ-OOK (4.7 Gbit/s) and 64-QAM OFDM (11.9 Gbit/s), using direct modulation schemes of a 450 nm InGaN laser diode and a receiver with an optical -3 dB bandwidth of 1.4 GHz.…”

Low modulation bias InGaN-based integrated EA-modulator-laser on semipolar GaN substrate

“…The development of InGaN based laser diodes (LDs) [1] for visible light communication [2] has recently attracted increasing attention. The common feature of the devices demonstrated so far has been the implementation of direct current modulation of laser diodes [3][4][5].…”