The
light-emitting diode (LED) is among promising candidates of
light sources in visible light communication (VLC); however, strong
internal polarization fields in common c-plane LEDs,
especially green LEDs, result in low frequency and limited transmission
performance. This study aims to overcome the limited 3-dB bandwidth
of long-wavelength InGaN/GaN LEDs. Thus, semipolar (20–21)
micro-LEDs (μLEDs) were fabricated through several improved
approaches on epitaxy and chip processes. The μLED exhibits
a 525 nm peak wavelength and good polarization performance. The highest
3-dB bandwidth up to 756 MHz and 1.5 Gbit/s data rate was achieved
under a current density of 2.0 kA/cm2. These results suggest
a good transmission capacity of green semipolar (20–21) μLEDs
in VLC applications.
We propose and implement a high-bandwidth white-light visible light communication (VLC) system accomplishing data rate of 2.805 Gbit/s utilizing a semipolar blue micro-LED. The system uses an InGaN/GaN semipolar (20-21) blue micro-LED to excite yellow phosphor film for high-speed VLC. The packaged 30 μm 2 × 4 blue micro-LED array has an electrical-to-optical (EO) bandwidth of 1042.5 MHz and a peak wavelength of 447 nm. The EO bandwidth of the white-light VLC system is 849 MHz. Bit error rate (BER) of 2.709 × 10−3 meeting the pre-forward error correction (FEC) threshold is accomplished by employing a bit and power loaded orthogonal frequency division multiplexing (OFDM) signal. The proposed white-light VLC system employs simple and inexpensive yellow phosphor film for white-light conversion, complex color conversion material is not needed. Besides, no optical blue filter is employed in the white-light VLC system. The fabrication of the InGaN/GaN semipolar (20-21) blue micro-LED is discussed, and its characteristics are also evaluated.
In this study, we present a high-efficiency InGaN red micro-LED fabricated by the incorporation of superlattice structure, atomic layer deposition passivation, and a distributed Bragg reflector, exhibiting maximum external quantum efficiency of 5.02% with a low efficiency droop corresponding to an injection current density of
112
A
/
cm
2
. The fast carrier dynamics in the InGaN is characterized by using time-resolved photoluminescence, which is correlated to a high modulation bandwidth of 271 MHz achieved by a
6
×
25-μm-sized micro-LED array with a data transmission rate of 350 Mbit/s at a high injection current density of
2000
A
/
cm
2
. It holds great promise for full-color micro-displays as well as high-speed visible light communication applications based on monolithic InGaN micro-LED technologies.
We propose and demonstrate using signal pre-distortion and equalization schemes for increasing the data rate of the white-light LED communication system. Bit-error-rate of <10 -10 at 10-Mb/s operation was achieve using 1-MHz bandwidth white-light LED.
A record 4.343 Gbit/s green color micro-light-emitting-diode (μ-LED) based visible-light-communication (VLC) is demonstrated. We designed and fabricated the InGaN/GaN μ-LED array with modulation bandwidth > 1.1 GHz. The micro-LED was grown on semipolar (20-21) orientation, which could offer higher modulation bandwidth at a lower current density.
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