Abstract
Monolithic integration of red, green, and blue (RGB) LEDs is crucial for white light visible light communications (VLC), display technology, and general illumination but is intrinsically limited by the fundamental differences between the InGaN and AlGaInP epitaxial material systems typically used for visible wavelength emission. Increasing the indium content in traditional c-plane InGaN/GaN to achieve longer wavelength LEDs enhances the piezoelectric-induced polarization resulting in a low quantum efficiency and long radiative lifetimes. These issues can be resolved by growing along a nonpolar or semipolar orientation. This paper demonstrates the feasibility of the (11–22) semipolar LEDs for long-wavelength VLC with an additional capability of monolithic integration to produce a single white light RGB chip. Based on our high-performance semipolar InGaN/GaN LEDs, we report record data transmission rates of 4.22 Gb/s, 3.72 Gb/s, and 336 Mb/s under the forward error correction (FEC) threshold standard for reliable communication for our green (515 nm), yellow (550 nm), and amber (600 nm) semipolar LEDs using adaptively bit-loaded DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM).
Highlights
Visible light communication (VLC) is an emerging wireless communication technology, providing a complementary technology to radio-frequency (RF)-based Wi-Fi/5G
To meet the material challenges, our group has established a number of cost-effective approaches to achieve high-quality semipolar (11−22) GaN grown on m-plane sapphire, demonstrating very bright semipolar InGaN LEDs covering a wide wavelength range up to amber.[19−21] Very recently, we have reported our frequency response measurements on these high-performance semipolar LEDs, exhibiting a record modulation bandwidth of 540, 350, and 140 MHz all with a broad area on our semipolar green, yellow, and amber LEDs, respectively.[22]
Given the high performance of these semipolar LEDs with long emission wavelengths and the record modulation bandwidth, which we have achieved on these semipolar LEDs, it is worth exploring the upper limit on the data transmission rate achievable on these long-wavelength semipolar LEDs, which is crucial for eventually achieving a monolithically integrated white LEDs for both solidstate lighting (SSL) and VLC
Summary
Visible light communication (VLC) is an emerging wireless communication technology, providing a complementary technology to radio-frequency (RF)-based Wi-Fi/5G. To meet the material challenges, our group has established a number of cost-effective approaches to achieve high-quality semipolar (11−22) GaN grown on m-plane sapphire, demonstrating very bright semipolar InGaN LEDs covering a wide wavelength range up to amber.[19−21] Very recently, we have reported our frequency response measurements on these high-performance semipolar LEDs, exhibiting a record modulation bandwidth of 540, 350, and 140 MHz all with a broad area (with a typical dimension of 330 × 330 μm2) on our semipolar green, yellow, and amber LEDs, respectively.[22] This is the report on modulation bandwidth for the longest wavelength III-nitride LEDs. Given the high performance of these semipolar LEDs with long emission wavelengths and the record modulation bandwidth, which we have achieved on these semipolar LEDs, it is worth exploring the upper limit on the data transmission rate achievable on these long-wavelength semipolar LEDs, which is crucial for eventually achieving a monolithically integrated white LEDs for both SSL and VLC. Single-LED devices are demonstrated here to show the feasibility of the long-wavelength VLC performance of the (11−22) semipolar LEDs
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