Color Converted White Light-Emitting Diodes With 637.6 MHz Modulation Bandwidth

Abstract

High bandwidth GaN-based white light-emitting diode (LED) was fabricated using GHz bandwidth blue LED chip combined with CdSe/ZnS semiconductor quantum dots (QDs). The maximum optical power of the blue LED chip can reach 7.2 mW. By changing the optical power ratio of the LED chip to the white LED, we have investigated the modulation properties and established a frequency response function of QD-converted white LED. The behaviors of the measured and simulated bandwidths using the function are in good agreement with each other. After optimizing the optical power ratio and decreasing the chip carrier lifetime, the 637.6 MHz bandwidth of QD-converted white LED was achieved, which can support 675 Mb/s real-time non-return-to-zero on-off-keying signal at a low bit error rate of 4.35 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> without optical filters. Our findings can help to design high bandwidth white LEDs for visible light communication applications in free space.