GaN-based miniaturized cyan light-emitting diodes on a patterned sapphire substrate with improved fiber coupling for very high-speed plastic optical fiber communication

We demonstrate the performance of a novel cyan light-emitting diode (LED) on a patterned sapphire (PS) substrate as a light source for plastic optical fiber (POF) communications with the central wavelength at 500 nm. To further enhance the external quantum efficiency (EQE) and output power of this miniaturized high-speed LED, a LED with a PS substrate is adopted. Furthermore, by greatly reducing the number of active In _xGa _1-xN/GaN multiple quantum wells (MQWs) to four and minimizing the device active area, we can achieve a record-high electrical-to-optical (E-O) bandwidth (as high as 400 MHz) among all the reported high-speed visible LEDs under a very small dc bias current (40 mA). The fiber coupling efficiency has been improved in 4 dB using lens with a 500-μm diameter mounted on the LED chip. Thus, the maximum fiber-coupled power was-2.67 dBm at the bias current of 40 mA. The 1.07-Gb/s data transmissions over a 50-m SI-POF fiber have been successfully demonstrated using this device at the bias current of 40 mA.