Size- and current-density-controlled tunable wavelength in gan-based leds for potential dense wavelength-division multiplexing application

A micro-LED array device with hybrid pixel sizes from 30 μm~60 μm is designed and fabricated. A wavelength tunable range of 20 nm is obtained, which shows the device's potential as a tunable light source to enable DWDM technology for visible light communication applications. For example, superimposing the luminescent spectra of μLEDs by different combinations, a series of spectra and light intensity values can be obtained. In addition, the FWHM of the complex spectrum broadens from 16 nm to 45 nm. Considered from the aspect of general lighting, a broader FWHM can increase lighting quality. The tunable peak wavelength is controlled by micro-LED size and input current density. Underlying mechanisms are discussed. The structure parameters of the arrayed-μLED device can be further optimized to satisfy requirements on communications and general lighting.