Broadband antireflective glasses with subwavelength structures using randomly distributed Ag nanoparticles.

We demonstrate broadband antireflective glasses with subwavelength structures (SWSs) using randomly distributed Ag nanoparticles. Ag nanoparticles formed by a thermal dewetting process were used as an etch mask for dry etching to fabricate antireflective SWSs on the glass surface. The size and shape of Ag nanoparticles are changed by the different thickness of the Ag thin film. The morphology of SWSs fabricated by using the Ag thin films is well consistent with that of the Ag nanoparticles. The single-side SWS integrated glass exhibits improved transmittance of approximately 96% at 750 nm due to the graded refractive index profiles, while the transmittance is only approximately 92.5% for the flat surface. To reduce Fresnel reflection at the other side of the glass substrate, the SWSs with optimized Ag film thickness and dry etching conditions are formed on both sides of the glass. The dual-side SWS integrated glass show an average transmittance of approximately 97.5% in a wavelength range of 350-750 nm. Transmission band shrinkage effects of the SWS integrated glass are also observed with increased average size of the Ag nanoparticles.

Multifunctional light escaping architecture inspired by compound eye surface structures: From understanding to experimental demonstration.

We present bioinspired artificial compound eye surface structures that consist of antireflective subwavelength structures (SWSs) on hexagonally patterned microstructures (MSs), for the purpose of efficient light escaping inside light-emitting materials/devices. Theoretical understanding and geometrical optimization of SWSs on MSs are described together with rigorous coupled-wave analysis. As a proof of this concept, AlGaInP red light-emitting diodes (LEDs) with SWS/MSs were fabricated, and a light output power enhancement of 72.47% was achieved as compared to that of conventional LEDs. The artificial compound eye structures are not limited to LEDs, and the fabrication process is compatible with most semiconductor device manufacturing processes; hence, this concept opens up new possibilities for improving the optical performance of various optoelectronic device applications.