Abstract
Much interest has been paid to omnidirectional dielectric mirrors based on the 1-D dielectric multilayers because these are better than metal mirrors owing to their low optical loss, high reflectivity and high mechanical robustness. In these applications, the required position and width of the reflection band can be obtained by adjusting the layer thickness and refractive indices of the constituent materials. Here, the omnidirectional reflection characteristics of a 1-D PC formed by TiO2/SiO2 multi-quantum wells (MQW) are investigated in the visible region. It is demonstrated that the omnidirectional high reflector, formed by the proper line-up of four TiO2/SiO2 MQWs, covers the visible band approximately when the number of periodic layers of each quantum well reaches 12. This study can provide guidance in the design of an omnidirectional high reflector in the visible band. Key words: Omnidirectional reflector, photonic crystals, multi-quantum wells.
Highlights
In recent years, omnidirectional reflection i.e. nearly 100% reflectivity at all incident angles for both transverse electric (TE) and transverse magnetic (TM) modes by a periodic 1-D medium has much attention from various research groups of the field
The omnidirectional reflection characteristics of a 1-D photonic crystals (PCs) formed by TiO2/SiO2 multi-quantum wells (MQW) are investigated in the visible region
It is demonstrated that the omnidirectional high reflector, formed by the proper line-up of four TiO2/SiO2 MQWs, covers the visible band approximately when the number of periodic layers of each quantum well reaches 12
Summary
Omnidirectional reflection i.e. nearly 100% reflectivity at all incident angles for both transverse electric (TE) and transverse magnetic (TM) modes by a periodic 1-D medium has much attention from various research groups of the field. Fink et al (1998) and Winn et al (1998) firstly designed the omnidirectional reflection in 1-D photonic crystal and demonstrated it over a wavelength range from 10 to μm. A lattice consisting of 19 layers of Na3AlF6 and ZnSe was fabricated by Chigrin et al (1999a; b) and they observed the omnidirectional band gap in the frequency range 604.3 to 638.4 nm. Lee and Yao (2003) investigated different structures theoretically and experimentally for a realistic fabrication of 1-D photonic bandgap materials, exhibiting omnidirectional band gaps (OBGs) in 2003. The different materials used to fabricate 1-D PCs for OBGs in various frequency ranges are tellurium/polyethylene for infrared (Fink et al, 1998), TiO2/SiO2 (Valligatla et al, 2012) for near infrared (NIR) and TiO2/SiO2 (Lin et al, 2005) for visible light.
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