Strong Omnidirectional and Broadband Absorption of the Solar Light with Arrays of Submicrometer-Scaled Compound Parabolic Light Concentrators

摘要

Efficient omnidirectional broadband absorption is important to various applicationsinvolving the harvest of the solar spectrum. The optical absorptiondependency on oblique illumination in arrays of submicrometer-scaled compoundparabolic concentrators (CPCs) is examined. For a non-optimized CPC array, thebroadband absorption is ≈30% higher than that of a nanopillar (NP) array thatis corrected for the absorption of the solar light for an angle-of-illumination rangeof 0°-80°. It is shown that enhanced absorptivity of CPC arrays, relative to theoptically corrected NP array, is due to the repressed transmission for bothtransverse electric and transverse magnetic illumination. It is determined thatthe superior omnidirectional broadband absorption of a CPC array is due to strong“light bending”; in the CPC array, the optical intensity is predominantly distributedlaterally, whereas in the NP array, the optical intensity is mainly directed inthe vertical direction. It is shown that for the CPC array, the intensity lateralcomponents are up to 80% higher than the lateral components in the NP array.Finally, the CPC array omnidirectional broadband absorption is governed bysubstantial light bending, which induces competent excitation of variousasymmetric photonic states.