Light trapping and absorption optimization in certain thin-film photonic crystal architectures

摘要: We demonstrate two orders of magnitude enhancement light absorption in certain thin-film photonic crystal (PC) architectures due to strong resonances arising from parallel interface refraction (PIR). This anomalous type is acutely negative and usually out the plane incidence. Over a wide range frequencies, impinging on idealized two-dimensional (2D) crystals, over cone at least 20\ifmmode^\circ\else\textdegree\fi{} off-normal directions, couples Bloch modes propagating nearly thin-film--to--air interface. For realistic three-dimensional PC films cubic symmetry, synthesized by photoelectrochemical etching, PIR effect persists spectral 15% relative center frequency within 50\ifmmode^\circ\else\textdegree\fi{} incident angles, normal film. leads anomalously long optical path lengths dwell times before beam exits thin near continuum high-quality-factor resonances, associated with ``transverse slow modes'' high electromagnetic density states, can be much more effective for trapping absorbing than that previously reported longitudinal slow-group-velocity effects. The general found specific ranges both 2D 3D crystals or other appropriate symmetries. In presence weak backbone, energy conversion interpreted using simple temporal mode-coupling model. It shown optimized when structural quality factor (in absence absorption) transverse comparable $\ensuremath{\omega}{\ensuremath{\tau}}_{\mathrm{abs}}$, where $\ensuremath{\omega}$ ${\ensuremath{\tau}}_{\mathrm{abs}}$ time scale film material. Quantitative numerical results harvesting efficiency are obtained finite-difference time-domain simulations wave field. small amounts fabrication-related disorder introduce additional broaden existing thereby improving overall broadband wide-acceptance-angle light.