Omni-resonant optical micro-cavity

Abstract

Optical cavities transmit light only at discrete resonant frequencies, which are well-separated in micro-structures. Despite attempts at the construction of planar ‘white-light cavities’, the benefits accrued upon optically interacting with a cavity – such as resonant field buildup – have remained confined to narrow linewidths. Here, we demonstrate achromatic optical transmission through a planar Fabry-Pérot micro-cavity via angularly multiplexed phase-matching that exploits a bio-inspired grating configuration. By correlating each wavelength with an appropriate angle of incidence, a continuous spectrum resonates and the micro-cavity is rendered transparent. The locus of a single-order 0.7-nm-wide resonance is de-slanted in spectral-angular space to become a 60-nm-wide achromatic resonance spanning multiple cavity free-spectral-ranges. The result is an ‘omni-resonant’ planar micro-cavity in which light resonates continuously over a broad spectral span. This approach severs the link between the resonance bandwidth and the cavity-photon lifetime, thereby promising resonant enhancement of linear and nonlinear optical effects over broad bandwidths in ultrathin devices.

Doubling the Near‐Infrared Photocurrent in a Solar Cell via Omni‐Resonant Coherent Perfect Absorption

“…[11,[14][15][16] Unavoidably, resonant enhancements within an optical cavity are harnessed over only narrow bandwidths as a result of the fundamental link between the cavity-photon lifetime and the resonant linewidth. [17] Here, we demonstrate that an omni-resonance scheme [18,19] can extend CPA continuously over a broad spectral bandwidth, thereby rendering this coherent-enhancement arrangement relevant for solar conversion applications. By severing the link between the cavity-photon lifetime and the resonant bandwidth, omni-resonance leads to the emergence of "achromatic" resonances [18] that can help deliver coherently enhanced broadband absorption.…”

“…The back‐reflector and front mirror define an asymmetric planar Fabry–Pérot cavity designed to realize the conditions for CPA. [ 12 ] However, because the complete absorption associated with CPA is achieved in the solar cell only on resonance (all other wavelengths reflect back from the cavity), we exploit the phenomenon of omni‐resonance [ 18 ] to extend CPA to a broad continuous spectral band. Making use of a light preconditioning system that endows broadband radiation incident on the CPA cavity with judicious angular dispersion, wavelengths across a continuous omni‐resonant bandwidth are fully absorbed, thereby enhancing the EQE of the solar cell and boosting the photocurrent.…”

“…[20][21][22][23][24][25] Instead, incident light is preconditioned using an alignment-free optical arrangement that assigns to each wavelength an appropriate angle of incidence. [18,19] In effect, we introduce into the incident field angular dispersion that is equal in magnitude but opposite in sign to that of the cavity. Consequently, angular dispersion cancellation allows all wavelengths within a selected band-that may extend over multiple free spectral ranges of the cavity-to resonate simultaneously, resulting in continuous-wavelength CPA and a concomitant boost in the external quantum efficiency (EQE).…”

“…Here, we demonstrate that an omni‐resonance scheme [ 18,19 ] can extend CPA continuously over a broad spectral bandwidth, thereby rendering this coherent‐enhancement arrangement relevant for solar conversion applications. By severing the link between the cavity‐photon lifetime and the resonant bandwidth, omni‐resonance leads to the emergence of ”achromatic” resonances [ 18 ] that can help deliver coherently enhanced broadband absorption.…”

“…Here, we demonstrate that an omni‐resonance scheme [ 18,19 ] can extend CPA continuously over a broad spectral bandwidth, thereby rendering this coherent‐enhancement arrangement relevant for solar conversion applications. By severing the link between the cavity‐photon lifetime and the resonant bandwidth, omni‐resonance leads to the emergence of ”achromatic” resonances [ 18 ] that can help deliver coherently enhanced broadband absorption. We realize this effect in a hydrogenated amorphous silicon (a‐Si:H) PIN‐diode solar cell incorporated into an unpatterned asymmetric planar Fabry–Pérot cavity produced via standard deposition technology, and is thus scalable in principle to large areas.…”