Bio-Inspired Broadband Optical Cavity System for Ultra-Thin Devices

Abstract

Researchers at the University of Central Florida have developed an apparatus and methods for achieving omniresonant broadband coherent perfect absorption (CPA) in a structure. With the ability to provide maximum absorption across extended bandwidths, the invention enables achromatic optical absorption (omniresonance spanning greater than 50 nm, CPA). Existing technologies require modifying the cavity by inserting a new material or structure with a sculpted dispersion profile. Thus, those technologies only support the exploration of macroscopic white-light cavities.

The UCF invention enables 100% effective optical absorption—regardless of the material from which it is constructed—over a large, continuous bandwidth (omniresonance) in ultrathin devices. The inspriation for this design is the reverse-color diffraction observed in the wings of the Moon Satyr butterfly, Pierella luna, enabling “anomalous diffraction”. Example applications include the following:

• Achieving flat spectral sensitivity for photodetectors
• Enabling cost-effective harnessing of infrared solar energy
• White-light micro-lasers using only planar technology
• Other broadband resonantly enhanced optical effects

Technical Details

The UCF invention provides a structure, systems and methods for achieving omniresonant broadband coherent perfect absorption (CPA) in a planar Fabry-Pérot microcavity. It employs angularly multiplexed phase-matching that exploits a bioinspired grating configuration. By assigning each wavelength to an appropriate angle of incidence, the microcavity can absorb with continuous spectral range. For example, the linewidth of a single-order 0.7 nm wide resonance is de-slanted in spectral-angular space to become a 70 nm wide achromatic resonance spanning multiple cavity-free spectral ranges.

Figure 1 illustrates the following: (a) Using a ‘black-box system’ correlating ? with ?, a planar micro-cavity is made transparent. The inverse is placed after the cavity to restore the original beam. (b) Solid curves are target correlations between ? and ? that help de-slant different resonant mode-orders in a planar micro-cavity. The dashed curve corresponds to the correlation imparted to a collimated broadband beam centered at ?c=550 nm that is incident normally on a planar surface grating having 1800 lines/mm. (c) Angular diffraction resulting from a planar surface grating parallel and (d) normal to the plane of a cavity. 

Figure 2 illustrates the following: (a) Measured spectral transmission of collimated light through the cavity with angle of incidence ? for both polarizations. The transmission is symmetric in ? for TE (H: horizontal) and TM (V: vertical) polarizations, so measurements for only positive ? are plotted. Inset is a schematic of the configuration. (b) Experimental setup. L1 and L2 are lenses, OSA: optical spectrum analyzer; see main text and Supplement 1 for details. Inset is a photograph of the resonator showing strong reflectivity in the visible (cavity sample diameter is 25 mm).

Partnering Opportunity

The research team is looking for partners to develop the technology further for commercialization.

Stage of Development

Proof of principle.

Benefit

Market Application

Publications

Omni-resonant optical micro-cavity, Scientific Reports 7, 10336 (2017). https://doi.org/10.1038/s41598-017-10429-4.