Divergence-tolerant resonant bandpass filters.

Bandpass filters based on subwavelength dielectric gratings are grounded in physical principles that are totally distinct from their thin-film counterparts. Ease in fabrication, design scalability, material sparsity, and on-chip integration compatibility makes them a promising alternative especially for long-wavelength applications. Here we demonstrate the interesting attribute of resonant bandpass filters of high angular stability for fully conical light incidence.

Unpolarized resonance grating reflectors with 44% fractional bandwidth.

There is immense scientific interest in the properties of resonant thin films embroidered with periodic nanoscale features. This device class possesses considerable innovation potential. Accordingly, we report unpolarized broadband reflectors enabled by a serial arrangement of a pair of polarized subwavelength gratings.

Properties of wideband resonant reflectors under fully conical light incidence.

Applying numerical modeling coupled with experiments, we investigate the properties of wideband resonant reflectors under fully conical light incidence. We show that the wave vectors pertinent to resonant first-order diffraction under fully conical mounting vary less with incident angle than those associated with reflectors in classical mounting. Therefore, as the evanescent diffracted waves drive the leaky modes responsible for the resonance effects, fully-conical mounting imbues reflectors with larger angular tolerance than their classical counterparts.

Single-layer optical bandpass filter technology.

Resonant periodic surfaces and films enable new functionalities with wide applicability in practical optical systems. Their material sparsity, ease of fabrication, and minimal interface count provide environmental and thermal stability and robustness in applications. Here, we report an experimental bandpass filter fashioned in a single patterned silicon layer on a quartz substrate.

Concurrent spatial and spectral filtering by resonant nanogratings.

Optical devices incorporating resonant periodic layers constitute an emerging technological area. Recent advances include spectral filters, broadband mirrors, and polarizers. Here, we demonstrate concurrent spatial and spectral filtering as a new outstanding attribute of this device class.

Mode-coupling mechanisms of resonant transmission filters.

We study theoretically modal properties and parametric dependence of guided-mode resonance bandpass filters operating in the mid- and near-infrared spectral domains. We investigate three different device architectures consisting of single, double, and triple layers based on all-transparent dielectric and semiconductor thin films. The three device classes show high-performance bandpass filter profiles with broad, flat low-transmission sidebands accommodating sharp transmission peaks with their efficiencies approaching 100% with appropriate blending of multiple guided modes.