Free-standing guided-mode resonance band-pass filters: from 1D to 2D structures

Abstract

We study experimentally and theoretically band-pass filters based on guided-mode resonances in free-standing metal-dielectric structures with subwavelength gratings. A variety of filters are obtained: polarizing filters with 1D gratings, and unpolarized or selective filters with 2D gratings, which are shown to behave as two crossed-1D structures. In either case, a high transmission (up to ≈ 79 %) is demonstrated, which represents an eight-fold enhancement compared to the geometrical transmission of the grating. We also show that the angular sensitivity strongly depends on the rotation axis of the sample. This behavior is explained with a detailed description of the guided-mode transmission mechanism.

Solution‐Based Micro‐ and Nanoscale Metal Oxide Structures Formed by Direct Patterning for Electro‐Optical Applications

“…Due to the high refractive index ( n ) and transparency, MOs have many applications in optical devices, such as gratings, photonic crystals, filters, antireflection layers, and biochemical sensors . Among all the available MOs, TiO 2 is particularly interesting.…”

Metal–dielectric bi-atomic structure for angular-tolerant spectral filtering

“…More recently, a new kind of bandpass guided-mode resonance filter based on a metallic grating deposited on a single free-standing dielectric layer has been studied [9,10]. These filters are particularly well suited for infrared multispectral imaging applications [11,12] in terms of mechanical robustness, rejection efficiency, and quality factor.…”

“…To circumvent this problem in the case of all-dielectric guided-mode resonance structures, Lemarchand et al have introduced a bi-atomic structure and demonstrated an increase of the angular tolerance without modifying the spectral lineshape [13,15]. However, this concept cannot be directly transposed to the metaldielectric structures of the papers [9,10]. Indeed, in this latter case, the nonradiative losses dominate and limit the influence of the grating shape.…”

“…Figure 1(b) shows the transmission spectrum computed with a B-splines modal method [16]. (In our calculations the refractive index of SiN x is fixed at two; a Drude model is used for the refractive index of gold: ε m λ 1 − λ p ∕λ iγλ p ∕λ −1 with λ p 159 nm and γ 0.0077) It is compared to the transmission spectrum of a similar structure with only one grating on one side of the waveguide layer [9,10]. The rejection efficiency of the two-grating structure [ Fig.…”

“…The spectral shift between the two transmission peaks is due to the slight modification of the eigenmode k g in the SiN x layer, which alters the phase-matching condition k 1 x k g . However, both structures have a low angular tolerance, as shown in [9,10] and below.…”