Engineering of Hybrid Nanoporous Anodic Alumina Photonic Crystals by Heterogeneous Pulse Anodization

Abstract

In this study, we present an advanced nanofabrication approach, so-called ‘heterogeneous pulse anodization’ (HPA), in which galvanostatic stepwise and apodized sinusoidal pulse anodizations are combined in a single process. This novel anodization method enables the precise optical engineering of the characteristic photonic stopbands (PSBs) of nanoporous anodic alumina photonic crystals (NAA-PCs). The resulting structures are hybrid PCs (Hy-NAA-PCs) composed of distributed Bragg reflectors (DBRs) and apodized gradient-index filters (APO-GIFs) embedded within the same PC structure. The modification of various anodization parameters such as anodization period, relative and total anodization time, structural arrangement of PCs within Hy-NAA-PCs, and pore widening time allows the fine-tuning of the PSBs’ features (i.e. number, position and bandwidth of central wavelength) across the spectral regions. The effects of these fabrication parameters are systematically assessed, revealing that the positions of the characteristic transmission bands of Hy-NAA-PCs are highly controllable. Our study provides a comprehensive rationale towards the development of unique Hy-NAA-PCs with controllable optical properties, which could open new opportunities for a plethora of applications.

Recent Advances in Nanoporous Anodic Alumina: Principles, Engineering, and Applications

“…To provide overview of many functionalities discussed in Sections 4.1-4.7, they are gathered in the Table 2. [190] Gradient-index filters [191] Distributed Bragg reflectors [192] Optical bandpass filters [193] Human protein heavy ions real-time interaction monitoring [194] Tailoring of optical properties with pulse anodization [149] Design of phase shift defect in effective refractive index [195] Hybrid distributed DBRs and apodized GIF photonic structure [196] Characterization of thermotropic ferroelectric liquid crystals confined in the NAA [197][198][199] Glass transition of discotic liquid crystals in one-dimensional fluid [200] Adjustable optical anisotropy by self-assembly of liquid crystals confined in porous structure [201] Sensors NAA template-assisted fabrication of chromium substrate for SERS detection of heavy ions in aqueous solutions [202] Au NPs array on NAA for SERS detection of hemoglobin [203] Controlled fabrication of periodic plasmonic dimer arrays for SERS [204] Graphene-NAA composite for SERS sensing [205] Label-free optical sensor based on interferometric reflectance spectroscopy for TNF-α detection [206] NAA-based interferometer for copper sensing [207] In vivo nanotubes nanotoxicity study on murine model […”

Rational Management of Photons for Enhanced Photocatalysis in Structurally-Colored Nanoporous Anodic Alumina Photonic Crystals

“…4 NAA-PCs have distinctive PSBs, the features of which can be readily tuned across the spectral regions by engineering the effective medium of NAA in a multi-dimensional fashion, through various anodization approaches. 45,[47][48][49][50][51][52] These NAA-PC platforms include optical microcavities 47,48 , distributed Bragg reflectors 5 (DBR) 45,49 , linear variable bandpass filters 50 , gradient-index filters 51 , and hybrid PCs 52 . These PC structures provide new opportunities to rationally utilize the "slow photon" effect to attain an efficient management of photons at the nanoscale for photocatalytic applications.…”

Nanoporous Anodic Alumina Photonic Crystals for Optical Chemo- and Biosensing: Fundamentals, Advances, and Perspectives

“…Transmission spectra of NAA-GIFs are characterized by a narrow, well-defined, and spectrally tunable PSB, which is a result of a smooth modulation of effective refractive index driven by the SPA profile. Apo-NAA-DBRs and Apo-NAA-GIFs are produced by apodizing STPA and SPA anodization profiles, respectively [ 78 , 79 , 80 , 81 ]. The characteristic PSB of these NAA-PCs is similar to that of their nonapodized counterparts but with much narrower width due to the apodization of their effective medium.…”

“…The characteristic PSB of these NAA-PCs is similar to that of their nonapodized counterparts but with much narrower width due to the apodization of their effective medium. Several studies have demonstrated the successful application of different apodization functions to STPA and SPA profiles to engineer the photonic features of NAA-DBRs and NAA-GIFs [ 78 , 79 , 80 , 81 ]. NAA-μCVs are a class of NAA-PCs that confine light to small volumes by resonant recirculation of electromagnetic waves [ 82 , 83 , 84 ].…”

“…The optical spectrum of these NAA-PCs has a characteristic PSB when light flows transversally through the NAA-FPIs’ structure, which is established by the interpore distance (i.e., lattice constant) and porosity (i.e., nanopore diameter) [ 46 , 47 , 48 , 49 ]. NAA-BPFs are PC structures that allow the transmission of a specific portion of the light spectrum in a selective manner while impeding the pass of light of all other wavelengths [ 79 , 86 ]. NAA-BPFs can be classified into three categories according to the range of allowed wavelengths: (i) longpass filters, which allow the transmission of light of long wavelengths, (ii) shortpass filters, which allow the pass of light of short wavelengths, and (iii) bandpass filters, which allow the transmission of a band of wavelengths while blocking the pass of light of shorter and longer wavelengths.…”