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Abstract Here, a wavelength‐specific photo‐thermoelectric (PTE) device is reported that achieves narrowband optical absorption and thermoelectric conversion functions using a stack of thin films on a grating‐patterned substrate. Conventional PTE devices are broadband with the absorption of electromagnetic radiation from ultraviolet to terahertz. There are demands for PTE devices that can exhibit narrowband response at a desired wavelength. Here, the narrowband PTE device consists of a photonic crystal (PC) filter with metal cladding and a thin‐film thermocouple. The PC‐PTE design is investigated numerically to illustrate the underlying energy conversion mechanism. The device is fabricated using nanoreplica molding followed by coating of thin films. The fabricated metal‐cladding PC resonator exhibits a narrowband optical absorption with a resonant absorption coefficient of 85.4% and full‐width‐half‐maximum of 14.8 nm in the visible wavelength range. The PTE measurements show that the thermoelectric output is sensitive to the coupling of incident light and guided‐mode resonance modes. Illuminated under the resonant condition, the PTE device exhibits a responsivity and noise equivalent power of 0.26 V W−1and 7.5 nW Hz−1/2, respectively. This PC‐PTE technology has the unique attributes of narrowband detection, large surface area, and low cost for the potential application in sensors, optical spectroscopy, and imaging.
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Photonic Crystal Enhanced Microscopy on a 2D Photonic Crystal Surface
Abstract Digital‐resolution biosensing based on resonant reflection from photonic crystals (PC) has demonstrated significant potential for detection of proteomic and genomic biomarkers in serology, infectious disease diagnostics, and cancer diagnostics. An important intrinsic characteristic of resonant metamaterial surfaces is that enhanced electromagnetic fields are not uniformly distributed, resulting in spatially variable light‐matter interactions with nanoparticle tags that signal the presence of biomarker molecules. In this work, the spatial uniformity of resonantly enhanced, surface‐confined electromagnetic fields of a 1D PC is compared with a 2D PC with fourfold symmetry. When illuminated with unpolarized light, the simultaneously excited electromagnetic fields of transverse electric and transverse magnetic modes of the 2D PC present equally strong but complementary spatial distribution, leading to a >100% increased average near‐field intensity accompanied with a >50% compressed standard deviation compared to the 1D PC. Utilizing Photonic Resonator Absorption Microscopy (PRAM) to experimentally measure the absorption uniformity of ≈80 nm gold nanoparticles distributed upon the PC surface, a >100% improvement of the signal uniformity is observed when using the 2D PC. Overall, improvement in AuNP detection contrast, uniformity, and point spread function is demonstrated by PRAM performed upon a 2D PC surface.
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- Award ID(s):
- 2232681
- PAR ID:
- 10640888
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 10
- Issue:
- 6
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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