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1. Heating Effects on Nanofabricated Plasmonic Dimers with Interconnects

   https://doi.org/10.1142/S0129156423500040  

   Raman, Rahul; Grasso, John; Willis, Brian G (December 2023, International Journal of High Speed Electronics and Systems)

   Plasmonic nanostructures with electrical connections have potential applications as new electro-optic devices due to their strong light–matter interactions. Plasmonic dimers with nanogaps between adjacent nanostructures are especially good at enhancing local electromagnetic (EM) fields at resonance for improved performance. In this study, we use optical extinction measurements and high-resolution electron microscopy imaging to investigate the thermal stability of electrically interconnected plasmonic dimers and their optical and morphological properties. Experimental measurements and finite difference time domain (FDTD) simulations are combined to characterize temperature effects on the plasmonic properties of large arrays of Au nanostructures on glass substrates. Experiments show continuous blue shifts of extinction peaks for heating up to 210°C. Microscopy measurements reveal these peak shifts are due to morphological changes that shrink nanorods and increase nanogap distances. Simulations of the nanostructures before and after heating find good agreement with experiments. Results show that plasmonic properties are maintained after thermal processing, but peak shifts need to be considered for device design. 

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2. 2D beam shaping via 1D spatial light modulator using static phase masks

   https://doi.org/10.1364/OL.419419  

   Whitehead, James_E_M; Ryou, Albert; Colburn, Shane; Zhelyeznyakov, Maksym; Majumdar, Arka (May 2021, Optics Letters)

   Many emerging, high-speed, reconfigurable optical systems are limited by routing complexity when producing dynamic, two-dimensional (2D) electric fields. We propose a gradient-based inverse-designed, static phase-mask doublet to generate arbitrary 2D intensity wavefronts using a one-dimensional (1D) intensity spatial light modulator (SLM). We numerically simulate the capability of mapping each point in a 49 element 1D array to a distinct $7\times <\#comment/>7$2D spatial distribution. Our proposed method will significantly relax the routing complexity of electrical control signals, possibly enabling high-speed, sub-wavelength 2D SLMs leveraging new materials and pixel architectures. 

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3. Plasmonic metagrating-interlayer semiconductor (PMIS) structure for enhancing photodetection via hot-electron injection

   https://doi.org/10.1364/OE.527826  

   Vu, Nga; Heidarzadeh, Parham; Chen, Pai-Yen (September 2024, Optics Express)

   Internal photoemission or hot-electron injection (HEJ) occurring at the metal-semiconductor (MS) Schottky interface has shown great promise in sub-bandgap photodetection and photovoltaics. In this paper, we put forward a plasmonic metagrating-interlayer-semiconductor (PMIS) structure that can significantly enhance the photon-to-electron conversion efficiency of HEJ-based optoelectronic devices. Thanks to the effect of image force-induced barrier lowering, a metal-interlayer-semiconductor (MIS) heterojunction with an ultrathin 2D material interlayer can considerably facilitate the hot electron transport across the Schottky barrier, resulting in a high internal quantum efficiency (IQE). Meanwhile, nanopatterning the MIS heterojunction into the plasmonic metagrating enables high optical absorption such that the device’s external quantum efficiency (EQE) can be nearly equal to its IQE. In addition, this device can be wavelength- and polarization-selective by tailoring the geometry and dimensions of plasmonic metagrating, thereby paving a promising path toward bandgap-independent photodetection, energy harvesting, and photocatalysis. 

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4. Strain-engineered high-responsivity MoTe2 photodetector for silicon photonic integrated circuits

   https://doi.org/10.1038/s41566-020-0647-4  

   Maiti, R.; Patil, C.; Saadi, M. A.; Xie, T.; Azadani, J. G.; Uluutku, B.; Amin, R.; Briggs, A. F.; Miscuglio, M.; Van Thourhout, D.; et al (June 2020, Nature Photonics)

   In integrated photonics, specific wavelengths such as 1,550 nm are preferred due to low-loss transmission and the availability of optical gain in this spectral region. For chip-based photodetectors, two-dimensional materials bear scientifically and technologically relevant properties such as electrostatic tunability and strong light–matter interactions. However, no efficient photodetector in the telecommunication C-band has been realized with two-dimensional transition metal dichalcogenide materials due to their large optical bandgaps. Here we demonstrate a MoTe2-based photodetector featuring a strong photoresponse (responsivity 0.5 A W–1) operating at 1,550 nm in silicon photonics enabled by strain engineering the two-dimensional material. Non-planarized waveguide structures show a bandgap modulation of 0.2 eV, resulting in a large photoresponse in an otherwise photoinactive medium when unstrained. Unlike graphene-based photodetectors that rely on a gapless band structure, this photodetector shows an approximately 100-fold reduction in dark current, enabling an efficient noise-equivalent power of 90 pW Hz–0.5. Such a strain-engineered integrated photodetector provides new opportunities for integrated optoelectronic systems. 

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5. Highly Textured Sn‐Doped Ga ₂ O ₃ Epilayers for Economically Viable Solar‐Blind Ultraviolet Photodetectors with High Responsivity

   https://doi.org/10.1002/adom.202500325  

   Episcopo, Nathan; Das, Debabrata; Bowers, Cynthia; Mahalingam, Krishnamurthy; Stevenson, Peter R; Ramana, C V (July 2025, Advanced Optical Materials)

   Abstract The design and development of solar‐blind photodetectors utilizing ultrawide bandgap semiconductors have garnered significant attention due to their extensive utility in specialty commercial sectors. Solar‐blind photodetectors that display excellent photosensitivity, fast response time and are produced using cost‐effective fabrication steps will fulfill the performance demands in relevant applications. Herein, highly textured Sn‐doped Ga₂O₃thin film metal‐semiconductor‐metal type deep‐UV photodetectors using a commercially scalable magnetron sputtering method are reported. Commercially achievable growth and fabrication steps are intentionally chosen to demonstrate an economically viable photodetection workflow without compromising the device's performance. In‐depth structural, morphological, chemical, and optical characterization are reported to optimize the configuration for further device fabrication and testing. Under transient triggering circumstances, a fast response time of ≈500 ms is reported, accompanied by a responsivity of ≈60.5 A W⁻¹. The detectivity, external quantum efficiency, and photo‐to‐dark current ratio values are reported as 1.6 × 10¹³Jones, 2.8 × 10⁴%, and 17.4, respectively. The overall device performance and cost‐effective fabrication process for solar‐blind UV photodetection using Sn‐doped Ga₂O₃is promising. The approach holds promise for significant implications toward the development of electronics capable of functioning in extreme environments and exhibits substantial potential for enhancing low‐cost UV photodetector technology. 

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