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1. Optoelectronic control of surface plasmon polaritons at metal-doped semiconductor interfaces

   https://doi.org/10.1088/2515-7647/adcfe1  

   Vinnakota, Raj K; Schliemann, Mayra M; Shahriar, Shaimum (May 2025, Journal of Physics: Photonics)

   Abstract We present a metal–semiconductor (M–S) based electro-optic modulator designed for functional plasmonic circuits, utilizing the active control of surface plasmon polaritons (SPPs) at M–S junction interfaces. Through self-consistent multiphysics simulations, including electromagnetic, thermal, and current–voltage (IV) characteristics, we estimate bias- and doping concentration-dependent SPP modulation and switching times. This study focuses on germanium-based Schottky contacts and can be extended to other semiconducting materials. We performed parametric analysis using the developed thermo-electro-optic model to identify device parameters and dimensions for enhanced optical confinement and faster operation. The studied device exhibits signal modulation exceeding −28 dB, responsivity greater than −1800 dB V⁻¹, and switching rates of 8 GHz, suggesting potential data rates above 16 Gbit s⁻¹. Additionally, frequency response analysis using the numerical model confirms the device’s electrical tunability and predicts a 3 dB bandwidth of up to 4 GHz. These findings highlight the significant potential of Schottky junctions as active components in the development of plasmonic-based integrated circuits. 

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2. High Efficiency Antenna Integrated Electro-Optic modulator for Sensing Applications

   A. Akhiyat and J.L. Volakis (April 2021, 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, Singapore)

   Abstract—The efficiency of Electro-Optic Modulators (EOM) is directly related to how the rf signal is imposed onto the optical signal. Other factors affecting this efficiency are: the selected architecture and the Electro-Optic materials responsible for modulation through the Electro-Optic Effect. In this paper we demonstrate a millimeter wave antenna integrated EOM that operates at 94 GHz. To improve efficiency, the antenna is integrated directly onto the active region of the electro-optic effect based EOM. Notably, conventional antennas had to be modified to achieve a feed port that is best suited for the selected EOM architecture. For the antenna design optimization, we devised a design procedure that is more suitable for these type of devices. We proposed a design methodology that insures an optimum Field Enhancement (FE) that is responsible for modulation. A novel overall EOM architecture that promotes increased efficiency that makes use of the inherently lossy EO material only where needed in the optical link by making use of an adiabatic transition from a passive Optical waveguide to active portion of the optical link. 

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3. Phase‐Shifted Bragg Gratings from High Refractive Index Chalcogenide Hybrid Inorganic/Polymers: Fabrication and Thermo‐Optic Characterization

   https://doi.org/10.1002/adom.202401296  

   Nishant, Abhinav; Kim, Kyung‐Jo; Himmelhuber, Roland; Lee, Taeheon; Kleine, Tristan S; Pyun, Jeffrey; Norwood, Robert A (June 2024, Advanced Optical Materials)

   Abstract In this study, the first fabrication of phase‐shifted Bragg gratings utilizing chalcogenide hybrid inorganic/organic polymers (CHIPs) is presented based on poly(sulfur‐random‐(1,3‐isopropenylbenzene) to measure the thermo‐optic coefficient (TOC) of this new class of optical polymers. The unique properties ofCHIPs, such as high index contrast and low optical losses, are leveraged to fabricate Bragg gratings that enable precise determination of the TOC and glass transition temperature (T_g) of these polymers. The optical measurement introduces a novel technique to measure the TOC and T_gof optical polymers which can be difficult to determine using traditional methods such as differential scanning calorimetry (DSC) after fabrication into photonic device constructs. The findings demonstrate thatCHIPs exhibit low thermo‐optic (TO) effects, making them exceptionally well‐suited for the development of thermally stable photonic integrated circuits. 

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4. Space Qualifying Silicon Photonic Modulators and Circuits

   https://doi.org/10.1364/OFC.2024.Th3D.4  

   Mao, Dun; Chang, Lorry; Dong, Po; Gu, Tingyi (January 2024, Optica Publishing Group)

   Here we performed the first space experiments of photonic integrated circuits, revealing the critical roles of energetic charged particles. The year-long cosmic radiation does not change carrier mobility but reduces free carrier lifetime, resulting in unchanged electro-optic modulation efficiency and well-expanded optoelectronic bandwidth. 

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5. Microheater hotspot engineering for repeatable multi-level switching in foundry-processed phase change silicon photonics

   https://doi.org/10.21203/rs.3.rs-4631376/v1  

   Sun, Hongyi; Lian, Chuanyu; Vásquez-Aza, Francis; Kari, Sadra Rahimi; Huang, Yi-Siou; Restelli, Alessandro; Vitale, Steven A; Takeuchi, Ichiro; Hu, Juejun; Youngblood, Nathan; et al (July 2024, Research Square - Nature Portfolio)

   Abstract Nonvolatile photonic integrated circuits employing phase change materials have relied either on optical switching mechanisms with precise multi-level control but poor scalability or electrical switching with seamless integration and scalability but mostly limited to a binary response. Recent works have demonstrated electrical multi-level switching; however, they relied on the stochastic nucleation process to achieve partial crystallization with low demonstrated repeatability and cyclability. Here, we re-engineer waveguide-integrated microheaters to achieve precise spatial control of the temperature profile (i.e., hotspot) and, thus, switch deterministic areas of an embedded phase change material cell. We experimentally demonstrate this concept using a variety of foundry-processed doped-silicon microheaters on a silicon-on-insulator platform to trigger multi-step amorphization and reversible switching of Sb₂Se₃and Ge₂Sb₂Se₄Te alloys. We further characterize the response of our microheaters using Transient Thermoreflectance Imaging. Our approach combines the deterministic control resulting from a spatially resolved glassy-crystalline distribution with the scalability of electro-thermal switching devices, thus paving the way to reliable multi-level switching towards robust reprogrammable phase-change photonic devices for analog processing and computing. 

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