A5009362630- Photonic and Optical Devices
- Plasmonic and Surface Plasmon Research
- Advanced Fiber Laser Technologies
- Photonic Crystals and Applications
- Metamaterials and Metasurfaces Applications
- Mechanical and Optical Resonators
- Semiconductor Lasers and Optical Devices
- Optical Network Technologies
- Semiconductor Quantum Structures and Devices
- Advanced Antenna and Metasurface Technologies
- Strong Light-Matter Interactions
- Terahertz technology and applications
- Advanced Fiber Optic Sensors
- Neural Networks and Reservoir Computing
- Gold and Silver Nanoparticles Synthesis and Applications
- Analytical Chemistry and Sensors
- Millimeter-Wave Propagation and Modeling
- Nanowire Synthesis and Applications
RWTH Aachen University
2023-2024
Technische Universität Berlin
2021-2023
Aristotle University of Thessaloniki
2016-2022
Electro-optic modulators are an indispensable part of photonic communication systems, largely dictating the achievable transmission rate. Recent advances in materials and fabrication/processing techniques have brought new elements a renewed dynamic to research on optical modulation. Motivated by opportunities, this Perspective reviews state art integrated electro-optic modulators, covering broad range contemporary platforms. To provide better overview status current assessment different...
We propose metal-semiconductor-metal cavity arrays as active elements of electrically tunable metasurfaces operating in the terahertz spectrum. Their function is based on reverse biasing Schottky junction formed between top metal strips and n-type semiconductor buried beneath. A gate bias a back reflector controls electron depletion layer thickness thus tuning Drude permittivity array. Using rigorous multiphysics framework which combines Maxwell equations for waves drift-diffusion model...
Electro-optic waveguide modulators exploiting the carrier-induced epsilon-near-zero effect in transparent conducting oxides are comprehensively studied and evaluated using a rigorous multi-physics modeling framework. The examined amplitude integrate indium tin oxide with two representative examples of silicon-on-insulator technology, silicon-rib silicon-slot platform, latter design exhibiting superior performance, featuring μm modulation lengths, switching speeds exceeding 100 GHz, sub-pJ...
The correct numerical calculation of the resonance characteristics and, principally, quality factor Q contemporary photonic and plasmonic resonant systems is utmost importance, since defines bandwidth affects nonlinear spontaneous emission processes. Here, we comparatively assess commonly used methods for calculating using spectral simulations with commercially available, general-purpose software. We study applicability range these through judiciously selected examples covering different...
Two-dimensional (2D) or sheet materials have been recently recognized as fascinating for nonlinear photonics. Here, we develop a rigorous mathematical framework based on perturbation theory and temporal coupled-mode capable of analyzing third-order, ${\ensuremath{\chi}}^{(3)}$, multichannel processes in resonant systems comprising 2D materials. The is applied to model degenerate four-wave mixing guided-wave graphene plasmon-polariton structure, consisting standing-wave resonator directly...
Higher-order digital modulation formats are demonstrated by electrically inducing free-carrier concentration changes in thin films of transparent conducting oxides, integrated into well-established silicon-photonic waveguiding architectures. The proposed near-infrared modulators employ as physical platforms the silicon-rib and silicon-slot waveguides, exploiting highly dispersive carrier-dependent epsilon-near-zero behavior oxides to modulate optical carrier. Advancing existing studies on...
Metallic nanocavity lasers provide important technological advancement towards even smaller integrable light sources. They give access to widely unexplored lasing physics in which the distinction between different operational regimes, like those of thermal or a coherent emission, becomes increasingly challenging upon approaching device with near-perfect spontaneous-emission coupling factor $\beta$. In fact, quantum-optical studies have be employed reveal transition emission intensity...
Transparent conducting oxides and graphene have dominated research on optical modulation in recent years. Regrettably, studies are often unrealistic, which hinders a clear understanding of the state art. The authors revisit both material technologies to present an equitable, quantitative comparison common grounds, rigorously modeling their shared physical principles. Both inline resonant configurations examined from ground up, using silicon photonic platform as underlying structure. proposed...
We report on the extraction of silver losses in range 10 K-180 K by performing temperature-dependent micro-photoluminescence measurements conjunction with numerical simulations silver-coated nanolasers around near-infrared telecommunication wavelengths. By mapping changes quality factor into silver-loss variations, imaginary part permittivity is extracted at cryogenic temperatures. The latter estimated to reach values an order magnitude lower than room-temperature values....
We present optical devices that employ free-carrier effects for routing and modulation applications. By electrically controlling the carrier concentration in indium tin oxide, we realize an electro-optic modulator employing silicon slot waveguide platform. Moreover, using undoped silicon, demonstrate clock utilizing self-pulsation a long-range hybrid plasmonic disk resonator design can additionally function as voltage-controlled frequency modulator. Lastly, by tuning graphene conductivity,...
Electro-optic phase modulation schemes are investigated by inducing carrier-concentration changes in transparent conducting oxide semiconductors, integrated well-established silicon-photonic platforms. By exploiting the epsilon-near-zero effect, binary phase-shift keying is manifested, resulting high-speed solutions of reduced footprint, compared to conventional all-silicon designs.
This work presents the design of electrically tunable solid-state metamaterial absorbers in terahertz spectrum. The proposed devices consist a metal-insulator-metal resonant cavity formed between subwavelength metal stripe grating and back reflector. dielectric spacing metallic parts is occupied by deeply layer n-doped GaAs. By reverse biasing Schottky junction at interface GaAs top grating, thickness associated carrier depletion zone controlled and, hence, complex permittivity profile...
A Lorentzian-to-Gaussian lineshape transition is investigated in an InP-based silver-coated nanolaser with verified lasing operation. The effect stems from cavity eigenmodes extending into free space and serves as a convenient indicator for high- β nanolasers.
We develop a perturbation theory framework for modeling nonlinear resonators comprising dispersive sheet materials. It is applied to model optical bistability with graphene-based resonant structures in the THz and near-infrared regimes.
Silicon-photonic modulators are investigated, integrating either graphene or epsilon-near-zero films, tuned by the field effect. Both waveguide and resonance modulation schemes demonstrated, allowing for compact, efficient, broadband designs.
We discuss arrays of metal-semiconductor-metal cavities as electrically tunable terahertz metasurfaces. The operation the considered device is based on reverse biasing Schottky junction formed between top metal strips and n-type semiconductor buried beneath. effective Drude permittivity cavity array tuned by changing depletion layer thickness via a gate bias applied back reflector. Combining Maxwell equations for waves with drift-diffusion model carriers into multiphysics framework, we show...
A rigorous mathematical framework combining temporal coupled-mode theory (CMT) and perturbation for modeling wave mixing in resonant systems involving 2D (sheet) materials is developed, expanding the existing literature that focuses on bulk systems. Throughout this work, conductive are naturally modeled with a nonlinear surface current term, rigorously implemented CMT formalism to accurately describe system response using coefficients calculated after linear finite-element (FEM) simulations....
Graphene exhibits high third-order nonlinearity in both THz and NIR regimes. Here, we consider single- multi-channel nonlinear phenomena resonators comprising graphene to exploit its nonlinearity. Specifically, study optical bistability the with a graphene-covered silicon slot microring resonator degenerate four-wave mixing regime ribbon resonator. For calculating response, employ recently developed perturbation theory/coupled mode theory framework which is efficient accurate. We find low...
We describe investigations on quantum fluctuations in semiconductor lasers relating to a lineshape anomaly while lasing at the spontaneous-emission limit. Measurements show an emerging Gaussian component, contradicting cavity-QED predicted Lorentzian lineshape. Theoretical studies indicate intrinsic contribution from intricate cavity-outcoupling and active-medium nonlinearity interplay.
In this work we present a microscopic theory based on cavity QED semiconductor model to investigate the emission of InGaAsP-based metallic nanolasers. The consistent approach modelling interplay quantum optical and effects allows for excellent agreement with pump-power dependant experimental results.
We verify the transition from thermal to coherent emission in excitation-dependent optical measurements on InGaAsP-based multiple quantum well (MQW) metallic nanolasers under continuous-wave excitation thresholdless regime and observe distinctive lasing features for resonance modes through temperature-dependent series with excellent theoretical agreement.