A5001983361- Semiconductor Quantum Structures and Devices
- 2D Materials and Applications
- Optical Network Technologies
- Advanced Fiber Laser Technologies
- Semiconductor Lasers and Optical Devices
- Photonic and Optical Devices
- Perovskite Materials and Applications
- MXene and MAX Phase Materials
- Laser-Matter Interactions and Applications
- Chalcogenide Semiconductor Thin Films
- Quantum Information and Cryptography
- Quantum optics and atomic interactions
- Graphene research and applications
- Electronic and Structural Properties of Oxides
- Organic and Molecular Conductors Research
- Plasmonic and Surface Plasmon Research
- Nonlinear Optical Materials Studies
- Metamaterials and Metasurfaces Applications
- Quantum Dots Synthesis And Properties
- Advanced Photonic Communication Systems
- Nanocluster Synthesis and Applications
- Spectroscopy and Quantum Chemical Studies
- Advanced Materials Characterization Techniques
- Nanoplatforms for cancer theranostics
- Machine Learning in Materials Science
Stanford University
2017-2023
SLAC National Accelerator Laboratory
2022-2023
Stanford Medicine
2023
Menlo School
2023
Technion – Israel Institute of Technology
2007-2016
We report light emission around 1 eV (1240 nm) from heterostructures of MoS_{2} and WSe_{2} transition metal dichalcogenide monolayers. identify its origin in an interlayer exciton (ILX) by wide spectral tunability under out-of-plane electric field. From the static dipole moment state, temperature twist-angle dependence, comparison with electronic structure calculations, we assign this ILX to fundamental between K valleys system. Our findings gain access physics intrinsically incommensurate...
Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. Because such excitons display weak overlap, most studies have examined only the lowest-energy through photoluminescence. We directly measured dielectric response of interlayer which we accessed using their static electric dipole moment. thereby determined an intrinsic radiative lifetime 0.40 nanoseconds for lowest direct-gap exciton in a...
Layered semiconducting transition metal dichalcogenides (TMDs) are promising materials for high-specific-power photovoltaics due to their excellent optoelectronic properties. However, in practice, contacts TMDs have poor charge carrier selectivity, while imperfect surfaces cause recombination, leading a low open-circuit voltage (VOC) and therefore limited power conversion efficiency (PCE) TMD photovoltaics. Here, we simultaneously address these fundamental issues with simple MoOx (x ≈ 3)...
We report direct observations of Rabi oscillations and self-induced transparency in a quantum dot optical amplifier operating at room temperature. The experiments make use pulses whose durations are shorter than the coherence time which characterized using Cross-Frequency-Resolved Optical Gating. A numerical model solves Maxwell Schrödinger equations accounts for inhomogeneously broadened nature gain medium confirms experimental results. is also used to explain relationship between...
Excitons in two-dimensional transition metal dichalcogenides have a valley degree of freedom that can be optically manipulated for quantum information processing. Here, we integrate MoS2 monolayers with achiral silicon disk array metasurfaces to enhance and control valley-specific absorption emission. Through the coupling metasurface electric magnetic Mie modes, intensity lifetime emission neutral excitons, trions, defect bound excitons enhanced shortened, respectively, while spectral shape...
We describe a finite-difference time-domain (FDTD) model of long (edge-emitting) gain medium based on quantum-dot (QD) in-a-well structure under the framework Maxwell-Schrödinger equations. The includes dynamic behavior QD including an excited state incorporated within carrier rate equations and considers density dependence refractive index. enables us also to calculate diffusion effects, which, unlike in quantum well structures, play important role devices, since capture escape processes...
This work shows a direct method for the observation of light-matter interactions in semiconductor optical amplifier. Of high significance is that experiments are carried out at room temperature presence many body scatting processes which was thought to induce very rapid decoherence.
The optical and structural properties of a new kind InAs/InGaAlAs/InP quantum dot (QD)-like objects grown by molecular beam epitaxy have been investigated. These nanostructures were found to significantly more symmetrical shapes compared the commonly obtained dash-like geometries typical this material system. enhanced symmetry has achieved due use an As2 source consequent shorter migration length indium atoms. Structural studies based on combination scanning transmission electron microscopy...
van der Waals (vdW) heterostructures provide a powerful method to control the alignment of energy bands atomically thin 2D materials. Under light illumination, optical responses are dominated by Coulomb-bound electron–hole quasiparticles, for example, excitons, trions, and biexcitons, whose contributions accordingly depend on types heterostructures. For type-II heterostructures, it has been well established that excitation results in electrons holes separated different layers, radiative...
There is interest in what happens to ultrashort light pulses propagating through a quantum-dot semiconductor optical amplifier waveguide. In this experiment, the influence of nonresonant propagation effects, such as linear dispersion, two-phonon absorption, and Kerr-like, on intensity frequency profile shown be strong enough that they must included any modeling.
We report on a characterization of fundamental gain dynamics in recently developed InAs/InP quantum-dot semiconductor optical amplifiers. Multi-wavelength pump-probe measurements were used to determine recovery rates, following powerful pump pulse, at various wavelengths for different bias levels and excitation powers. The was dominated by coupling between the electronic states quantum-dots high energy carrier reservoir via capture escape mechanisms. These processes also wavelength...
We present a numerical study of coherent control in room temperature InAs/InP quantum dot (QD) semiconductor optical amplifier (SOA) using shaped ultra-short pulses. Both the gain and absorption regimes were analyzed for pulses with central wavelengths lying on either side inhomogeneously broadened spectrum. The experiments predict that regime interactions between QD SOA pulse can be controlled by incorporating quadratic spectral phase (QSP) profile. sequential interaction medium different...
The charge carrier dynamics of improved InP-based InAs/AlGaInAs quantum dot (QD) semiconductor optical amplifiers are examined employing the multi-wavelength ultrafast pump-probe measurement technique. transient transmission response continuous wave probe shows interesting dynamical processes during initial 2-3 ps after pump pulse, when carriers originating from two photon absorption contribute least to recovery. effects excitations and electrical bias levels on recovery gain in...
We show that the long sought utilization of quantum mechanical phenomena for practical purposes is feasible by demonstrating ability to control coherent Rabi oscillations in a room-temperature dot semiconductor optical amplifier (SOA) with shaped light pulses. The experiments, confirmed comprehensive numerical calculation, reveal linearly chirped ultrashort pulses, interacting coherently upon propagation short wavelength slope SOA gain spectrum, may enhance or suppress (depending on chirp)...
We describe direct measurements at a high temporal resolution of the changes experienced by phase and amplitude an ultra-short pulse upon propagation through inhomogenously broadened semiconductor nanostructured optical gain medium. Using cross frequency-resolved gating technique, we analyze 150 fs-wide pulses propagating along InP based quantum dash amplifier in both quasi-linear saturated regimes. For very large electrical excitations, second, trailing peak is generated enhanced unique...
We demonstrate a novel laser oscillation scheme in an InAs / InP wire-like quantum dash gain medium.A short optical pulse excites carriers by two photon absorption which relax to the energy levels providing thereby enabling oscillations.The nonlinear dynamic interaction is analyzed and quantified using multi-color pump-probe measurements shows highly efficient excitation process larger more than order of magnitude compared common well bulk media.The response nonlinearly induced line...
We investigate the nonlinear propagation of an ultra-short, 150 fs, optical pulse along waveguide a quantum dot (QD) laser operating above threshold. demonstrate that among various processes experienced by propagating pulse, four-wave mixing (FWM) between and two oscillating counter-propagating cw fields is dominant one. FWM has important consequences. One creation spectral hole located in vicinity frequency. The width determined effective carrier gain relaxation time. second modification...
The ability to induce, observe and control quantum coherent interactions in room temperature, electrically driven optoelectronic devices is of outmost significance for advancing science engineering towards practical applications. We demonstrate here a interference phenomena, Ramsey fringes, an inhomogeneously broadened InAs/InP dot (QD) ensemble the form 1.5 mm long optical amplifier operating at temperature. Observation fringes semiconductor QD was previously achieved only cryogenic...
Storage and manipulation of quantum information requires (nearly) perfect timing---or precisely timed pulse sequences, anyhow. In memory based on photon echoes, for example, the appearance time echo must be determined with great accuracy. This study shows how to control echoes in a quantum-dot optical amplifier operating at room temperature. As is distributed device, propagation effects are dominant generation pulse, shaping excitation serves echo's strength.
Light matter coherent interactions require that the state induced in be maintained for duration of observation. The only way to induce and observe such room temperature semiconductors, where coherence time is order a few hundred femtoseconds, use ultrashort pulse excitations an ultrafast characterization technique. For media comprising ensemble nanostructure semiconductors as self-assembled quantum dots, gain broadening inhomogeneity also affects interaction. Moreover, when form active...
We present a monolithic photo-receiver based upon the InP/GalnAs HBT technology for optical communication at 1.55 μm. The photoreceiver consists of top-illuminated photodiode and transimpedance traveling wave amplifier. same layers are used diodes base collector junction transistors. An advanced amplifier design, that achieves high bandwidth-to- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f<sub>T</sub></i> ratio, expands frequency response...