A5014532691- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Plasmonic and Surface Plasmon Research
- Atmospheric Ozone and Climate
- Metamaterials and Metasurfaces Applications
- Semiconductor Lasers and Optical Devices
- Terahertz technology and applications
- Laser Design and Applications
- Advanced Fiber Laser Technologies
- Strong Light-Matter Interactions
- Spectroscopy and Quantum Chemical Studies
- Thermal Radiation and Cooling Technologies
- Molecular spectroscopy and chirality
- Mechanical and Optical Resonators
- Photonic Crystals and Applications
- Sparse and Compressive Sensing Techniques
- Orbital Angular Momentum in Optics
- Analytical Chemistry and Sensors
- Semiconductor Quantum Structures and Devices
- Blind Source Separation Techniques
- Atmospheric chemistry and aerosols
- Advanced Antenna and Metasurface Technologies
- Photorefractive and Nonlinear Optics
- Atmospheric and Environmental Gas Dynamics
- Complex Network Analysis Techniques
Technical University of Munich
2020-2025
Schott (Germany)
2020-2025
City University of New York
2023
The Graduate Center, CUNY
2023
CUNY Advanced Science Research Center
2023
The University of Texas at Austin
2013-2022
University of California, San Diego
2020-2021
The Ohio State University
2008-2018
MIREA - Russian Technological University
2018
Bellingham Technical College
2015
Consistency is a key property of all statistical procedures analyzing randomly sampled data. Surprisingly, despite decades work, little known about consistency most clustering algorithms. In this paper we investigate the popular family spectral algorithms, which clusters data with help eigenvectors graph Laplacian matrices. We develop new methods to establish that, for increasing sample size, those converge certain limit operators. As result, can prove that one two major classes (normalized...
We apply the Pancharatnam-Berry phase approach to plasmonic metasurfaces loaded by highly nonlinear multiquantum-well substrates, establishing a platform control wave front at will based on giant localized effects. this design flat for efficient second-harmonic radiation, including beam steering, focusing, and polarization manipulation. Our findings open new direction optics, in which matching issues are relaxed, an unprecedented level of local is achieved over thin devices with responses.
The "double descent" risk curve was proposed to qualitatively describe the out-of-sample prediction accuracy of variably-parameterized machine learning models. This article provides a precise mathematical analysis for shape this in two simple data models with least squares/least norm predictor. Specifically, it is shown that peaks when number features $p$ close sample size $n$, but also decreases towards its minimum as increases beyond $n$. behavior contrasted "prescient" select an priori...
Abstract Optical activity and circular dichroism are fascinating physical phenomena originating from the interaction of light with chiral molecules or other nano objects lacking mirror symmetries in three-dimensional (3D) space. While optical properties weak most naturally occurring materials, they can be engineered significantly enhanced synthetic media known as metamaterials, where spatial symmetry their building blocks is broken on a nanoscale. Although originally discovered 3D...
We report on our progress in the development of a terahertz quantum cascade laser source based intracavity difference-frequency mixing dual-wavelength mid-infrared with active region engineered to possess giant second-order nonlinear susceptibility. In this letter, we demonstrate devices that operate at λ1=8.9μm and λ2=10.5μm produce output λ≈60μm via generation 7μW power 80K, 1μW 250K, still approximately 300nW 300K.
We report terahertz quantum cascade lasers operating in pulsed mode at an emission frequency of 3 THz and up to a maximum temperature 178 K. The improvement the is achieved by using three-quantum-well active region design with resonant-phonon depopulation utilizing copper, instead gold, for cladding material metal-metal waveguides.
Optical activity in sum-frequency vibrational spectra has been observed for the first time chiral liquids. The electric-dipole allowed element of nonlinear susceptibility appears to be 3 orders magnitude smaller than typical achiral elements. This is partly because chirality requires a breakdown Born-Oppenheimer approximation.
We demonstrate a compact, single-mode quantum cascade laser source continuously tunable between 8.7 and 9.4μm. The consists of an array distributed feedback lasers with closely spaced emission wavelengths fabricated monolithically on single chip driven by microelectronic controller. Our is suitable for variety chemical sensing applications. Here, we use it to perform absorption spectroscopy fluids.
In recent years a considerable amount of work in graphics and geometric optimization used tools based on the Laplace-Beltrami operator surface. The applications Laplacian include mesh editing, surface smoothing, shape interpolations among others. However, it has been shown [13, 24, 26] that popular cotangent approximation schemes do not provide convergent point-wise (or even L2) estimates, while many rely estimation. Existence such an open question [13].
A large number of learning algorithms, for example, spectral clustering, kernel Principal Components Analysis and many manifold methods are based on estimating eigenvalues eigenfunctions operators defined by a similarity function or kernel, given empirical data. Thus the analysis it is an important problem to be able assess quality such approximations. The contribution our paper two-fold: 1. We use technique concentration inequality Hilbert spaces provide new much simplified proofs results...
We report the unequivocal demonstration of mid-infrared mode-locked pulses from a semiconductor laser. The train short was generated by actively modulating current and hence optical gain in small section an edge-emitting quantum cascade laser (QCL). Pulses with pulse duration at full-width-at-half-maximum about 3 ps energy 0.5 pJ were characterized using second-order interferometric autocorrelation technique based on nonlinear well infrared photodetector. mode-locking dynamics QCLs modelled...
In the last decade quantum cascade lasers (QCLs) have become most widely used source of mid-infrared radiation, finding large scale applications because their wide tunability and overall high performance. However far-infrared (terahertz) QCLs lagged behind in terms performance impact due to inability so far achieving room temperature operation. Here we review recent research that has led a new class QCL light sources overcome these limitations leading operation terahertz spectral range, with...
We present an algorithm for approximating the Laplace-Beltrami operator from arbitrary point cloud obtained a k-dimensional manifold embedded in d-dimensional space. show that this PCD Laplace (Point-Cloud Data Laplace) converges to on underlying as becomes denser. Unlike previous work, we do not assume data samples are independent identically distributed probability distribution and require global mesh. The resulting is easy implement. experimental results indicating even sets sampled...
Gradient metasurfaces have recently been demonstrated to provide control of the phase scattered fields over subwavelength scales, enabling a broad range linear optical components in flat, ultrathin, integrable platform. Additionally, development nonlinearmetasurfaces has disrupted conventional nonlinear device design by relaxing matching constraints, reducing size and dimensionality, providing record values localized responses. However, extending “flat optics” paradigm case faces important...
Electrically tunable mid‐infrared metasurfaces with nanosecond response time and broad tuning range are reported. Electrical is achieved by employing strong polaritonic coupling of electromagnetic modes in metallic nanoresonators voltage‐tunable inter‐subband transitions semiconductor heterostructures, tailored for a giant quantum‐confined Stark effect. Experimentally, 220‐nm‐thick multi‐quantum‐well layer sandwiched between ground plane metal patterned plasmonic nanoresonators....
Ultrathin metasurfaces with record-high nonlinear optical response of 1.2 × 106 pm V−1 for second harmonic generation are experimentally demonstrated in the mid-infrared spectral range. A power conversion efficiency 0.075% is achieved a 400-nm-thick (λ/25) metasurface at pump intensity only 15 kW cm−2. As service to our authors and readers, this journal provides supporting information supplied by authors. Such materials peer reviewed may be re-organized online delivery, but not copy-edited...
In the past decade mathematical theory of machine learning has lagged far behind triumphs deep neural networks on practical challenges. However, gap between and practice is gradually starting to close. this paper I will attempt assemble some pieces remarkable still incomplete mosaic emerging from efforts understand foundations learning. The two key themes be interpolation its sibling over-parametrization. Interpolation corresponds fitting data, even noisy exactly. Over-parametrization...
Strong interaction of graphene with light accounts for one its most remarkable properties: the ability to absorb 2.3% incident light's energy within a single atomic layer. Free carrier injection via field-effect gating can dramatically vary optical properties graphene, thereby enabling fast graphene-based modulators intensity. However, very thinness makes it difficult modulate other fundamental property wave: phase. Here we demonstrate that considerable phase control be achieved by...
Abstract Terahertz quantum cascade laser (QCL) sources based on intra-cavity difference frequency generation are currently the only electrically pumped monolithic semiconductor light operating at room temperature in 1–6-THz spectral range. Relying active regions with giant second-order nonlinear susceptibility and Cherenkov phase-matching scheme, these devices demonstrated drastic improvements performance past several years can now produce narrow-linewidth single-mode terahertz emission that...