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An ultrafast all-optical shutter is presented, based on a simple two-color two-photon absorption technique. For time-resolved luminescence measurements this shutter is an interesting alternative to the optical Kerr gate. The rejection…
The epitaxial growth of two-dimensional (2D) $\beta-In_2Se_3$ material was obtained over 2-inches c-sapphire wafers using molecular beam epitaxy (MBE). Excellent quality of thick (90 nm) and very thin films, down to two quintuple layers (2…
We study two-photon scattering of a tightly focused weak light beam from a small atomic ensemble of two-level atoms (2LAs). This is similar to the scattering of photons from an atomic ensemble in a one-dimensional waveguide. The scaling of…
We solve the nonlinear Maxwell equations in an InP-based dielectric metamaterial, considering both two-photon absorption and photo-induced free-carrier absorption. We obtain the intensity-dependent reflection, absorption, and effective…
Near perfect infrared light absorption at multi-spectral wavelengths has been experimentally demonstrated by using multiplexed metal square plasmon resonance structures. Optical power absorption over 95% has been observed in dual-band…
Two-photon excited fluorescence (TPEF) is a standard technique in modern microscopy but still affected by photo-damage of the probe. It was proposed that TPEF can be enhanced by using entangled photons, but has proven to be challenging.…
We show that the photoluminescence emitted from a dense, two-component ensemble of quantum dots is significantly higher than that from quantum dots of either of the two pure systems (CdS and ZnO). The semiconductor nanocomposite, in which…
In this article, we report the first observation of nanosecond laser induced transient dual absorption bands, one in the bandgap (TA1) and another in the sub-bandgap (TA2) regions of a-Ge5As30Se65 thin films. Strikingly, these bands are…
[Background] The electromagnetic form factors of the proton measured by unpolarized and polarized electron scattering experiments show a significant disagreement that grows with the squared four momentum transfer ($Q^{2}$). Calculations…
Optical absorption is one of fundamental light-matter interactions. In most materials, optical absorption is a weak perturbation to the light. In this regime, absorption and emission are irreversible, incoherent processes due to strong…
Absorption imaging with quasi-resonant laser light is a commonly used technique to probe ultra-cold atomic gases in various geometries. Here we investigate some non-trivial aspects of this method when it is applied to in situ diagnosis of a…
Nonlinear interferometry with entangled photons allows for characterizing a sample without detecting the photons interacting with it. This method enables highly sensitive optical sensing in the wavelength regions where efficient detectors…
All optical detectors to date annihilate photons upon detection, thus excluding repeated measurements. Here, we demonstrate a robust photon detection scheme which does not rely on absorption. Instead, an incoming photon is reflected off an…
Two-level systems (TLS) of unclear physical origin are a major contributor to decoherence in superconducting qubits. The interactions of individual TLS with a qubit can be detected via various spectroscopic methods, most of which have…
We present an asymmetric bifacial graphene metasurface to realize tunable and broadband coherent perfect absorption (CPA) at terahertz (THz) frequencies. The proposed design is composed of two dissimilar graphene square patch metasurfaces…
Recent investigations suggest that the use of non-classical states of light, such as entangled photon pairs, may open new and exciting avenues in experimental two-photon absorption spectroscopy. Despite several experimental studies of…
We report on Doppler-free laser spectroscopy in a Cs vapor cell using a dual-frequency laser system tuned on the Cs D$_1$ line. Using counter-propagating beams with crossed linear polarizations, an original sign-reversal of the usual…
We have used a photothermal technique, in which chopped light heats the front surface of a small ( ~ 1 mm2) sample and the chopping frequency dependence of thermal radiation from the back surface is measured with a liquid nitrogen cooled…
Optical two-dimensional coherent spectroscopy (2DCS) is a powerful ultrafast spectroscopic technique that can greatly benefit from the unique features of a femtosecond laser operating at a kHz repetition rate. However, isolating specific…
This paper presents a motion-free technique for characterizing the focal length of any spherical convex or concave lens. The measurement system uses a Gaussian Beam from a Laser Source (LS), an Electronically Controlled Variable Focus Lens…