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Low-loss depressed cladding waveguide architecture is highly attractive for improving the laser performance of waveguide lasers. Selleck PCI-34051 We report on the design and fabrication of the "ear-like" waveguide structures formed by a set of parallel tracks in neodymium-doped yttrium aluminum garnet (NdYAG) crystal via femtosecond laser writing. The obtained "ear-like" waveguides are with more symmetric mode profiles and lower losses by systematically comparing the guiding properties of two kinds of normal cladding waveguide. Efficient waveguide lasers are realized based on the designed structure in both continuous wave and pulsed regimes. Combined the high-gain from cladding waveguide and special "ear-like" structure, a passively fundamentally Q-switched laser with the narrow pulse width and the high repetition rate has been obtained by using tin diselenide (SnSe2) as saturable absorber.We report a flashlamp pumped mechanically Q-switched (MQS) 2.94 μm ErYAG laser based on a spinning mirror with a highest output energy of 805 mJ at a pulse duration of 61 ns and 13 MW of peak power at 1 Hz repetition rate. This record output energy was achieved with the use of 300 mm long MQS ErYAG laser cavity consisting of a 70% output coupler, 7 × 120 mm AR coated Er(50%)YAG crystal, and 4200 rad/s angular speed of the spinning mirror. The pulse jitter was also measured by using optical triggering and was smaller than 10 ns for 150 ns Q-switched pulses, which could be applicable to many laser applications where precise synchronization of pulses is required.X-ray beams reflected from a single layer or multilayer coating are widely used for X-ray tomography, holography, and X-ray phase contrast imaging. However, the observed irregular stripe patterns from either unfocused or defocused beams often cause disturbing artifacts and seriously deteriorate the image quality. In this work, we investigate the origin of these irregular fine structures using the wave optics theory. The connection to similar results obtained by the geometric optics theory is also presented. The proposed relation between the second derivative of the wavefront and the irregular structures was then verified by conducting at-wavelength metrology with the speckle-based wavefront sensing technique. This work will not only help to understand the formation of these irregular structures but also provide the basis for manufacturing future 'stripe-free' refection optics.We developed a method to model fluorescence, absorption, and scattering in nanophotonic systems using ergodic Markov chains. Past works have used absorbing Markov chains to find the long-run angle-dependent distribution of emitted photons. In contrast, we use ergodic Markov chains to focus on the steady state distribution of photons within various media, giving additional insight into the macroscopic optical response during illumination. We show that the method reproduces Beer-Lambert's Law and Kirchhoff's Law, and can quantify deviations from these laws when their assumptions are violated. We also use the method to model luminescent solar concentrators (LSCs) based on semiconductor nanocrystals.We present the first frequency-quadrupled linearly-polarized Q-switched neodymium-doped fiber laser generating > 500 mW average power at 226 nm. For this purpose, an amplified Q-switched oscillator using novel large-mode-area (LMA) fibers and generating up to 24 W average power (15 kW peak power) at 905 nm was developed. Two nonlinear frequency conversion stages using a LBO crystal for SHG and a BBO crystal for FHG generate respectively up to 4.9 W average power in the deep blue at 452 nm and a maximum of 510 mW average power in the deep ultra-violet (DUV) at 226 nm. Performance limitations and further improvements are discussed.Fourier ptychography tomography (FPT) is a novel computational technique for coherent imaging in which the sample is numerically reconstructed from images acquired under various illumination directions. FPT is able to provide three-dimensional (3D) reconstructions of the complex sample permittivity with an increased resolution compared to standard microscopy. In this work, FPT is applied to coherent anti-Stokes Raman scattering (CARS) imaging. We show on synthetic data that complex third-order susceptibilities can be reconstructed in 3D from a limited number of widefield CARS images. In addition, we observe that the non-linear interaction increases significantly the potential of CARS-FPT compared to linear FPT in terms of resolution. In particular, with a careful choice of the pump and Stokes beam directions, CARS-FPT is able to provide optical sectioning even in transmission configuration.The traditional frequency selective surface (FSS) needs further improvement with the development of stealth technology, and the design of multifunctional FSSs is essential. In this letter, an active absorptive FSS (AFSS) has been designed based on the absorption structure of the spoof surface plasmon polariton (SSPP) and the switching activity of the active FSS. The active FSS embedded with PIN diodes realizes the shift of two transmission/reflection frequency bands by controlling the bias voltage of the feed network, which switches from one band-pass response (at around 3.06 GHz) to the other (at around 4.34 GHz). And when one of the transmission windows switches to the other, the original transmission window closes. The upper plasmonic structure achieves a continuous and efficient absorption band from 6.31 to 8.34 GHz. A sample was also fabricated and carried out to verify the numerical simulation, and the experimental and simulation results are consistent. This work provides new ideas for the design of active AFSS and promotes its application in common aperture radome, antenna isolation, and electromagnetic shielding.Optical parametric chirped-pulse amplification (OPCPA) is a light amplification technique that provides the combination of broad spectral gain bandwidth and large energy, directly supporting few-cycle pulses with multi-terawatt (TW) peak powers. Saturation in an OPCPA increases the stability and conversion efficiency of the system. However, distinct spectral components experience different gain and do not saturate under the same conditions, which reduces performance. Here, we describe a simple and robust approach to control the saturation for all spectral components. The demonstrated optimal saturation increases the overall gain, conversion efficiency and spectral bandwidth. We experimentally obtain an improvement of the pulse energy by more than 18%. This technique is easily implemented in any existing OPCPA system with a pulse shaper to maximize its output.Coherent two-dimensional (2D) electronic spectroscopy has become a standard tool in ultrafast science. Thus it is relevant to consider the accuracy of data considering both experimental imperfections and theoretical assumptions about idealized conditions. It is already known that chirped excitation pulses can affect 2D line shapes. In the present work, we demonstrate performance-efficient, automated characterization of the full electric field of each individual multipulse sequence employed during a 2D scanning procedure. Using Fourier-transform spectral interferometry, we analyze how the temporal intensity and phase profile varies from scanning step to scanning step and extract relevant pulse-sequence parameters. This takes into account both random and systematic variations during the scan that may be caused, for example, by femtosecond pulse-shaping artifacts. Using the characterized fields, we simulate and compare 2D spectra obtained with idealized and real shapes obtained from an LCD-based pulse shaper. Exemplarily, we consider fluorescence of a molecular dimer and multiphoton photoemission of a plasmonic nanoslit. The deviations from pulse-shaper artifacts in our specific case do not distort strongly the population-based multidimensional data. The characterization procedure is applicable to other pulses-shaping technologies or excitation geometries, including also pump-probe geometry with multipulse excitation and coherent detection, and allows for accurate consideration of realistic optical excitation fields at all inter-pulse time-delays.THz conductivity of large area MoS2 and MoSe2 monolayers as well as their vertical heterostructure, MoSe2MoS2 is measured in the 0.3-5 THz frequency range. Compared to the monolayers, the ultrafast THz reflectivity of the MoSe2MoS2 heterobilayer is enhanced many folds when optically excited above the direct band gap energies of the constituting monolayers. The free carriers generated in the heterobilayer evolve with the characteristic times found in each of the two monolayers. Surprisingly, the same enhancement is recorded in the ultrafst THz reflectivity of the heterobilayer when excited below the MoS2 bandgap energy. A mechanism accounting for these observations is proposed.We introduce a scalable photonic platform that enables efficient generation of entangled photon pairs from a semiconductor quantum dot. Our system, which is based on a self-aligned quantum dot- micro-cavity structure, erases the need for complex steps of lithography and nanofabrication. We experimentally show collection efficiency of 0.17 combined with a Purcell enhancement of up to 1.7. We harness the potential of our device to generate photon pairs entangled in time bin, reaching a fidelity of 0.84(5) with the maximally entangled state. The achieved pair collection efficiency is 4 times larger than the state-of-the art for this application. The device, which theoretically supports pair extraction efficiencies of nearly 0.5 is a promising candidate for the implementation of bright sources of time-bin, polarization- and hyper entangled photon pairs in a straightforward manner.In this paper, we present a method to distinguish neoplastic tissues from non-neoplastic ones using calibration-free laser-induced breakdown spectroscopy (CF-LIBS). For this propose, plasma emission was collected from neoplastic and non-neoplastic tissues taken from the ovarian cancer mice models. Results were obtained by utilizing the characteristic plasma emission lines of different elements that have been confirmed in the investigated samples. From the temporal evolution of plasma emission, the optimum temporal-observation-windows are identified for LIBS investigation. The concentrations of the detected elements in tissues were measured by a calibration-free approach based on data process of plasma parameters at the local thermodynamic equilibrium. The neoplastic specimens provided more energetic plasma than non-neoplastic ones that resulting in higher peaks intensities, electron density and electron temperature especially in the early windows (between 0.1 µs to 0.8 µs). Results demonstrated higher concentrations of major and trace elements such as Mg, Fe, Ca, Na, and K in the neoplastic tissues. Finally, the results using CF-LIBS method were found to be in good agreement with that of Inductive coupled plasma-optical emission spectroscopy (ICP-OES).A highly sensitive fiberized hydrogen sensor based upon Mach-Zehnder interference (MZI) is experimentally demonstrated. The hydrogen sensor consists of an MZI realized by creating an air cavity inside the core of a half-pitch graded-index fiber (GIF) by use of femtosecond laser micromachining. Thermosensitive polymer was filled into the air cavity and cured by UV illumination. Subsequently, the external surface of the polymer-filled MZI was coated with Pt-loaded tungsten trioxide (WO3). The exothermic reaction occurs as Pt-loaded WO3 contacts the target of the sensing, i.e. hydrogen in the atmosphere, which leads to a significant local temperature rise on the external surface of the coated MZI sensor. The sensor exhibits a maximum sensitivity up to -1948.68 nm/% (vol %), when the hydrogen concentration increases from 0% to 0.8% at room temperature. Moreover, the sensor exhibits a rapid rising response time (hydrogen concentration increasing) of ∼38 s and falling response time (hydrogen concentration decreasing) of ∼15 s, respectively.
Homepage: https://www.selleckchem.com/products/pci-34051.html
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