High power supercontinuum generation by dual-color femtosecond laser pulses in fused silica

High power supercontinuum (SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the case of single laser pulse, and the spectral energy density between the two fundamental laser wavelengths is getting significantly higher by optimizing the phase matching angle of the BBO. It exceeds μJ/nm over 490 nm range which is from 380 nm to 870 nm, overcoming the disadvantage of relative lower power in the ranges far from fundamental wavelength.

the Synthesis of Cinnamon Nanoparticles by Using Laser Ablation Technique

The natural polyphenolic compound that cinnamon contains is well known for its various biological activities, a broad variety of pharmacological and therapeutic properties. Diversified biomedical and pharmacological applications benefit from organic nanoparticles with controlled properties. Bioactive and non-toxic, cinnamon nanoparticles (CNPs) can be effective antibacterial agents. Driven by this idea, we prepared spherical CNPs using liquid (PLAL) pulse laser ablation technique and defined those NPs. Using Q-switched Nd : YAG With a wavelength of 1064 nm pulse laser of constant energy 500 mj , And different laser pulses ( 250 , 500 , 750 , 1000 ) pulse /sec a pure cinnamon target submerged in liquid ethanol (5 mL) was ablated. The results on the composition, morphology and optical properties of as-grown CNPs of differing laser fluence were determined. Samples were described through Fe-SEM , UV-Vis , FTIR , The synergy between ethanol as liquid growth media and fundamental laser wavelength has been due to certain distinctive characteristics of CNPs. It has been developed that the spherical CNPs achieved in the suspension of ethanol could be beneficial for antioxidant purposes.

Laser and Light-Based Device Education in a Plastic Surgery Residency Program: A Continuing Medical Education Overview

The increasing prevalence of laser use, particularly in plastic surgery, demands the need for education of both practitioners and trainees to ensure patient safety and efficacy. The purpose of this continuing medical education module is to provide the learner with a detailed outline for laser training education for plastic surgery trainees. In this overview, a discussion of the characteristics of light, an introduction to fundamental laser principles, a comparison between lasers and pulsed light systems, and examples of several therapeutic applications for light-based devices in the clinical setting will be presented. Additionally, the five parameters necessary for operation of light-based devices, as well as the importance of laser safety education will be reviewed. It is the authors’ hope that this CME will provide both practicing plastic surgeons and trainees the proper education on the lasers and pulsed light devices that they will use in their clinical practices.

Picosecond Lifetime Hot Electrons in TiO2 Nanoparticles for High Catalytic Activity

A large number of studies have examined the origins of high-catalytic activities of nanoparticles, but very few have discussed the lifetime of high-energy electrons in nanoparticles. The lifetime is one of the factors determining electron transfer and thus catalytic activity. Much of the lifetime of electrons reported in the literature is too short for a high transfer-efficiency of photo-excited electrons from a catalyst to the attached molecules. We observed TiO2 nanoparticles using the femtosecond laser two-color pump-probe technique with photoemission electron microscopy having a 40 nm spatial resolution. A lifetime longer than 4 ps was observed together with a fast decay component of 100 fs time constant when excited by a 760 nm laser. The slow decay component was observed only when the electrons in an intermediate state pumped by the fundamental laser pulse were excited by the second harmonic pulse. The electronic structure for the asymmetry of the pump-probe signal and the origin of the two decay components are discussed based on the color center model of the oxygen vacancy.

Cocrystals of 2-Aminopyrimidine with Boric Acid—Crystal Engineering of a Novel Nonlinear Optically (NLO) Active Crystal

Crystal engineering of novel materials for nonlinear optics (NLO) based on 2-aminopyrimidine yielded two molecular cocrystals with boric acid—trigonal (P3221 space group) 2-aminopyrimidine—boric acid (3/2) and monoclinic (C2/c space group) 2-aminopyrimidine—boric acid (1/2). In addition to crystal structure determination by single crystal X-ray diffraction, the cocrystals were characterized by powder X-ray diffraction and vibrational spectroscopy (FTIR and FT Raman). Large single crystals of the non-centrosymmetric cocrystal 2-aminopyrimidine—boric acid (3/2) were grown to study the optical properties and determine the second harmonic generation (SHG) efficiency (using 800 nm fundamental laser line) of powder samples.

Electron Scattering Processes in Non-Monochromatic and Relativistically Intense Laser Fields

The theoretical analysis of four fundamental laser-assisted non-linear scattering processes are summarized in this review. Our attention is focused on Thomson, Compton, Møller and Mott scattering in the presence of intense electromagnetic radiation. Depending on the phenomena under considerations, we model the laser field as a single laser pulse of ultrashort duration (for Thomson and Compton scattering) or non-monochromatic trains of pulses (for Møller and Mott scattering).

Fluctuations, Dissipation, and Noise

General concepts in the theory of fluctuations and dissipation are reviewed and applied to examples in quantum optics. Brownian motion, Fokker-Planck and Langevin equations, and the Wiener-Khintchine theorem are reviewed, followed by a derivation and discussion of the fluctuation-dissipation theorem. The general problem of an oscillator coupled to a heat bath is revisited, as is the nonrelativistic theory of radiation reaction. The general ideas about fluctuations and dissipation developed in the first part of the chapter are then applied to the theory of the fundamental laser linewidth, the photon statistics of linear amplifiers and attenuators, the noise figure, amplified spontaneous emission, and the quantum theory of the beam slitter and homodyne detection.