98%
921
2 minutes
20
This study investigates the transmission mechanism of the beat-frequency signal of the fundamental wave during extra-cavity second harmonic generation (SHG) in Nd:YAG laser. By precisely controlling intracavity anisotropic losses, we observe that the beat-frequency signal in the second harmonic had approximately twice the amplitude of the fundamental wave. Furthermore, the output efficiency of the second harmonic is significantly improved. A theoretical model for the transmission of the fundamental wave's beat-frequency signal in the extra-cavity SHG is developed. For the first time, this study reveals the relationship between the beat frequency of the fundamental wave and second harmonic in extra-cavity SHG, both theoretical and experimental. These findings offer valuable insights for designing high-efficiency extra-cavity SHG systems for isotropic lasers.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/OE.553951 | DOI Listing |
J Acoust Soc Am
September 2025
Department of Head and Neck Surgery, University of California, Los Angeles, 31-24 Rehab Center, 1000 Veteran Avenue, Los Angeles, California 90095-1794, USA.
The goal of this study was to understand the interaction between the voice source spectral shape, formant tuning, and fundamental frequency in determining the vocal tract contribution to vocal intensity. Computational voice simulations were performed with parametric variations in both vocal fold and vocal tract configurations. The vocal tract contribution to vocal intensity was quantified as the difference in the A-weighted sound pressure level between the radiated sound pressure and the sound pressure at the glottis.
View Article and Find Full Text PDFChem Sci
September 2025
State Key Laboratory of Crystal Materials, Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, Tianjin University of Technology Tianjin 300384 China
Nonlinear optical (NLO) crystals capable of expanding the spectral region of solid-state are of great importance for many high-tech applications, yet their rational structure design remains a great challenge because of the conflicting property requirements among second harmonic generation (SHG) response, ultraviolet (UV) cut-off edge, and birefringence. Herein, based on the chemical disubstitution of the classic NLO crystal SrBeBO (SBBO), , substituting [BO] triangles with larger π-conjugated [BO] groups and substituting high-toxic [BeO] tetrahedra with environment-friendly [AlO] tetrahedra, a new high-performance aluminoborate NLO crystal, BaAlBO, has been successfully designed and synthesized. The theoretical calculations and optical property measurements indicate that BaAlBO exhibits not only the largest SHG response among the reported aluminoborates (2.
View Article and Find Full Text PDFAdv Mater
September 2025
Research Center for Crystal Materials, CAS Key Laboratory of Functional Materials and Devices for Special Environmental Conditions, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, 830011, P. R. China.
The generation of coherent deep-ultraviolet (DUV) radiation via nonlinear frequency conversion remains a major scientific and technological challenge in modern optics. To date, only a very limited number of nonlinear optical (NLO) crystals-such as KBBF, ABF, and quartz-have been experimentally demonstrated to support measurable direct second-harmonic generation (SHG) at wavelengths of 177 nm or shorter. There is a pressing need to develop alternative materials or strategies that enable efficient frequency conversion in the DUV region.
View Article and Find Full Text PDFJ Voice
September 2025
Department of Speech and Language Therapy, Faculty of Health Sciences, Hacettepe University, Ankara, Turkey. Electronic address:
Objectives: In individuals over 65, age is an essential factor in voice changes. Acoustic and aerodynamic norms guide clinicians in interpreting clinical voice assessment results. This study aimed to present aerodynamic-acoustic voice measurements in older individuals with no voice complaints.
View Article and Find Full Text PDFCarbohydr Polym
November 2025
Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium. Electronic address:
Cellulose nanocrystals (CNCs) have emerged as promising candidates for chiroptical functional materials due to their ability to form cholesteric liquid crystals with tunable periodicity. The quality of the final cholesteric phase is influenced by the nucleation, growth and coalescence mechanism of the initial droplets, known as tactoids. Current research focuses on understanding the size and morphological transformations of these tactoids, to gain deeper insights into their dynamic behavior and, in turn, to better control the final properties of novel photonic materials.
View Article and Find Full Text PDF