The paper reports the efficient UV and terahertz generation from a 1.29 mm thick and Type I, =28.9 cut (bismuth triborate, BIBO) crystal using femtosecond and nanoseconds laser pulses. We have employed 800 nm wavelength pulses of 50 and 140 fs obtained from a Ti:sapphire laser amplifier and oscillators at 1 kHz and 80 MHz repetition rates, respectively. The conversion efficiency of second-harmonic generation (SHG) was ∼50 while that obtained for terahertz (THz) generations was of the order of 1.85×10. In addition, LDS-698 dye laser radiation tunable between 650-700 nm was also used as a source for SHG between the 325-350 nm range. The dye laser was pumped by SHG (532 nm) radiation from an electro-optically -switched Nd:YAG laser having a pulse repetition rate of 10 Hz and a pulse width of 10 ns. A conversion efficiency of 4.01% was obtained for generation of UV at 343.5 nm. Finally, we have measured the transmission, refractive index, absorbance, and conductivity properties of BIBO crystal in the THz domain. We also ascertained the coherence length, relative permittivity and reflectivity of the crystal.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/AO.424241 | DOI Listing |
Adv Mater
January 2025
State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, China.
Terahertz (THz) signals are crucial for ultrawideband communication and high-resolution radar, demanding miniaturized detectors that can simultaneously measure multiple parameters such as intensity, frequency, polarization, and phase. Traditional detectors fail to meet these needs. To address this, we introduce a plasmon polariton atomic cavity (PPAC) detector based on monolayer graphene, offering a multifunctional, monolithic, and miniaturized solution.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Electrical and Computer Engineering, Tarbiat Modares University, Tehran, 14115-194, Iran.
With the increasing global attention to deep learning and the advancements made in applying convolutional neural networks in electromagnetics, we have recently witnessed the utilization of deep learning-based networks for predicting the spectrum and electromagnetic properties of structures instead of traditional tools like fully numerical-based methods. In this study, a Convolutional Neural Network (CNN is proposed for predicting spoof surface plasmon polaritons, enabling the examination of the absorption spectrum of metallic multilevel-grating structures (MMGS) and designing various sensor devices and absorbers in the shortest time possible. To expedite the training process of this network, a semi-analytical method of rigorous coupled-wave analysis (RCWA) enhanced with the fast Fourier factorization (FFF) technique has been employed, significantly reducing the data generation time for training.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
January 2025
Department of Cardiovascular Surgery, The General Hospital of Western Theater Command, College of Medicine, Southwest Jiaotong University, Chengdu 610031, Sichuan, China. Electronic address:
Exosomal microRNAs (miRNAs) are among the most common biomarkers for tumor diagnosis. However, single-miRNA detection lacks ideal sensitivity and specificity for diagnosing a certain tumor in clinics. In this work, we fabricated a convenient multi-miRNA detection platform for sensitive and specific detection on exosomal miRNAs in the plasma of patients using a terahertz (THz) metamaterial biosensor on the basis of strand displacement amplification (SDA) and AuNPs.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
ECE Department, University of Wisconsin at Madison, 1415 Engineering Dr, Rm 3442, Madison, WI 53706, USA, Madison, Wisconsin, 53706, UNITED STATES.
Two-dimensional (2D) van der Waals materials are shaping the landscape of next-generation devices, offering significant technological value thanks to their unique, tunable, and layer-dependent electronic and optoelectronic properties. Time-domain spectroscopic techniques at terahertz (THz) frequencies offer noninvasive, contact-free methods for characterizing the dynamics of carriers in 2D materials. They also pave the path toward the applications of 2D materials in detection, imaging, manufacturing, and communication within the increasingly important THz frequency range.
View Article and Find Full Text PDFLow-temperature phase (β-form) barium borate (BBO) is one of the most important nonlinear crystals that has been widely used for optical second-harmonic generation (SHG), especially with femtosecond sources. There was growing interest in its applications in the direct generation of terahertz (THz) radiations, but it was hindered by the lack of knowledge of its basic properties in the THz range. In a recent study based on first-principles quantum chemistry calculation, we found that the theoretically calculated refractive indices of β-BBO in the THz frequency range do not agree with the previously reported values.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!