We report on what is to our knowledge the first realization of a quasi-phase-matched optical parametric oscillator (OPO) based on a crystal with a cylindrical shape. The main reason for interest in this device is its broad, continuous tuning. In experiments with a 1064-nm pump, the signal tuning range was equal to 525 nm (1515-2040 nm), and the corresponding idler was continuously tuned over 1340 nm (2220-3560 nm). The angular tuning was 26 degrees , with only a minor variation of the OPO threshold over the entire tuning range.
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http://dx.doi.org/10.1364/ol.26.001882 | DOI Listing |
Nature
January 2025
Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
The integrated frequency comb generator based on Kerr parametric oscillation has led to chip-scale, gigahertz-spaced combs with new applications spanning hyperscale telecommunications, low-noise microwave synthesis, light detection and ranging, and astrophysical spectrometer calibration. Recent progress in lithium niobate (LiNbO) photonic integrated circuits (PICs) has resulted in chip-scale, electro-optic (EO) frequency combs, offering precise comb-line positioning and simple operation without relying on the formation of dissipative Kerr solitons. However, current integrated EO combs face limited spectral coverage due to the large microwave power required to drive the non-resonant capacitive electrodes and the strong intrinsic birefringence of LiNbO.
View Article and Find Full Text PDFSci Rep
January 2025
Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510631, People's Republic of China.
Prominent platforms based on thin-film lithium niobate (TFLN) are superior integrated-photonics platforms for efficient optical parametric amplification (OPA), however, previously few studies have been systematically reported the gain-boosting performance of TFLN waveguides compared to bulk LN waveguides. Here, we optimize two TFLN waveguides with dispersion engineering for high-efficiency and ultra-broadband gain of OPA, then report comparative results about the efficient ultra-broadband OPA of TFLN waveguides in the case of low loss, optimized waveguide length and pump power. Note that the efficient ultra-broadband OPA of TFLN waveguides is represented by the peak gain (71.
View Article and Find Full Text PDFFront Bioeng Biotechnol
January 2025
Department of Orthopaedics, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical Universit, Guangzhou, China.
Objective: The aim of this study is to assess the kinematic changes in the knee joint during walking in patients with isolated PCL-deficiency (PCLD) to determine the presence of walking-related joint instability (mechanical instability-abnormal displacement form structural damage). Additionally, the study seeks to provide biomechanical insights into the observed differences between subjective and objective assessments.
Methods: 35 healthy volunteers and 27 patients with isolated PCLD (both involved and uninvolved sides) were included in the study.
Lasers Med Sci
January 2025
Escola Superior de Soluções Estrategicas ESE, São Paulo, Brazil.
The Endolift® technique, introduced in 2005, gained popularity among medical and non-medical professionals as a non-surgical approach using subdermal laser devices. However, its widespread adoption lacked a thorough understanding of its physiological interaction, resulting in controversies over its effectiveness and safety. This study aimed to assess the evidence of Endolift® efficacy, parametrization, and safety by analyzing adverse events.
View Article and Find Full Text PDFBMC Pediatr
January 2025
Department of Anatomy, Histology and Anthropology, Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Ciurlionio Str. 21, Vilnius, 03101, Lithuania.
Background: Prematurity is linked to diverse and significant health outcomes, but a comprehensive understanding of its long-term multisystem impacts remains limited.
Methods: Retrospective longitudinal cohort study on 417 preterm children born between 2000 and 2015 explores the incidence, dynamics, and interrelationships of health conditions from infancy to adolescence. Data on 1818 diagnoses, categorised by birth weight (BW) and gestational age (GA) and documented according to ICD-10, were analysed using non-parametric tests and negative binomial regression models.
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