Publications by authors named "Yongji Yu"

This paper addresses the thermal instability of lasers resulting from the thermal effects of the 2 µm gain medium, proposing what we believe to be a novel compensation scheme that integrates machine learning technology with multi-segment bonded Tm: YAG crystals and negative lenses, based on the thermal focal length model of a thick thermal lens. This approach significantly optimizes thermal compensation and facilitates rapid assessment of the light-emitting behavior trends of Tm: YAG lasers. Firstly, the thermal behavior of conventional and multi-segment bonded Tm: YAG crystals is analyzed.

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As an emerging two-dimensional (2D) Group-VA material, bismuth selenide (BiSe) exhibits favorable electrical and optical properties. Here, three distinct morphologies of BiSe were obtained from bulk BiSe through electrochemical intercalation exfoliation. And the morphologies of these nanostructures can be tuned by adjusting solvent polarity during exfoliation.

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The precise energy and temporal control advantages of the 2 µm double-pulse laser have diverse applications in laser processing, biomedicine, and communications. The Ho: YAP Q-switched double pulse laser, a complex system, demands comprehensive theoretical analysis and precise experimental operations, especially when managing pulse overlap and ensuring output stability. Traditional design methods, time-consuming and labor-intensive, pose challenges in error elimination and susceptibility to environmental and device instabilities.

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This paper reports a 3.8 µm pulse burst self-optical parametric oscillator (SOPO) employing the Nd:MgO:PPLN crystal, achieving programmable mid-infrared pulse burst output based on step-active Q-switching technology. Building on the intracavity optical parametric oscillator (IOPO) theory, a theoretical model for the step-active Q-switched self-optical parametric oscillator is developed by introducing idler photon and step loss terms.

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We present a 3.8 µm self-optical parametric oscillator (SOPO) pumped by a pulsed laser diode (LD) based on only one Nd:MgO:PPLN crystal. The problem of heat accumulation in Nd:MgO:PPLN crystals caused by high-power laser pumping is significantly optimized.

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This paper introduces a structured beam with Archimedes spiral intensity distribution. The Archimedes spiral (AS) beam is the composite of a helical-axicon generated (HAG) Bessel beam and a Gaussian (GS) beam. We observed the spiral intensity patterns using computational holography, achieving the tuning over spiral arms number and spiral spacing.

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As abruptly autofocusing beams, autofocusing Bessel beams (ABBs) have been proven to be a class solution for the Helmholtz equation [Opt. Express31, 33228 (2023)10.1364/OE.

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We introduce what we believe to be a new family of abruptly autofocusing waves named autofocusing Bessel beams (ABBs). Since the beams only strongly influence the area near the focus, it holds promise for medical laser treatment and optical tweezers. By the angular spectrum method, ABBs are proved to be a class solution for the Helmholtz equation.

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The 2 μm wavelength belongs to the eye-safe band and has a wide range of applications in the fields of lidar, biomedicine, and materials processing. With the rapid development of military, wind power, sensing, and other industries, new requirements for 2 μm solid-state laser light sources have emerged, especially in the field of lidar. This paper focuses on the research progress of 2 μm solid-state lasers for lidar over the past decade.

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Type 2 diabetes mellitus (T2DM) is a multifactorial disorder that leads to alterations in gene regulation. ncRNAs have the characteristics of tissue specificity, disease specificity, timing specificity, high stability and post transcriptional regulation effect. These preconditions are more conducive to promote ncRNA to become a new biomarker for clinical diagnosis.

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We explored has_circ_0071106 as a diagnostic marker for type 2 diabetes (T2DM) in south China, and predicted the functional mechanism of the target circRNA. A total of 107 T2DM patients and 107 healthy reference persons were included as the research objects. In the first stage, the circRNA microarray was used to detect the peripheral blood of 4 T2DM and 4 control groups to screen the differential expression profile of circRNA.

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