arXiv subjects

Jianda Shao

Publications and source records attributed to Jianda Shao.

6 recordsLinked to original sources

arXiv2026

Annealing-Induced Structural and Optical Evolution of Ion-Beam-Sputtered Ta2O5 Films for High-Power Laser Applications

Tantalum pentoxide (Ta2O5) thin films deposited by ion beam sputtering (IBS) are essential components in high-power laser systems, where post-deposition annealing is routinely used to optimize film quality. In this work, we systematically investigate the structural and optical evolution of IBS-deposited Ta2O5 single layers subjected to post-deposition annealing at temperatures from 400 to 800 $^{\circ}\mathrm{C}$. The films undergo an amorphous-to-polycrystalline transition between 600 $^{\circ}\mathrm{C}$ and 700 $^{\circ}\mathrm{C}$, accompanied by a marked increase in surface roughness. Argon bubbles inherently incorporated during IBS serve as structural markers: their size correlates positively with the surface roughness from the as-deposited to 700 $^{\circ}\mathrm{C}$ but decouples at 800 $^{\circ}\mathrm{C}$, revealing a transition from matrix-relaxation-dominated to surface-diffusion-dominated behavior. Transmittance spectra show a red shift at 400 and 600 $^{\circ}\mathrm{C}$ which can be explained by physical thickness increase. Weak absorption decreases from ~6 ppm in as-deposited films to ~2 ppm at 400-600 $^{\circ}\mathrm{C}$ due to annihilation of oxygen vacancies, rises markedly at 700 $^{\circ}\mathrm{C}$ due to grain-boundary defects and then drops again at 800 $^{\circ}\mathrm{C}$ as grain boundaries relax. We identify 400 $^{\circ}\mathrm{C}$ as the optimal annealing window for IBS-deposited Ta2O5 single layers, with the lowest surface roughness and effectively reducing weak absorption while preserving the amorphous phase.

cond-mat.mtrl-sci↗

arXiv2026

Pathway to lowest-energy structures and stress relaxation for the surface triple junction of copper

The behavior of surface triple junctions (STJ) at emergent grain boundaries on free surfaces is critical to the microstructure evolution, and therefore to the stability of next generation interconnects. Yet, despite this significant importance, its lowest-energy structure and local stress have remained persistently unknown. Here, we fill this critical gap through high-resolution experimental mapping of the local surface deformation at STJs of a symmetrical tilt grain boundaries with [111] rotation axis and misorientation angles 13.17°, the analysis of the local core-shifted structure and stress relaxation, and ergodic searching metastable structures accordingly with the molecular-statics (MS) calculation. The computation clearly shows the zipped Y-shaped notch as the lowest-energy structures for this group of STJs, the line profile of which is consistent with the experimental observation. This energetic preference was well explained by the stress delocalization mechanism and was tested for a wide range of boundaries with even deeper core-shift depth using machine learning methods based on the data obtained from MS calculation. By revealing the elusive thermodynamics of STJs, our findings advance the research field by redefining the energetic framework for capillary driven structure evolution and providing foundation for understanding kinetically diffusive deformation and for engineering thin-film interconnects and related materials.

cond-mat.mtrl-sci↗

arXiv2018

Motionless and fast measurement technique for obtaining the spectral diffraction efficiencies of a grating

The measurement of the spectral diffraction efficiencies of a diffraction grating is essential for improving the manufacturing technique and for assessing the grating's function in practical applications. The drawback of the currently popular measurement technique is its slow speed due to the hundreds of repetitions of two kinds of time-consuming mechanical movements during the measuring process (i.e., the rotation of the mechanical arm to capture the light beam, and the mechanical variation of the output wavelength of the grating monochromator). This limitation greatly restricts the usage of this technique in dynamic measurement. In this manuscript, we present a motionless and fast measurement technique for obtaining the spectral diffraction efficiencies of a plane grating, effectively eliminating the aforementioned two kinds of mechanical movement. Herein, the proposed solution for removing the first kind of mechanical movement is tested, and the experimental result shows that the proposed method can be successfully used to measure the plane transmission grating's spectral diffraction efficiencies in the wavelength range of 550-750 nm. The method for eliminating the second kind of mechanical movement is not verified in this manuscript; however, we think that it is very straightforward and commercially available. We estimate that the spectral measurement can be achieved on a millisecond timescale by combining the two solutions. Our motionless and fast measuring technique will find broad applications in dynamic measurement environments and mass industrial testing.

physics.ins-det↗

arXiv2018

Apparatus for measuring the uniformity of the optical transmittance of a semispherical surface at normal incidence

In this paper, we build an apparatus for measuring the optical transmittance and its uniformity for a semispherical surface at normal incidence; the system is primarily comprised of a traditional double-beam photometric framework and a novel custom-made mechanical structure with multidimensional degrees of freedom. During the measurement process, a key aligning step is adopted to guarantee that the center point of the semispherical surface stands still in the light beam while scanning the hemispherical optical element point by point around the horizontal and vertical axes, which ensures that the laser beam is always normally incident onto the surface of the hemisphere. The experimental results show that the uniformity of the optical transmittance for a semispherical optical glass can be successfully characterized by the system, with a three-cycle repeatability error of 0.026% being demonstrated. Our system solves the problem of traditional spectrophotometers when measuring the spectral property of a hemispherical surface and thus can be popularized in similar applications.

physics.optics↗

arXiv2017

Setup for measuring the optical propagation time in matter

Optical propagation time in matter could reveal fruitful information, such as the velocity of light and the sample's refractive index. In this paper, we build a simple and robust setup for measuring the optical propagation time in matter for a known distance, the system uses high frequency square signal as the signal carrier, and a lock-in amplifier is employed to obtain the phase difference between the reference square signal and the other one penetrating the sample, in this way the optical time of flight in matter can be obtained by a background subtraction process. Primary experimental result confirms the feasibility of the newly proposed measuring theory, which can be used to measure easily in high-speed the speed of light and the refractive index of optical transparent material, compared with the currently popular measuring technique using oscilloscope, potential advantage of our proposed method employing lock-in amplifier is that high accuracy are promising, and in contrast with the presently most popular method for measuring the sample's refractive index based on the minimum deviation angle, superiority of our suggested method is the easy preparation of the sample, the convenient operability and the fast measuring speed.

physics.ins-det↗

arXiv2016

Surface modeling for optical fabrication with linear ion source

We present a concept of surface decomposition extended from double Fourier series to nonnegative sinusoidal wave surfaces, on the basis of which linear ion sources apply to the ultra-precision fabrication of complex surfaces and diffractive optics. It is the first time that we have a surface descriptor for building a relationship between the fabrication process of optical surfaces and the surface characterization based on PSD analysis, which akin to Zernike polynomials used for mapping the relationship between surface errors and Seidel aberrations. Also, we demonstrate that the one-dimensional scanning of linear ion source is applicable to the removal of surface errors caused by small-tool polishing in raster scan mode as well as the fabrication of beam sampling grating of high diffractive uniformity without a post-processing procedure. The simulation results show that, in theory, optical fabrication with linear ion source is feasible and even of higher output efficiency compared with the conventional approach.

physics.acc-ph↗