http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lingyu Wang,Yu Miao,Mingzhu Xu,Xiumin Gao 한국광학회 2023 Current Optics and Photonics Vol.7 No.2
Radially polarized beams with the ability to generate a sub-wavelength sized spot in a longitudinal field provides significant applications in microscopic imaging, optical tweezers, lithography and so on. However, this excellent property can also be achieved based on conventional circularly polarized beams. Here, we demonstrate its ability to create a strong longitudinal field by comparing the tight focusing characteristics of fractional-order vortex modulated radial polarized and left-handed circular polarized Bessel-Gauss beams. Additionally, the possibility of generating arbitrary fractional-order vortex modulated Bessel-Gauss beams with a strong longitudinal field is demonstrated. A special modulation method of left-handed circularly polarized Bessel-Gauss beams modulated by a fractional-order vortex is adopted creatively and a series of regulation laws are obtained. Specifically, the fractional-order phase modulation parameter n can accurately control the number of optical lobes. The ratio of the pupil radius to the incident beam waist β 1 can control the radius of the optical lobes. The first-order Bessel function amplitude modulation parameter β 2 can control the number of layers of optical lobes. This work not only adds a new modulation method for optical micromanipulation and optical communication, but also enriches the research on fractional vortex beams which has very important academic significance.
한영덕 한국물리학회 2020 새물리 Vol.70 No.2
In non-relativistic electron vortex beams, the spin of an electron is treated as a degree of freedom independent from the momentum of the electron. However, for a relativistic electron described by the Dirac equation, its spin is intimately related to its momentum, as is manifested by spinorbit coupling, helicity conservation, etc. In this paper, we construct a Bessel beam solution by superposing momentum eigen functions, whose spins are parallel to the momentum or at a constant angle with the beam axis. By introducing a Gaussian envelope function for the normalization of the wave functions, we calculate the expectation values for physical quantities such as the spin and magnetic moment. Also, the differences from the results of previous studies are discussed. 비상대론적 전자 소용돌이 빔에서 전자의 스핀은 운동량과 독립적인 자유도로 취급된다. 그러나 Dirac 방정식으로 기술되는 상대론적 전자의 경우 스핀-궤도 상호작용, 나선도 보존 등에서 보는 바와 같이스핀은 운동량과 밀접한 관계가 있다. 따라서 상대론적 소용돌이 빔을 기술하는 파동함수에는 이러한특성이 고려되어야 한다. 본 논문에서는 운동량 고유상태들을 중첩하여 Bessel 빔 해를 구하였는데, 이 때스핀은 나선도 고유상태이거나 빔의 중심축과 일정한 각도를 이루도록 하였다. 규격화를 위한 가우시안싸개함수를 도입하여 스핀, 자기모멘트 등의 물리량의 기대값을 구하였고 기존 연구 결과와의 차이점을논의하였다.
민선홍,박차원,조일성,김민호,마숙활,황원택,김경민,박승우,이민용,이교철,이용진,홍봉환 대한방사성의약품학회 2020 Journal of radiopharmaceuticals and molecular prob Vol.6 No.2
In the state of Positronium (Ps), which is an unstable material created by the temporary combination of electrons and positrons, the imaging technology through photo-conversion methodology is emerging as a new research theme under resonance conditions through terahertz electromagnetic waves. Normally, Positronium can be observed in the positron emission computed tomography (PET) process when an unstable, separate state that remains after the pair annihilation of an electron and a positron remains. In this study, terahertz (THz) waves and Cherenkov radiation (CR) are generated using the principle of ponderomotive force in the plasma wakefield acceleration, and electrons and positrons are simultaneously generated by using a relativistic electron beam without using a PET device. We confirm the possibility of Positronium photoconversion technology in terahertz electromagnetic resonance conditions through experimental studies that generate an unstable state. Here, a relativistic electron beam (REB) energy of 0.5 MeV (γ=2) was used, and the terahertz wave frequencies is G-band. Meanwhile, a THz wave mode converting three-stepped axicon lens was used to apply the photoconversion technology. Through this, light emission in the form of a luminescence-converted Bessel beam can be verified. In the future, it can be used complementarily with PET in nuclear medicine in the field of medical imaging.