研究目的
To study vortex beam generation by a nanometer spiral slit and explore the rule for the variation of topological charge of the vortex field with the propagation distance.
研究成果
The study verifies the dependence of the topological charge of the optical vortex on the shape of the spiral slit, the handedness of the incident circularly polarized light, and the propagation distance. It enables manipulation of optical vortex generation and selection of appropriate topological charge by adjusting observation distance, facilitating applications in optical trapping, communication, and imaging.
研究不足
The low transmission efficiency of the proposed vortex generator may be improved by widening the slit. The exact position of the optical vortex with integer topological charge is difficult to locate due to the precision limit of the moving platform.
1：Experimental Design and Method Selection:
The study uses theoretical analysis based on scalar diffraction theory, numerical simulations using finite-difference time-domain technique, and experimental measurements with an interferometric setup to investigate the generation and propagation of vortex beams with variable topological charge from a spiral slit.
2：Sample Selection and Data Sources:
A spiral slit etched on a silver film deposited on a glass substrate is used as the sample. Parameters include initial radius r0 = 6 μm, geometric charge l = 4, slit width w = 200 nm, and illumination wavelength λ = 0.633 μm.
3：633 μm. List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes a He-Ne laser, quarter-wave plate, beam splitters, microscope objectives, mirrors, dense filter, charge-coupled device (CCD), moving platform, magnetron sputtering system, focused ion beam etching system, and scanning electron microscopy (SEM). Materials include silver film and glass substrate.
4：Experimental Procedures and Operational Workflow:
For the experiment, linearly polarized light from a He-Ne laser is converted to circularly polarized light, split into object and reference beams, impinged on the sample, magnified by objectives, and interfered to measure topological charge. The sample is fabricated using magnetron sputtering and focused ion beam etching, and its diffraction is tested at various propagation distances by shifting the sample.
5：Data Analysis Methods:
Topological charge is extracted from transverse phase distributions and interference patterns (fork fringes). Theoretical predictions are compared with numerical simulations and experimental results.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容-
He-Ne laser
Provides linearly polarized light source for the experiment
-
Quarter-wave plate
Converts linearly polarized light to circularly polarized light
-
Beam splitter
Splits the light beam into object and reference parts
-
Microscope objective
60x
Magnifies the transmission field for observation
-
Charge-coupled device
Receives and captures the light field for measurement
-
Moving platform
Allows precise shifting of the sample to vary propagation distance
-
Magnetron sputtering system
Deposits silver film on glass substrate
-
Focused ion beam etching system
Etches the spiral slit on the silver film
-
Scanning electron microscopy
Images the fabricated spiral slit
-
登录查看剩余7件设备及参数对照表
查看全部
