In this paper, we present the spatial beam modulator based on electrowetting liquid lens/prism array, in order to realize adjustment of various beams (parallel, convergent, divergent) in three-dimensional space. To calculating the adjustments range of the spatial beam modulator, the optical transfer function (OTF) is derived, according to the theories of geometrical optics, matrix optics and electrowetting. We also establish the simulation model for verifying the correctness of OTF by COMSOL. The results show that the spatial beam modulator can translate, expand, contract, converge and diverge the parallel beam. When the parallel beam is incident on the spatial beam modulator, the maximum translation distance of parallel beam is 0.92mm, and its focal length f can be adjusted in the range of 7.96 mm to ∞ (dual-convex liquid interface) or -∞ to 25.99 mm (dual-concave interface). In addition, the spatial beam modulator can also collimate, converge, diverge the convergent beam or divergence beam.
In this paper, an electrowetting-based prism-arrays system is proposed to be non-mechanical beam deflection controller in the three-dimensional space. The system is composed of five liquid prism units arranged at equal intervals in a cross shape. The relationship between beam deflection angle, electrowetting contact angle, and liquid refractive index are derived. The influence of electrowetting saturation, liquid refractive index, and interval between adjacent prisms on the performance of prism-arrays system are simulated in COMSOL, where the length and width of each prism are set to 3mm, and the height is set to 6mm. The shape of the liquid interface in liquid prism and its deflection are analyzed. The results show that the system succeed to achieve continuous control of beam deflection within a certain range, and the beam deflection angle of this arrayed liquid prisms is from -20° to 20° when 1-chloronaphthalene oil and 1% Nacl aqueous solution with sodium benzoate are filled in the liquid prisms. The smaller interval between adjacent prisms can increase the beam control range of the system. However, the liquid prism unit has a certain size, so the interval cannot be infinitely small. As the interval is set to 9mm, the steering region of the prism-arrays system is in a conical region with an apex angle of 40°, and the vertex of the circular cone is located at the 22.05mm in the z-axis. The proposed system will promote the development of nonmechanical beam deflection technology and have a wide range of applications.
This paper introduces radial multi-sub-mirror (MSM) synthetic aperture system structure and imaging characteristics of the liquid lens based, and the MSM array for the simulate imaging and image restoration. In order to obtain the scaling invariance of MSM system imaging, the dimensionless method is used to reduce the structural parameters. Baseline statistical distribution diagram and modulation transfer function (MTF) are used to analyze the structural characteristics and intermediate frequency(IF) characteristics. The MSM optical characteristics are calculated and the raw image is simulated under different filling factors. For the reduction of the IF characteristics of the synthetic aperture system, the raw image is restored by Wiener filtering. Using the standard deviation and peak signal-to-noise ratio between the synthetic aperture imaging system and the filled aperture imaging system, these two indicators evaluate the image quality with different fill factors. A comparative analysis of the restored images yields a relationship between filling factor and image quality. Since the large number of sub-mirrors in the MSM array, resulting in a larger number of different baselines. Because the baseline corresponds to the distribution characteristics of spatial frequency, the baseline of the MSM has a large number of repeats in the IF region, so the structure has a good response of IF. The results showed that as the sub-aperture diameter increases, the imaging quality of the MSM structure becomes better. The image restoration effect enhance with the increase of the filling factor. After wiener filtering, the image quality is improved.
Transmittance spectra of double-sided teeth-shaped nanoplasmonic waveguide filters formed in the metal-insulator-metal (MIM) waveguides are systematically investigated. It is found that a staggered double-sided teeth-shaped structure exhibits a wide and sharp bandgap, furthermore the two staggered double teeths combination can realize the narrow band filter with ultracompact size in the length of a few hundred nanometers. The finite element method is employed in the simulations. Our results may open a way to construct nanoscale waveguide filters for high-density nanoplasmonic integration circuits.
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