Beijing Key Laboratory for THz Spectroscopy and Imaging

Beijing, China

Beijing Key Laboratory for THz Spectroscopy and Imaging

Beijing, China
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Wang J.-Z.,CAS Institute of Physics | Huang Q.-L.,CAS Institute of Physics | Xu X.,CAS Institute of Physics | Quan B.-G.,CAS Institute of Physics | And 6 more authors.
Chinese Physics B | Year: 2015

Based on the facts that multijunction solar cells can increase the efficiency and concentration can reduce the cost dramatically, a special design of parallel multijunction solar cells was presented. The design employed a diffractive optical element (DOE) to split and concentrate the sunlight. A rainbow region and a zero-order diffraction region were generated on the output plane where solar cells with corresponding band gaps were placed. An analytical expression of the light intensity distribution on the output plane of the special DOE was deduced, and the limiting photovoltaic efficiency of such parallel multijunction solar cells was obtained based on Shockley-Queisser's theory. An efficiency exceeding the Shockley-Queisser limit (33%) can be expected using multijunction solar cells consisting of separately fabricated subcells. The results provide an important alternative approach to realize high photovoltaic efficiency without the need for expensive epitaxial technology widely used in tandem solar cells, thus stimulating the research and application of high efficiency and low cost solar cells. © 2015 Chinese Physical Society and IOP Publishing Ltd.


Ye J.-S.,Capital Normal University | Ye J.-S.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Mei G.-A.,Capital Normal University | Mei G.-A.,Beijing Key Laboratory for THz Spectroscopy and Imaging | And 3 more authors.
Journal of Lightwave Technology | Year: 2013

In this paper, a monotonic-increasing-thickness model (MITM) is proposed for designing cylindrically diffractive focusing micromirrors (DFMs) and cylindrically diffractive focusing micromirror arrays (arrayed DFMs). Based on rigorous electromagnetic theory and the boundary element method, numerical results reveal that focal properties of the designed DFMs are significantly improved through replacing the traditional equal-thickness model (ETM) with the proposed MITM, especially in the case of small f -numbers. In addition, the superiority of the MITM to the ETM is demonstrated in designs of the arrayed DFMs. For interference effect in the arrayed DFMs, we present new explanations. © 1983-2012 IEEE.


Ye J.-S.,Capital Normal University | Ye J.-S.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Wang J.-Z.,CAS Institute of Physics | Huang Q.-L.,CAS Institute of Physics | And 4 more authors.
Chinese Physics B | Year: 2013

In this paper, a novel method is proposed and employed to design a single diffractive optical element (DOE) for implementing spectrum-splitting and beam-concentration (SSBC) functions simultaneously. We develop an optimization algorithm, through which the SSBC DOE can be optimized within an arbitrary thickness range according to the limitations of modern photolithography technology. Theoretical simulation results reveal that the designed SSBC DOE has a high optical focusing efficiency. It is expected that the designed SSBC DOE should have practical applications in high-efficiency solar cell systems. © 2013 Chinese Physical Society and IOP Publishing Ltd.


Mei G.-A.,Capital Normal University | Mei G.-A.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Ye J.-S.,Capital Normal University | Ye J.-S.,Beijing Key Laboratory for THz Spectroscopy and Imaging | And 3 more authors.
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2011

Using a general focal-length function, two-dimensional long-focal-depth (LFD) metallic cylindrical focusing micromirrors (MCFMs) are designed and the focal performance is systematically investigated based on rigorous electromagnetic theory and the boundary element method. For a positive preset focal depth, simulation results reveal that the designed MCFMs still possess an LFD property and high lateral resolution even when the f-number is reduced to f =0:3. On the other hand, through setting the preset focal depth to be negative, increased lateral resolution is obtained, compared with the conventional MCFM. In addition, under multiwavelength illumination, a large common LFD region is demonstrated for the designed LFD MCFMs, which is due to the intrinsic achromatic property of reflective systems. © 2011 Optical Society of America.


Xie L.-J.,Capital Normal University | Xie L.-J.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Ye J.-S.,Capital Normal University | Ye J.-S.,Beijing Key Laboratory for THz Spectroscopy and Imaging | And 14 more authors.
Optics Communications | Year: 2014

The flattened Gaussian apodization technique is employed to suppress the axial intensity oscillations, when a plane wave diffracts from a circular hole. Under different apodization parameters, the field intensities are simulated by the complete Rayleigh-Sommerfeld method in the scalar diffraction domain. Numerical results reveal that the axial intensity is uniform in a considerably long propagating range, within which the transverse intensity is also maintained stably. In addition, the flattened Gaussian apodization technique performs well in a wide wavelength band. It is expected to have many practical applications in optical coupling and optical communication systems. © 2014 Elsevier B.V.


Ye J.-S.,Capital Normal University | Ye J.-S.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Zhang Y.,Capital Normal University | Zhang Y.,Beijing Key Laboratory for THz Spectroscopy and Imaging
Optics Communications | Year: 2010

In this paper, we propose a kind of metallic cylindrical focusing micromirrors (MCFMs) with parabolic profiles, and the focal performance is investigated based on rigorous electromagnetic theory and the boundary element method (BEM). Numerical results by the BEM show that the proposed MCFM possesses a high diffraction efficiency and axially achromatic aberration. In addition, through designing a modulating phase function, the MCFM holds long focal depth and high transverse resolution simultaneously. It is believed that the MCFM should have wide application prospects in micro-optical systems, such as micro solar concentrators. © 2009 Elsevier B.V. All rights reserved.


Mei G.-A.,Capital Normal University | Mei G.-A.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Ye J.-S.,Capital Normal University | Ye J.-S.,Beijing Key Laboratory for THz Spectroscopy and Imaging | And 2 more authors.
Optik | Year: 2013

A dual-metallic-cylindrical-focusing-micromirror array (DFMA) with long focal depth (LFD) is designed, and the focusing properties are investigated. Rigorous electromagnetic theory and the boundary element method are employed in our analysis. Many focusing properties, such as the actual focal depth and relative focal depth on the axial plane, together with the focal spot size and diffraction efficiency on the real focal plane are characterized. For TE incident polarization, simulation results reveal that the designed LFD DFMA can exhibit LFD functions. Through comparison with the LFD single-metallic-focusing- micromirror (SFM), interference effect in the LFD DFMA is disclosed. When the preset focal depth of the LFD DFMA is increased, the interference effect between the dual micromirrors is enhanced, which makes the LFD DFMA behave differently from the LFD SFM. © 2012 Elsevier GmbH. All rights reserved.


He J.-W.,Capital Normal University | He J.-W.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Mei G.-A.,Capital Normal University | Mei G.-A.,Beijing Key Laboratory for THz Spectroscopy and Imaging | And 8 more authors.
Journal of Modern Optics | Year: 2013

An amplitude-phase modulation method (APMM) is applied to realize the uniform long-focal-depth (LFD) function of metallic cylindrical focusing micromirrors (MCFMs). Based on rigorous electromagnetic theory and the boundary element method, focal properties of the designed MCFMs are characterized, which contain the actual focal depth, the focal spot size, the normalized encircled energy, the real focal length, and the axial intensity uniformity. On appropriately choosing the incident amplitude distribution with apodization, the designed MCFMs demonstrate the LFD properties with uniform intensity distributions. The superiority of the APMM to the pure phase modulation method is revealed in achieving a higher normalized encircled energy. © 2013 Taylor & Francis Group, LLC.


He J.-W.,Capital Normal University | He J.-W.,Beijing Key Laboratory for THz Spectroscopy and Imaging | Mei G.-A.,Capital Normal University | Mei G.-A.,Beijing Key Laboratory for THz Spectroscopy and Imaging | And 4 more authors.
Optics Communications | Year: 2013

Through changing various parameters, the validity range of the improved Rayleigh-Sommerfeld method (IRSM) in analyzing metallic cylindrical focusing micromirrors (MCFMs) is studied in detail. Focal properties of the MCFMs including the focal spot size, diffraction efficiency, and real focal position are calculated by the IRSM. Rigorous performance results by the boundary element method are also presented as an accurate reference. Numerical results reveal that the IRSM performs well for cylindrically continuous micromirrors even when the f-number decreases to f/0.25. In addition, it is found that for continuous micromirrors the IRSM validity range is insensitive to the incident wavelength and the material refractive indices. However, for continuously diffractive or multilevel diffractive micromirrors, the IRSM is no longer valid when the f-number is less than f/1.0. © 2012 Elsevier B.V.

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