Design of Energy Selective Surfaces with Wide Reflection Band

2019 ◽  
Author(s):  
Dongmei Qin ◽  
Wenmei Zhang
Keyword(s):  
Reflection Band

scholarly journals 1.1-µm Band Extended Wide-Bandwidth Wavelength-Swept Laser Based on Polygonal Scanning Wavelength Filter

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3053
Author(s):  
Gi Hyen Lee ◽  
Soyeon Ahn ◽  
Jinhwa Gene ◽  
Min Yong Jeon
Keyword(s):  
Optical Amplifiers ◽  
Dynamic Change ◽  
Cholesteric Liquid Crystal ◽  
Average Power ◽  
Semiconductor Optical Amplifiers ◽  
Scanning Speed ◽  
Reflection Band ◽  
First Order ◽  
Wavelength Filter ◽  
Buildup Time

We demonstrated a 1.1-µm band extended wideband wavelength-swept laser (WSL) that combined two semiconductor optical amplifiers (SOAs) based on a polygonal scanning wavelength filter. The center wavelengths of the two SOAs were 1020 nm and 1140 nm, respectively. Two SOAs were connected in parallel in the form of a Mach-Zehnder interferometer. At a scanning speed of 1.8 kHz, the 10-dB bandwidth of the spectral output and the average power were approximately 228 nm and 16.88 mW, respectively. Owing to the nonlinear effect of the SOA, a decrease was observed in the bandwidth according to the scanning speed. Moreover, the intensity of the WSL decreased because the oscillation time was smaller than the buildup time. In addition, a cholesteric liquid crystal (CLC) cell was fabricated as an application of WSL, and the dynamic change of the first-order reflection of the CLC cell in the 1-µm band was observed using the WSL. The pitch jumps of the reflection band occurred according to the electric field applied to the CLC cell, and instantaneous changes were observed.

scholarly journals Двумерные брэгговские резонаторы на основе планарных диэлектрических волноводов (от теории к модельному тестированию)

2019 ◽  
Vol 53 (10) ◽  
pp. 1315
Author(s):  
Н.С. Гинзбург ◽  
Н.Ю. Песков ◽  
В.Ю. Заславский ◽  
Е.Р. Кочаровская ◽  
А.М. Малкин ◽  
...  
Keyword(s):  
Narrow Band ◽  
Bragg Reflection ◽  
Dielectric Waveguides ◽  
Wavelength Band ◽  
Reflection Band ◽  
Millimeter Wavelength ◽  
Bragg Structures ◽  
Significant Interest ◽  
Simulation Results ◽  
Analytical Approaches

Using analytical approaches and CST Microwave Studio 3D simulations, we have undertaken a theoretical analysis of electrodynamical characteristics of 2D Bragg structures based on planar oversized dielectric waveguides with double-periodical corrugation. Such structures are of significant interest for obtaining directed narrow-band radiation in heterolasers with large dimensions of an active area. Modeling electrodynamical experiments on 'cold' testing of such structures in millimeter wavelength band were conducted. Fine agreement between the experimental results and the simulation results was demonstrated which includes the presence of the highest-quality mode inside the Bragg reflection band in absence of the periodicity defects.

Helicopter-borne ground-penetrating radar investigations on temperate alpine glaciers: A comparison of different systems and their abilities for bedrock mapping

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA119-WA129 ◽  
Author(s):  
Anja Rutishauser ◽  
Hansruedi Maurer ◽  
Andreas Bauder
Keyword(s):  
Ground Penetrating Radar ◽  
Low Frequency ◽  
Large Data ◽  
Internal Reflection ◽  
Swiss Alps ◽  
Reflection Band ◽  
Data Set ◽  
Investigation Area ◽  
Attractive Option ◽  
Ground Penetrating

On the basis of a large data set, comprising approximately 1200 km of profile lines acquired with different helicopter-borne ground-penetrating radar (GPR) systems over temperate glaciers in the western Swiss Alps, we have analyzed the possibilities and limitations of using helicopter-borne GPR surveying to map the ice-bedrock interface. We have considered data from three different acquisition systems including (1) a low-frequency pulsed system hanging below the helicopter (BGR), (2) a stepped frequency system hanging below the helicopter (Radar Systemtechnik GmbH [RST]), and (3) a commercial system mounted directly on the helicopter skids (Geophysical Survey Systems Incorporated [GSSI]). The systems showed considerable differences in their performance. The best results were achieved with the BGR system. On average, the RST and GSSI systems yielded comparable results, but we observed significant site-specific differences. A comparison with ground-based GPR data found that the quality of helicopter-borne data is inferior, but the compelling advantages of airborne surveying still make helicopter-borne data acquisition an attractive option. Statistical analyses concerning the bedrock detectability revealed not only large differences between the different acquisition systems but also between different regions within our investigation area. The percentage of bedrock reflections identified (with respect to the overall profile length within a particular region) varied from 11.7% to 68.9%. Obvious factors for missing the bedrock reflections included large bedrock depths and steeply dipping bedrock interfaces, but we also observed that internal features within the ice body may obscure bedrock reflections. In particular, we identified a conspicuous “internal reflection band” in many profiles acquired with the GSSI system. We attribute this feature to abrupt changes of the water content within the ice, but more research is required for a better understanding of the nature of this internal reflection band.

Enhanced reflection band broadening in polymer stabilized cholesteric liquid crystals with negative dielectric anisotropy

2018 ◽  
Vol 267 ◽  
pp. 120-126 ◽  
Author(s):  
Hossein Nemati ◽  
Shiyi Liu ◽  
Alireza Moheghi ◽  
Vincent P. Tondiglia ◽  
Kyung Min Lee ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Dielectric Anisotropy ◽  
Band Broadening ◽  
Cholesteric Liquid Crystals ◽  
Reflection Band ◽  
Polymer Stabilized

Direction-Independent Band Gaps Extension Based on Thue-Morse Photonic Heterostructures Containing Negative-Index Materials

2011 ◽  
Vol 675-677 ◽  
pp. 1077-1080 ◽  
Author(s):  
Ou Yang Hong ◽  
Xin Hua Deng
Keyword(s):  
Optical Fibers ◽  
Transverse Electric ◽  
Negative Index ◽  
Reflection Band ◽  
Negative Index Materials ◽  
One Dimensional ◽  
Fabry Perot ◽  
Potential Applications ◽  
New Type ◽  
Positive Index

The band structure and photonic spectrum of one dimensional Thue-Morse quasicrystal composed by negative-index materials and positive-index materials are studied. We show that a new type of the omnidirectional reflection band (ORB) exists in Thue-Morse photonic heterostructures. Compared to a single Thue-Morse quasicrystal, the frequency range of the ORB in a Thue-Morse photonic heterostructure can be notably enlarged, and the width and location of the ORB do not change with Thue-Morse order. The lower edge of the ORB depends only on transverse electric (TE) polarization, while the higher edge of the ORB depends only on transversemagnetic (TM) polarization. These results imply potential applications in improving planar microcavities, optical fibers, and Fabry–Perot resonators, etc.

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