scholarly journals Influence of Anodization Temperature on Geometrical and Optical Properties of Porous Anodic Alumina(PAA)-Based Photonic Structures

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3185 ◽  
Author(s):  
Ewelina Białek ◽  
Maksymilian Włodarski ◽  
Małgorzata Norek
Keyword(s):  
Optical Properties ◽  
Pulse Sequence ◽  
High Refractive Index ◽  
High Potential ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector ◽  
Mid Infrared ◽  
Steady Current ◽  
Wide Range ◽  
Subsequent Application

In this work, the influence of a wide range anodizing temperature (5–30 °C) on the growth and optical properties of PAA-based distributed Bragg reflector (DBR) was studied. It was demonstrated that above 10 °C both structural and photonic properties of the DBRs strongly deteriorates: the photonic stop bands (PSBs) decay, broaden, and split, which is accompanied by the red shift of the PSBs. However, at 30 °C, new bands in transmission spectra appear including one strong and symmetric peak in the mid-infrared (MIR) spectral region. The PSB in the MIR region is further improved by a small modification of the pulse sequence which smoothen and sharpen the interfaces between consecutive low and high refractive index layers. This is a first report on PAA-based DBR with a good quality PSB in MIR. Moreover, it was shown that in designing good quality DBRs a steady current recovery after subsequent application of high potential (UH) pulses is more important than large contrast between low and high potential pulses (UH-UL contrast). Smaller UH-UL contrast helps to better control the current evolution during pulse anodization. Furthermore, the lower PSB intensity owing to the smaller UH-UL contrast can be partially compensated by the higher anodizing temperature.

scholarly journals A highly distributed Bragg stack with unique geometry provides effective camouflage for Loliginid squid eyes

2011 ◽  
Vol 8 (63) ◽  
pp. 1386-1399 ◽  
Author(s):  
Amanda L. Holt ◽  
Alison M. Sweeney ◽  
Sönke Johnsen ◽  
Daniel E. Morse
Keyword(s):  
Self Assembly ◽  
Specular Reflection ◽  
High Refractive Index ◽  
Biochemical Properties ◽  
Bragg Reflector ◽  
Silver Layer ◽  
Distributed Bragg Reflector ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Visible Wavelengths

Cephalopods possess a sophisticated array of mechanisms to achieve camouflage in dynamic underwater environments. While active mechanisms such as chromatophore patterning and body posturing are well known, passive mechanisms such as manipulating light with highly evolved reflectors may also play an important role. To explore the contribution of passive mechanisms to cephalopod camouflage, we investigated the optical and biochemical properties of the silver layer covering the eye of the California fishery squid, Loligo opalescens . We discovered a novel nested-spindle geometry whose correlated structure effectively emulates a randomly distributed Bragg reflector (DBR), with a range of spatial frequencies resulting in broadband visible reflectance, making it a nearly ideal passive camouflage material for the depth at which these animals live. We used the transfer-matrix method of optical modelling to investigate specular reflection from the spindle structures, demonstrating that a DBR with widely distributed thickness variations of high refractive index elements is sufficient to yield broadband reflectance over visible wavelengths, and that unlike DBRs with one or a few spatial frequencies, this broadband reflectance occurs from a wide range of viewing angles. The spindle shape of the cells may facilitate self-assembly of a random DBR to achieve smooth spatial distributions in refractive indices. This design lends itself to technological imitation to achieve a DBR with wide range of smoothly varying layer thicknesses in a facile, inexpensive manner.

Optical Properties of Alq3/TiO2 BDR Structure Processed by Spin Coating Technique

MRS Advances ◽  
2019 ◽  
Vol 4 (11-12) ◽  
pp. 661-666
Author(s):  
L. Ajith DeSilva ◽  
Sarahn Nazaret ◽  
A. G. U. Perera ◽  
T. M. W. J. Bandara
Keyword(s):  
Thin Films ◽  
Titanium Dioxide ◽  
Optical Properties ◽  
Band Gap ◽  
Spin Coating ◽  
Light Emission ◽  
Wide Band ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector ◽  
Pl Quenching

ABSTRACTOne-dimensional hybrid Distributed Bragg Reflector (DBR) is constructed using Tris (8-hydroxy) quinoline aluminum (Alq3) molecules and Titanium dioxide (TiO2) nanoparticles via spin coating process. Light emission from thin films of low molecular weight organic semiconductor of Alq3 is dominated by excitons. This material has been widely used as a superior emitter for organic light emitting diodes. Titanium dioxide (TiO2) is an inorganic semiconductor with a high band gap. Photoluminescence (PL) of thin films of Alq3 showed a broad PL peak at 530 nm. In DBR structures, PL quenching is observed but there is no shift in the PL peak of the Alq3. The PL quenching is tentatively attributed to energy transfer via sensitization to wide band gap TiO2 layers. A simple excitonic model is suggested to explain the observation. Fabrication process and optical properties of the structure are presented.

scholarly journals Extended bound states in the continuum in a one-dimensional grating implemented on a distributed Bragg reflector

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Emilia Pruszyńska-Karbownik ◽  
Mikołaj Janczak ◽  
Tomasz Czyszanowski
Keyword(s):  
Refractive Index ◽  
Bound States ◽  
High Refractive Index ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector ◽  
Optical Cavities ◽  
One Dimensional ◽  
Optical Modes ◽  
High Degree ◽  
The Continuum

Abstract Bound states in the continuum (BICs) are observed in optical cavities composed of a high refractive index periodic structure embedded in significantly lower refractive index surroundings, enabling vertical confinement of the grating modes. Here, we propose a vertically nonsymmetric configuration, implemented on a high refractive index bulk substrate with a one-dimensional grating positioned on a distributed Bragg reflector (DBR). In this configuration, the grating modes are leaky, which could prohibit the creation of a BIC if the grating was implemented on uniform substrate. However, the judiciously designed DBR on which the grating is implemented reflects nonzero diffraction orders induced by the grating. We found that the laterally antisymmetric optical modes located at the center of the Brillouin zone of this structure create BICs that are robust against changes in the grating parameters, as long as the DBR reflects the diffraction orders. The configuration enables a high degree of design freedom, facilitating the realization of very high quality factor cavities in conventional all-semiconductor technology.

scholarly journals Broadband Optical Properties of Atomically Thin PtS2 and PtSe2

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3269
Author(s):  
Georgy A. Ermolaev ◽  
Kirill V. Voronin ◽  
Mikhail K. Tatmyshevskiy ◽  
Arslan B. Mazitov ◽  
Aleksandr S. Slavich ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Transition Metal Dichalcogenides ◽  
Optoelectronic Device ◽  
High Refractive Index ◽  
Broadband Absorption ◽  
Wide Range ◽  
Out Of Plane ◽  
Metal Dichalcogenides ◽  
Infrared Wavelengths

Noble transition metal dichalcogenides (TMDCs) such as PtS2 and PtSe2 show significant potential in a wide range of optoelectronic and photonic applications. Noble TMDCs, unlike standard TMDCs such as MoS2 and WS2, operate in the ultrawide spectral range from ultraviolet to mid-infrared wavelengths; however, their properties remain largely unexplored. Here, we measured the broadband (245–3300 nm) optical constants of ultrathin PtS2 and PtSe2 films to eliminate this gap and provide a foundation for optoelectronic device simulation. We discovered their broadband absorption and high refractive index both theoretically and experimentally. Based on first-principle calculations, we also predicted their giant out-of-plane optical anisotropy for monocrystals. As a practical illustration of the obtained optical properties, we demonstrated surface plasmon resonance biosensors with PtS2 or PtSe2 functional layers, which dramatically improves sensor sensitivity by 60 and 30%, respectively.

Fabrication and optical properties of non-polar III-nitride air-gap distributed Bragg reflector microcavities

2013 ◽  
Vol 103 (20) ◽  
pp. 201118 ◽  
Author(s):  
Renchun Tao ◽  
Munetaka Arita ◽  
Satoshi Kako ◽  
Yasuhiko Arakawa
Keyword(s):  
Optical Properties ◽  
Air Gap ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector

Mid-infrared quantum cascade laser integrated with distributed Bragg reflector

2016 ◽  
Author(s):  
Hiroyuki Yoshinaga ◽  
Jun-ichi Hashimoto ◽  
Hiroki Mori ◽  
Yukihiro Tsuji ◽  
Makoto Murata ◽  
...  
Keyword(s):  
Quantum Cascade Laser ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector ◽  
Mid Infrared ◽  
Quantum Cascade
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