scholarly journals Parametric Wavelength Conversion From Conventional Near-Infrared to Visible Band

2006 ◽  
Vol 18 (23) ◽  
pp. 2445-2447 ◽  
Author(s):  
R. Jiang ◽  
R. Saperstein ◽  
N. Alic ◽  
M. Nezhad ◽  
C. McKinstrie ◽  
...  
Keyword(s):  
Near Infrared ◽  
Wavelength Conversion ◽  
Visible Band

Tunable wavelength conversion based on a nanoscale slot waveguide in communication bands

2020 ◽  
Vol 34 (25) ◽  
pp. 2050260
Author(s):  
Rujing Guo ◽  
Mengxiong Han ◽  
Peiqi Wei ◽  
Shenwei Yin ◽  
Yan Ma
Keyword(s):  
Signal Processing ◽  
Near Infrared ◽  
Wavelength Conversion ◽  
Processing System ◽  
Geometric Dimension ◽  
Pulse Generation ◽  
Complex Signal ◽  
Slot Waveguide ◽  
Signal Processing System ◽  
Tunable Wavelength

This paper introduces a new nanoscale slot waveguide using organic material, graphene, and silicon-based materials. The physical mechanism of additional biased voltage can improve the performance of graphene-related waveguide, the proposed waveguide exhibits tunable performance including effective refractive index and dispersion without changing its structure and geometric dimension, which contributes to the practical value in future complex signal processing system. Based on the waveguide, wavelength conversion based on four-wave mixing is theoretically investigated in the near-infrared region and the tunable wavelength conversion is realized. These research results will have potential in the fields of data transmission and optical communications and help researchers deeply understand the physical mechanisms and nonlinear effects about the optical pulse generation processes and signal processing.

Coherent near-infrared wavelength conversion in semiconductor quantum cascade lasers

2006 ◽  
Vol 89 (18) ◽  
pp. 183507 ◽  
Author(s):  
C. Zervos ◽  
M. D. Frogley ◽  
C. C. Phillips ◽  
D. O. Kundys ◽  
L. R. Wilson ◽  
...  
Keyword(s):  
Near Infrared ◽  
Wavelength Conversion ◽  
Quantum Cascade Lasers ◽  
Infrared Wavelength ◽  
Quantum Cascade ◽  
Cascade Lasers

Air Dustfall Impact on Spectrum of Ficus Microcarpa’s Leaf

2013 ◽  
Vol 655-657 ◽  
pp. 813-815 ◽  
Author(s):  
Jin Hong Xu ◽  
Jin Ting Yu
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Leaf Surface ◽  
Industrial Area ◽  
Infrared Band ◽  
Correlation Relationship ◽  
Guangzhou City ◽  
Visible Band ◽  
Economic Method ◽  
Ficus Microcarpa

This article has studied the correlation relationship between the spectral features of polluted leaf surface of Ficus microcarpa and air dustfall in Guangzhou City. The results show that the spectral reflectance of leaves in the industrial area and large traffic area is 3-5.5% higher than that of leaves in cleaning area in the visible band, but is 10-15% lower in the near infrared band. Compared to the spectral reflectance of the cleaned leaf, the spectral reflectance of leaf on nature dirty is 6.6％ higher in the visible band and 25.6% lower in the infrared band. The spectral reflectance difference between dirty leaf and cleaned leaf in the infrared band has a strong correlation with air dustfall in Guangzhou city. The correlation coefficient is 0.821. It is simple and convenient, fast, economic method to monitor the air dustfall using the spectral characteristic of Ficus microcarpa’s leaf.

scholarly journals Constraint-free wavelength conversion supported by giant optical refraction in a 3D perovskite supercrystal

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Ludovica Falsi ◽  
Luca Tartara ◽  
Fabrizio Di Mei ◽  
Mariano Flammini ◽  
Jacopo Parravicini ◽  
...  
Keyword(s):  
Near Infrared ◽  
Wavelength Conversion ◽  
Single Photon ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Index Of Refraction ◽  
Optical Refraction ◽  
Quasi Phase Matching ◽  
Wave Vector Mismatch ◽  
Focused Beams

Abstract Nonlinear response in a material increases with its index of refraction as n4. Commonly, n ~ 1 so that diffraction, dispersion, and chromatic walk-off limit nonlinear scattering. Ferroelectric crystals with a periodic 3D polarization structure overcome some of these constraints through versatile Cherenkov and quasi-phase-matching mechanisms. Three-dimensional self-structuring can also lead to a giant optical refraction. Here, we perform second-harmonic-generation experiments in KTN:Li in conditions of giant broadband refraction. Enhanced response causes wavelength conversion to occur in the form of bulk Cherenkov radiation without diffraction and chromatic walk-off, even in the presence of strong wave-vector mismatch and highly focused beams. The process occurs with a wide spectral acceptance of more than 100 nm in the near infrared spectrum, an ultra-wide angular acceptance of up to ±40∘, with no polarization selectivity, and can be tuned to allow bulk supercontinuum generation. Results pave the way to highly efficient and adaptable nonlinear optical devices with the promise of single-photon-to-single-photon nonlinear optics.

scholarly journals Influence of Spatial Resolution for Vegetation Indices’ Extraction Using Visible Bands from Unmanned Aerial Vehicles’ Orthomosaics Datasets

2021 ◽  
Vol 13 (16) ◽  
pp. 3238
Author(s):  
Mirko Saponaro ◽  
Athos Agapiou ◽  
Diofantos G. Hadjimitsis ◽  
Eufemia Tarantino
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Spatial Resolution ◽  
Near Infrared ◽  
Vegetation Indices ◽  
Visible Band ◽  
Digital Elevation ◽  
Aerial Vehicle ◽  
High Level ◽  
Areas Of Interest ◽  
Greenness Index

The consolidation of unmanned aerial vehicle (UAV) photogrammetric techniques for campaigns with high and medium observation scales has triggered the development of new application areas. Most of these vehicles are equipped with common visible-band sensors capable of mapping areas of interest at various spatial resolutions. It is often necessary to identify vegetated areas for masking purposes during the postprocessing phase, excluding them for the digital elevation models (DEMs) generation or change detection purposes. However, vegetation can be extracted using sensors capable of capturing the near-infrared part of the spectrum, which cannot be recorded by visible (RGB) cameras. In this study, after reviewing different visible-band vegetation indices in various environments using different UAV technology, the influence of the spatial resolution of orthomosaics generated by photogrammetric processes in the vegetation extraction was examined. The triangular greenness index (TGI) index provided a high level of separability between vegetation and nonvegetation areas for all case studies in any spatial resolution. The efficiency of the indices remained fundamentally linked to the context of the scenario under investigation, and the correlation between spatial resolution and index incisiveness was found to be more complex than might be trivially assumed.

scholarly journals Recent Advances in Graphene-Assisted Nonlinear Optical Signal Processing

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Jian Wang ◽  
Xiao Hu
Keyword(s):  
Signal Processing ◽  
High Speed ◽  
Nonlinear Optical ◽  
Near Infrared ◽  
Wavelength Conversion ◽  
Optical Signal Processing ◽  
Optical Computing ◽  
Optical Signal ◽  
Perfect Absorption ◽  
Nonlinear Optical Signal Processing

Possessing a variety of remarkable optical, electronic, and mechanical properties, graphene has emerged as an attractive material for a myriad of optoelectronic applications. The wonderful optical properties of graphene afford multiple functions of graphene based polarizers, modulators, transistors, and photodetectors. So far, the main focus has been on graphene based photonics and optoelectronics devices. Due to the linear band structure allowing interband optical transitions at all photon energies, graphene has remarkably large third-order optical susceptibilityχ(3), which is only weakly dependent on the wavelength in the near-infrared frequency range. The graphene-assisted four-wave mixing (FWM) based wavelength conversions have been experimentally demonstrated. So, we believe that the potential applications of graphene also lie in nonlinear optical signal processing, where the combination of its unique largeχ(3)nonlinearities and dispersionless over the wavelength can be fully exploited. In this review article, we give a brief overview of our recent progress in graphene-assisted nonlinear optical device and their applications, including degenerate FWM based wavelength conversion of quadrature phase-shift keying (QPSK) signal, phase conjugated wavelength conversion by degenerate FWM and transparent wavelength conversion by nondegenerate FWM, two-input and three-input high-base optical computing, and high-speed gate-tunable terahertz coherent perfect absorption (CPA) using a split-ring graphene.

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