Nonlinear Absorption Properties of Spherical Gold Colloidal Nanoparticles

2012 ◽  
Vol 476-478 ◽  
pp. 923-927 ◽  
Author(s):  
Chan Zheng ◽  
Xiao Yun Ye ◽  
Xue Qing Xiao
Keyword(s):  
Nonlinear Absorption ◽  
Laser Pulses ◽  
Phase Method ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Colloidal Nanoparticles ◽  
Free Carrier Absorption ◽  
Absorption Properties ◽  
Liquid Phase Method ◽  
Carrier Absorption

Spherical gold colloidal nanoparticles were prepared used traditional liquid phase method and the corresponding nonlinear absorption properties were investigated by open aperture Z-scan technique using 8 ns laser pulses of 532 nm. The gold colloidal nanoparticles exhibited a transform from saturable absorption (SA) to reverse saturable absorption (RSA) at relatively higher irradiation intensities. The SA behavior presumably owes to the bleach of ground-state surface plasmon resonance (SPR) absorption, while the RSA might result from high excited-stated free carrier absorption.

scholarly journals Effect of Size on the Saturable Absorption and Reverse Saturable Absorption in Silver Nanoparticle and Ultrafast Dynamics at 400 nm

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Sandeep Kumar Maurya ◽  
Anuradha Rout ◽  
Rashid A. Ganeev ◽  
Chunlei Guo
Keyword(s):  
Nonlinear Absorption ◽  
Laser Pulses ◽  
Acoustic Vibration ◽  
Radial Breathing Mode ◽  
Femtosecond Laser Pulses ◽  
Photon Absorption ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Ultrafast Dynamics ◽  
Ag Nps

Saturable absorption and reverse saturable absorption play an important role in the studies of the nonlinear optical properties of nanoparticles at resonant excitation. With this viewpoint, nonlinear absorption processes of chemically prepared silver nanoparticles in deionized water were studied using femtosecond laser pulses at 400 nm. Our nonlinear absorption study shows that there is competition between saturable absorption and two-photon absorption in prepared Ag NPs which depends on the size of the nanoparticles. We have also studied the ultrafast dynamics associated with nanoparticles which also results in the direct correlation between the ultrafast timescale and the size of the nanoparticle. The excitation of Ag NPs at 400 nm has shown the manifestation of damped oscillation which is attributed to the radial breathing mode oscillation due to acoustic vibration.

Picosecond and femtosecond optical nonlinearities of novel corroles

2012 ◽  
Vol 16 (01) ◽  
pp. 140-148 ◽  
Author(s):  
Syed Hamad ◽  
Surya P. Tewari ◽  
L. Giribabu ◽  
S. Venugopal Rao
Keyword(s):  
Nonlinear Absorption ◽  
Nonlinear Optical ◽  
Laser Pulses ◽  
Photon Absorption ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Closed Aperture ◽  
Absorption Data ◽  
Time Domains ◽  
Fs Laser

We present our results from the experimental and modeling studies of picosecond (ps) and femtosecond (fs) nonlinearities of two novel corroles (a) tritolyl corrole (TTC) (b) triphenyl corrole (TPC) using the Z-scan technique. Both open and closed aperture Z-scan curves were recorded with ~2 ps/~40 fs laser pulses at a wavelength of 800 nm and nonlinear optical coefficients were extracted for both studies. Both the molecules possessed negative nonlinear refractive index (n2) as revealed by signature of the closed aperture data in both (ps and fs) time domains. Picosecond nonlinear absorption data of TPC obtained at a concentration of 5 × 10-4 M demonstrated complex behavior with switching from reverse saturable absorption (RSA) within saturable absorption (SA) at lower peak intensities to RSA at higher peak intensities. TTC data recorded at the similar concentration exhibited saturable absorption (SA) type of behavior at lower peak intensities to switching from RSA with in SA at higher peak intensities. At a concentration of 2.5 × 10-4 M, the ps open aperture data at higher peak intensities illustrated effective three-photon absorption (3PA) for both the molecules. We also report the picosecond spectral dependent Z-scan studies performed at 680 nm, 700 nm, and 740 nm. Nonlinear absorption and refraction of both the samples at these three wavelengths were studied in detail. Femtosecond nonlinear absorption data of TPC and TTC demonstrated the behavior of saturable absorption (SA) at a concentration of 1 × 10-3 M. Solvent contribution to the nonlinearity was also identified. We have also evaluated the sign and magnitude of third order nonlinearity. We discuss the nonlinear optical performance of these organic molecules.

Optimization of Reverse Saturable Absorber Limiters: Material Requirements and Design Considerations

1994 ◽  
Vol 374 ◽  
Author(s):  
D. J. Hagan ◽  
T. Xia ◽  
A. Dogariu ◽  
A. A. Said ◽  
E. W. Van Stryland
Keyword(s):  
Nonlinear Absorption ◽  
Entire Length ◽  
Nonlinear Material ◽  
Propagation Path ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Individual Element ◽  
Analytic Model ◽  
Molecular Density ◽  
Optimized Distribution

AbstractWe present numerical beam-propagation simulations of optimized reverse-saturable absorption (RSA) based optical limiters where the depth of focus of the input beam is much smaller than the thickness of the nonlinear material. The optimization is achieved by allowing the molecular concentration to vary along the propagation path, allowing the entire length of the limiter to reach the maximum possible nonlinear absorption before eventual damage to the limiter. We review in detail the analytic model originally derived by Miles [1] to determine the design and performance of such limiters. This model requires the usual 5-level model used in the numerical solution to be approximated by a quasi-three-level system. We show that this effective 3-level excited-state cross section is both pulsewidth and fluence dependent. The numerical propagation output shows that there is considerable diffractive beam distortion, which cannot be accounted for in the analytic model. The end result is that while there is qualitative agreement with numerical results, the magnitude of the limited output can be an order-of-magnitude underestimated. We determine that the fluence level at all parts of the limiter must be at least ten times the saturation fluence to efficiently utilize the nonlinear absorption. We further describe how the optimized distribution of molecular density is the limit of the multi-element tandem limiter for an infinite number of elements. By carefully accounting for saturation over the entire length of each individual element, we show how a multi-element limiter may be designed to closely approach the performance of the optimized distribution for as few as four elements. With current materials technology the damage threshold of solid hosts needed to vary the molecular density is much lower than that of glass cuvettes used for liquid based limiters. Therefore, a multi-element liquid based tandem limiter can be used in full saturation so that better limiter performance should be obtained. Ultimately, however, the operation of all RSA-based limiters involves a strict trade-off between performance and linear transmittance.

scholarly journals Recombination and diffusion processes in electronic grade 4H silicon carbide

2019 ◽  
Vol 59 (1) ◽  
Author(s):  
Patrik Ščajev ◽  
Liudvikas Subačius ◽  
Kęstutis Jarašiūnas ◽  
Masashi Kato
Keyword(s):  
Functional Form ◽  
Diffusion Processes ◽  
Laser Pulses ◽  
Free Carrier Absorption ◽  
Temperature Dependent ◽  
Subsequent Decrease ◽  
Recombination Processes ◽  
Carrier Absorption ◽  
And Diffusion ◽  
Trap Activation

Carrier dynamics in n-type 4H-SiC epilayers of varying thicknesses and low Z1/2 defect concentrations are investigated here in wide ranges of excess carrier density and temperature. Several techniques are employed to monitor carrier diffusion and recombination processes, including light induced transient grating (LITG), microwave photoconductance decay (MPCD) and free carrier absorption (FCA) using ps-laser pulses at 355 nm. The observed increase of the diffusion coefficient with the increasing excitation level is explained by the transition from the minority to the bipolar transport regime. Its subsequent decrease with even higher excitations is found to be governed by band-gap renormalization and degeneracy effects. The bulk lifetime, limited by hole traps at 0.19–0.24 eV above the valence band at lower excitations, was found to decrease from few microseconds to hundreds of nanoseconds during the transition regime from the minority to the bipolar transport. Our temperature-dependent measurements confirmed the trap activation energy and provided the approximate functional form of electron and hole lifetimes as τe = 340 × (T/300 K)3/2 ns and τh = 100 × (T/300 K)–1/2 ns, for the temperature T range 80–800 K. It was found to hold for 65 and 120 μm sample thicknesses, while the lifetimes were found to be twice shorter for the sample 35 μm thick.

Graphene/MoS2 organic glasses: Fabrication and enhanced reverse saturable absorption properties

2013 ◽  
Vol 35 (12) ◽  
pp. 2352-2356 ◽  
Author(s):  
Qiuyun Ouyang ◽  
Hailong Yu ◽  
Hongyu Wu ◽  
Zhenyu Lei ◽  
Lihong Qi ◽  
...  
Keyword(s):  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Absorption Properties ◽  
Organic Glasses

Nonlinear absorption in tetrathia[22]porphyrin(2.1.2.1)s: visualizing strong reverse saturable absorption at non-resonant excitation

RSC Advances ◽  
2016 ◽  
Vol 6 (27) ◽  
pp. 22659-22663 ◽  
Author(s):  
Kamaljit Singh ◽  
Shafali Arora ◽  
Krishnandu Makhal ◽  
Paramjit Kaur ◽  
Debabrata Goswami
Keyword(s):  
Nonlinear Absorption ◽  
Potential Application ◽  
Optically Active ◽  
Resonant Excitation ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Threshold Values ◽  
Optical Limiters ◽  
The Family ◽  
New Entry

meso-Substituted neutral, aromatic tetrathia[22]porphyrin(2.1.2.1)s represent a new entry in the family of nonlinear optically active porphyrins. The low fluence threshold values of these porphyrins endorse potential application as optical limiters.

Materials for Reverse Saturable Absorption Optical Limiters

1994 ◽  
Vol 374 ◽  
Author(s):  
James S. Shirk ◽  
Richard G. S. Pong ◽  
Steven R. Flom ◽  
Michael E. Boyle ◽  
Arthur W. Snow
Keyword(s):  
Molecular Structure ◽  
Heavy Metal ◽  
Optical Properties ◽  
Nonlinear Absorption ◽  
Nonlinear Optical ◽  
Optical Systems ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Spectral Window ◽  
Optical Limiters

AbstractSystematic studies of the nonlinear optical properties of metallo-organic materials have led to the development of promising new phthalocyanine materials for optical limiting. Several heavy metal substituted phthalocyanines exhibit a strong nonlinear absorption that is useful for optical limiters in the visible. In fast optical systems, other mechanisms, such as the thermal refraction, contribute to the limiting. The spectral window for limiting can by modified by altering the molecular structure.

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