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Tunable potential well for plasmonic trapping of metallic particles by bowtie nano-apertures

View Article: PubMed Central - PubMed

ABSTRACT

In this paper, the tunable optical trapping dependence on wavelength of incident beam is theoretically investigated based on numerical simulations. The Monte Carlo method is taken into account for exploring the trapping characteristics such as average deviation and number distribution histogram of nanoparticles. It is revealed that both the width and the depth of potential well for trapping particles can be flexibly adjusted by tuning the wavelength of the incident beam. In addition, incident wavelengths for the deepest potential well and for the strongest stiffness at bottom are separated. These phenomena are explained as the strong plasmon coupling between tweezers and metallic nanoparticles. In addition, required trapping fluence and particles’ distributions show distinctive properties through carefully modifying the incident wavelengths from 1280 nm to 1300 nm. Trapping with lowest laser fluence can be realized with1280 nm laser and trapping with highest precision can be realized with 1300 nm laser. This work will provide theoretical support for advancing the manipulation of metallic particles and related applications such as single-molecule fluorescence and surface enhanced Raman spectroscopy.

No MeSH data available.


Average displacement of the simulated particles.(▴ for data acquired by 1280 nm laser and ○ for data acquired by 1300 nm laser) and the number of the nanoparticle trapped in with a displacement to the center of tweezers below 15 nm (▾ for data acquired by 1280 nm laser and ⦁ for data acquired by 1300 nm laser). The particle size is 50 nm. The media temperature applied in the simulation is 300 kT.
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f4: Average displacement of the simulated particles.(▴ for data acquired by 1280 nm laser and ○ for data acquired by 1300 nm laser) and the number of the nanoparticle trapped in with a displacement to the center of tweezers below 15 nm (▾ for data acquired by 1280 nm laser and ⦁ for data acquired by 1300 nm laser). The particle size is 50 nm. The media temperature applied in the simulation is 300 kT.

Mentions: In Monte Carlo simulation, the average displacement and the number of the trapped particles depending on the fluence of the incident laser have been shown in Fig. 4. The wavelength of 1280 nm and 1300 nm, which corresponds to the incident wavelength for deepest potential well and for the strongest stiffness are applied, respectively. With increasing laser fluence, the average displacement of the nanoparticles irradiated by 1280 nm laser shows an evident decrease. When the laser flunece reaches to 3.2 × 108 W/m2, the average displacement can be concentrated below 10 nm. With continuously increasing laser fluence, however, the average displacement does not exhibit an evident decrease and is still larger than 4.5 nm. At the incident laser of 1300 nm, the average displacement can be controlled below10 nm only when the fluence is over 5 × 108 W/m2. When the fluence reaches to 8 × 108 W/m2 the average displacement can be controlled below 3 nm. When the laser fluence is lowered, it is the depth of the potential well that plays a key role in the trapping of nanoparticles. As a result, the stable trapping of nearly all the particles can be firstly realized with 1280 nm laser due to its deepest potential well. With increasing the laser fluence, both of the potential wells acquired by 1280 nm laser and 1300 nm laser are deep enough to assure a stable trapping. Correspondingly, it is the stiffness at the bottom of potential and width of the potential well that play key roles and nanoparticles are confined more efficiently by 1300 nm laser due tothe stronger stiffness than 1280 nm laser. Similar phenomenon can be also observed when considering the total number of the particles trapped with the displacement below 15 nm. In low fluence, compared with the 1300 nm laser, more particles are trapped with a displacement below in vicinity to the center of tweezers by 1280 nm laser. When the fluence is over 4 × 108 W/m2, however, the particle is more easily to be trapped in vicinity to the center of tweezers by the 1300 nm laser.


Tunable potential well for plasmonic trapping of metallic particles by bowtie nano-apertures
Average displacement of the simulated particles.(▴ for data acquired by 1280 nm laser and ○ for data acquired by 1300 nm laser) and the number of the nanoparticle trapped in with a displacement to the center of tweezers below 15 nm (▾ for data acquired by 1280 nm laser and ⦁ for data acquired by 1300 nm laser). The particle size is 50 nm. The media temperature applied in the simulation is 300 kT.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036050&req=5

f4: Average displacement of the simulated particles.(▴ for data acquired by 1280 nm laser and ○ for data acquired by 1300 nm laser) and the number of the nanoparticle trapped in with a displacement to the center of tweezers below 15 nm (▾ for data acquired by 1280 nm laser and ⦁ for data acquired by 1300 nm laser). The particle size is 50 nm. The media temperature applied in the simulation is 300 kT.
Mentions: In Monte Carlo simulation, the average displacement and the number of the trapped particles depending on the fluence of the incident laser have been shown in Fig. 4. The wavelength of 1280 nm and 1300 nm, which corresponds to the incident wavelength for deepest potential well and for the strongest stiffness are applied, respectively. With increasing laser fluence, the average displacement of the nanoparticles irradiated by 1280 nm laser shows an evident decrease. When the laser flunece reaches to 3.2 × 108 W/m2, the average displacement can be concentrated below 10 nm. With continuously increasing laser fluence, however, the average displacement does not exhibit an evident decrease and is still larger than 4.5 nm. At the incident laser of 1300 nm, the average displacement can be controlled below10 nm only when the fluence is over 5 × 108 W/m2. When the fluence reaches to 8 × 108 W/m2 the average displacement can be controlled below 3 nm. When the laser fluence is lowered, it is the depth of the potential well that plays a key role in the trapping of nanoparticles. As a result, the stable trapping of nearly all the particles can be firstly realized with 1280 nm laser due to its deepest potential well. With increasing the laser fluence, both of the potential wells acquired by 1280 nm laser and 1300 nm laser are deep enough to assure a stable trapping. Correspondingly, it is the stiffness at the bottom of potential and width of the potential well that play key roles and nanoparticles are confined more efficiently by 1300 nm laser due tothe stronger stiffness than 1280 nm laser. Similar phenomenon can be also observed when considering the total number of the particles trapped with the displacement below 15 nm. In low fluence, compared with the 1300 nm laser, more particles are trapped with a displacement below in vicinity to the center of tweezers by 1280 nm laser. When the fluence is over 4 × 108 W/m2, however, the particle is more easily to be trapped in vicinity to the center of tweezers by the 1300 nm laser.

View Article: PubMed Central - PubMed

ABSTRACT

In this paper, the tunable optical trapping dependence on wavelength of incident beam is theoretically investigated based on numerical simulations. The Monte Carlo method is taken into account for exploring the trapping characteristics such as average deviation and number distribution histogram of nanoparticles. It is revealed that both the width and the depth of potential well for trapping particles can be flexibly adjusted by tuning the wavelength of the incident beam. In addition, incident wavelengths for the deepest potential well and for the strongest stiffness at bottom are separated. These phenomena are explained as the strong plasmon coupling between tweezers and metallic nanoparticles. In addition, required trapping fluence and particles’ distributions show distinctive properties through carefully modifying the incident wavelengths from 1280 nm to 1300 nm. Trapping with lowest laser fluence can be realized with1280 nm laser and trapping with highest precision can be realized with 1300 nm laser. This work will provide theoretical support for advancing the manipulation of metallic particles and related applications such as single-molecule fluorescence and surface enhanced Raman spectroscopy.

No MeSH data available.