The hybrid metal subwavelength structure which takes advantage of two different noble metals in their structures have become increasingly important as they can combine plasmonic dipole peaks associated with palladium (Pd) as well as silver (Ag), and thereby create additional plasmonic peaks. The additional peaks can provide a higher degree of control over the tunability of nanorods resonance and can potentially be beneficial in strong optical trapping application. With that in mind, in this paper, we introduce a near infrared plasmonic resonance (NIR) optical trapping based on hybrid nanorod pair array structure consisting of Pd and Ag metallic nanorods. The near infrared surface plasmons can be excited by using the hybrid metals subwavelength structure under the NIR wavelength. When the surface Plasmon (SP) wave impinges on the surfaces of hybrid metal injection molding (MIM), the two surface plasmon polaritons (SPPs) can be excited and propagate along the Pd and Ag surfaces. The constructive interference of these surface plasmons launched by the subwavelength hybrid structure can form an intense light field. The relationship between the incident wavelength, the distance of the Pd and Ag nanorod, and the forming intense light field are discussed in detail in order to design the optimal performance optical trapping structure for practical application. Based on Maxwell stress tensor method and numerical simulations, the maximum of optical force was calculated to be about 6.6 nN with input power 50mW. The proposed nanostructure has great potential to trap nanoparticles and may be easily integrated into a small chip because of its simple structure for lab-on-a-chip applications.
Supplementary files can be found here, including Additional Methods and Data.