Dr. Vasanthan Devaraj Profile

Dr. Vasanthan Devaraj

at Pusan National Univ

SPIE Involvement:

Author

Publications (2)

Proceedings Article | 1 April 2020 Presentation

Experimentally tunable nanoparticle facet for a highly efficient plasmonic nanocavity device (Conference Presentation)

Vasanthan Devaraj, Jong-Min Lee, Samir Adhikari, Won-Geun Kim, Minjun Kim, Donghan Lee, Jin-Woo Oh

Proceedings Volume 11345, 113452E (2020) https://doi.org/10.1117/12.2555634

Read Abstract +

In realizing excellent plasmonic devices, a methodology based on flexibility and simplicity in fabrication, minimal sensitiveness to smaller nanoscale errors, larger dielectric layer thickness with superior device characteristics, and low-cost process is critically crucial for next-generation devices with multiple applications. One such attractive device is a plasmonic nanocavity, with numerous reports been already reported resulting in superior localized surface plasmon resonance (LSPR) and enhancement properties. The conventional spherical NP on a metallic mirror (NPOM) nanostructure’s plasmonic characteristics deteriorates with minor changes in dielectric layer thickness (t ≤ 6 nm). Alternatives like nanocube on mirror (NCOM), nanodisk on mirror (NDOM), provided better options towards LSPR tuning and near field enhancement. In recent times there are few reports based on faceted spherical NPOM design emerged. But however, the so far reported FNPOM nanostructures lacked the following: “facet width control, a clear SEM/TEM image of full geometry, and larger “t” with superior plasmonic characteristics”. In this work, for the first time, we report a clear FNPOM nanostructure with better control in facet fabrication using reactive thermal annealing (RTA) method. We used Ag NP on an Au mirror with SiO2 as a dielectric layer with different NP diameters of 50 nm, 70 nm and 100 nm with a precise facet width control (from 90% sphere to hemisphere). We employed a larger “t” ranging between 10 nm – 40 nm to display superior properties. From our dark field and LSPR mapping measurements, 70% of the sample are showed similar plasmonic characteristics from a 1 cm x 1 cm substrate. Our experiment results showed that it is possible to tune the LSPR resonance wavelength till 40 nm dielectric thickness reflecting it as a superior plasmonic nanocavity device. The reason behind this enhanced plasmonic characteristics is due to the introduction of facet in NPs and our three-dimensional finite difference time domain (3D FDTD) simulations results agreed well with experiment. For a final comparison, we checked our hemispherical shaped FNPOM versus NCOM design for NPs with diameter of 100 nm, where we find our FNPOM nanostructures showcased superior plasmonic properties.

Proceedings Article | 1 April 2020 Presentation

Bio-inspired M13 bacteriophage-based sub-nm actuator and its application towards the dynamic plasmonic device (Conference Presentation)

Vasanthan Devaraj, Jong-Min Lee, Hyuk Jeong, Won-Geun Kim, Jin-Woo Oh

Proceedings Volume 11361, 1136103 (2020) https://doi.org/10.1117/12.2555281

Read Abstract +

An highly efficient plasmonic/photonic devices requires precise nanoscale structural control which becomes critically essential for variety of application requirements. Advancements in lithography and deposition methods provided precise sub-nm structure with complex processing steps at high cost. Self-ssembly technique involving M13 bacteriophage (phage) provides us an alternative option with easy fabrication, high selectivity/sensitivity, and altogether with low-cost methodology. With such merits, we demonstrate two kinds of applications: A highly efficient dynamic actuator and dynamic plasmonic device. From our phage-based device it is possible to precisely control thickness in 0.2 nm step or in a broader range resulting in realization of highly efficient dynamic actuator device. Thickness modification is cross-checked using localized surface plasmon resonance (LSPR) measurements. On the other-side, variety of interesting complex plasmonic characteristics are extensively studied and an efficient plasmonic device is realized with precise sub-nm dynamic phage thickness modification. Critically, problems involving plasmonic devices which are extremely sensitive to sub-nm scale changes (≤ 1nm) can be solved utilizing dynamic M13 phage property. To strengthen dynamic plasmonic device characteristics, we introduce the metal-coated M13 phage-based nanostructures based on a simple and straight-forward drop-casting technique. Nanowires and island/NP structures are formed with precise control and reproducibilty. Nanowires with diameter range of ~ 6.6 nm – 150 nm and islands with diameter range of ~ 100 nm – 1200 nm are fabricated. By varying the humidity, highly efficient plasmonic characteristics are realized with the help of LSPR experiments. Our home-made built-in humidity chamber equipped with atomic force microscopy measurements revealed the sub-nm thickness variation of M13 phage, which agreed well with LSPR and optical simulation results. We hope our approach utilizing M13 bacteriophage as a supporting platform will open attractive applications in field of plasmonic devices, understanding complex plasmonic modes, sensors, actuators, energy devices and few other to name.

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years