Byeong-Hyeon Lee

Compact polarizing beam splitter based on a metal-insulator-metal inserted into multimode interference coupler

We propose and analyze a compact polarizing beam splitter (PBS) based on a metal-insulator-metal (MIM) structure inserted into a multimode interference coupler (MMI). Owing to the MIM structure, the TE polarized state is reflected by the cut-off condition while the TM polarized state is transmitted by the surface plasmon polariton, and the two polarized states can thus be separated. In this paper, the dependence of the reflected TE and transmitted TM field intensities on the MIM length and the gap thickness has been studied systematically. The proposed PBS structure, with a total size of 4 × 0.7 × 44 µm(3) is designed with MIM length, gap thickness, and metal thickness of 0.6 µm, 0.5 µm, and 0.05 µm, respectively. In the designed PBS, the transmittance for the TM polarized light, reflectance for the TE polarized light, extinction ratio, and insertion losses of the TE and TM modes are obtained using a 3D finite-difference time-domain method to be 0.9, 0.88, 12.55 dB, and 1.1 dB and 0.9 dB, respectively. The designed PBS has a much shorter length, 44 µm, compared to previous PBS devices.

Compact polarization rotator based on slotted optical waveguide with buffer layer using surface plasmon polariton

A novel polarization rotator with asymmetric optical waveguide based on plasmonics is proposed and analyzed for the first time. The polarization rotator using skewing effects at the slotted optical waveguide (SOW) with metal film was designed by 3D-FDTD method. A metal film on the waveguide acts to rapidly rotate the optical polarization, because the plasmonic characteristics of a metal film can induce the slow group velocity through the metal-clad optical waveguide. Here, the optical waveguide with a buffer layer is proposed to reduce the propagation loss. The polarization rotator length of 6 μm is among the shortest reported in the waveguide-type polarization rotators. The polarization conversion efficiency of 98.93 % is observed near 1550 nm along with a propagation loss of -0.43 dB. The proposed structure is smaller than previous polarization rotator with asymmetric optical waveguide and is more effective to control polarizations using by plasmonic effects.

Design of high sensitive surface plasmon resonance sensor with metallic nano-structure

In this paper, we have designed and optimized the metallic nano-structures on a conventional surface plasmon resonance (SPR) sensor which induce the localized surface plasmon resonance for an improved sensitivity. Designed SPR sensor was simulated with 3D Finite-difference time-domain method. The sensitivity is maximized to 130.9 degree/RIU when the thickness of film layer TF is 30 nm while that of a conventional SPR sensor is less than 99.6 degree/RIU, and the reflectivity is minimized when TF is 25 nm. The most appropriated diameter of particles is about 35 nm for high sensitivity.

Significantly enhanced sensitivity of surface plasmon resonance sensor with self-assembled metallic nanoparticles

Abstract. A surface plasmon resonance (SPR) sensor hybridized with self-assembled metallic nanoparticles is proposed and experimentally demonstrated. The measured sensitivity of the proposed SPR sensor is 110.77  deg/RIU, while that of a conventional SPR sensor is 84.75  deg/RIU. The enhanced sensitivity is attributed to the strong localized surface plasmons and the increased surface interaction area by the nanoparticles. Angle variation measurement, which is an easy detection method using bulk optics, is possible with this structure because a supplementary metallic thin film layer on the nanoparticles leads to utilization of the sensitive variation of the strong localized field by the change of the refractive index. Furthermore, the proposed structure can be fabricated with a very simple three-step nonlithographic process.

Analysis of hybridized surface plasmon resonance sensor with metallic nanoparticles for high sensitivity

In this paper, we propose a surface plasmon resonance (SPR) sensor with metallic nano-particles, which is based on the Kretschmann configuration for reflective-type measurement with enhanced sensitivity. The proposed structure is analyzed and compared with a conventional Kretschmann configuration by using 3D finite-difference time-domain method. The proposed structure is composed of semi-spherical nano-particles and a thin cladding layer. The evanescent field on the metallic structure is enhanced by the factor of 2.7, where the diameter of nano-particles, fill factor, and thickness of cladding film layer TF are 30 nm, 50 %, and 40 nm, respectively. On the other hand, the enhancement of the evanescent field in the conventional SPR sensor is 1.7 for the same TF. Because of the enhanced evanescent field, the sensitivity of our proposed sensor is maximized to 137.1 degree/RIU while that of a conventional SPR sensor is 99.6 degree/RIU.

Integrated surface plasmon resonance resonator using silicon on insulator

We introduce an ultra-sensitive integrated photonic sensor structure using silicon on insulator based triangular resonator, in which a surface plasmon resonance (SPR) gold film is applied on a total internal reflection mirror. We have analyzed and optimized the triangular resonator sensor structure with an extremely small SPR mirror sensing area. Due to the large phase shift in the SPR mirror, a significantly enhanced sensitivity of 800 nm/RIU (refractive index unit) and the maximum peak shift of half free spectral range have been obtained at the SPR angle of 22.65° with Au thickness of 35 nm for the change of the refractive index Δn = 1x10-3.

Design and fabrication of nano-plasmonics based high sensitivity sensor

We have designed and fabricated surface plasmon resonance (SPR) sensor with metallic nano-structure to improve sensitivity. We have fabricated the metallic nano particles with rapid thermal annealing process to realize the proposed nano-plasmonics SPR sensor. In experiments, we confirmed the sensitivity of the proposed nano-plasmonics SPR sensor is 93.75 degree/RIU while that of conventional SPR sensor is 84.76 degree/RIU.

Analysis of total reflection mirror based on horizontal slot waveguide

Recently, the bending efficiency of vertical slot waveguide with different structure has been analyzed. However, the interface roughness of the waveguide which have high E-field intensity induces to high scattering loss. In addition, a vertical slot fabrication involves in a very narrow region etching which can cause large roughness in the vertical interfaces. In order to reduce the propagation loss and facilitate the fabrication process, horizontal slot waveguides have been proposed and fabricated, recently. In this paper, we have designed and analyzed total internal reflection (TIR) mirror for using a resonator based on horizontal slot waveguide. Our proposed structure is consisted horizontal slot waveguide of rib type to enlarge contact region with TIR mirror. To analyze Goos-Hanchen shift, we have theoretically calculated length of evanescent field at TIR mirror using 3D-FDTD method. The presented TIR mirror loss analysis can be applied to enhance the efficiency of horizontal slot waveguide resonator which can potentially be used in many silicon based optoelectronic devices.

Analysis of 1D-like photonic crystal microcavity sensor using surface plasmon resonance effect

In this paper, we have theoretically analyzed and designed a 1D PhC microcavity sensor with SPR based on the total internal reflection mirror using analytic calculation and FDTD methods. The proposed structure has many advantages. One of that is a high sensitivity using SPR characteristics. Another is a high Q-factor of the characteristics in the PhC microcavity structure. The incident light has double resonance characteristics, because the filtered light by PhC structure is met the thin metal film for SPR effect. We have also observed the change of resonance characteristics according to the variation of effective index on the metal film.

The surface plasmon resonance sensor with the metallic nanostructure for biosensing

In this paper, we have demonstrated a metallic nano-structured SPR sensor for an improvement of biosensing sensitivity using a metallic nano-structure. Permittivity of metal is calculated with Drude model for analysis. The sensitivity of SPR sensor with metallic nano-structure is 65 degree/RIU, and that of conventional SPR configuration is 54.8 degree/RIU. We have fabricated the random metallic nano-structures on the metallic thin film using the RIE etching process. Moreover, we have analyzed the structure using the finite-difference time-domain method for the exact characteristic.