Min-Suk Kwon

We propose and investigate experimentally a micro-ring-resonator-based sensor with which we can measure both the concentration and temperature of glucose solution. It consists of two micro-ring resonators consecutively coupled to a bus waveguide by the overlap between them. The resonance wavelengths of the two resonators change similarly with the temperature but differently with the concentration. For that purpose, the core of just one micro-ring resonator is exposed directly to the solution. Us

Metal-insulator-silicon-insulator-metal (MISIM) waveguides are proposed and investigated theoretically. They are hybrid plasmonic waveguides, and light is highly confined to the insulator between the metal and silicon. As compared to previous ones, they are advantageous since they may be realized in a simple way by using current standard CMOS technology and their insulator is easily replaceable without affecting the metal and silicon. First, their structure and fabrication process are explained,

Horizontal slot waveguides based on graphene have been considered an attractive structure for optical waveguide modulators for transverse magnetic (TM) modes. Graphene is embedded in the slot region of a horizontal slot waveguide. If graphene were treated as an isotropic material and its dielectric constant were made close to zero by adjusting its Fermi level, the surface-normal electric field component of the fundamental TM mode of a horizontal slot waveguide might be highly enhanced in graphen

The feasibility of a polymer waveguide notch filter using a thermooptic long-period grating is demonstrated experimentally. It consists of a channel waveguide, a cladding surrounding the channel, and buffer layers sandwiching the cladding. Periodic heaters, placed on the filter surface, induce thermooptically a long-period grating. The attenuation of the filter is controlled by adjusting the power applied to the periodic heaters. The filter is made of thermocurable polymers by using conventional

We propose a new numerical method for exactly determining modes of a general multilayer waveguide. The proposed method has two features: simple implementation and fast calculation. Its implementation is simple since it is based on a complex root-finding algorithm reported recently. This algorithm is very intuitive and consists of the process of isolating each zero and that of determining the isolated zeros. To reduce calculation time, we propose and use an efficient scheme for evaluations of the

We demonstrate experimentally the feasibility of a polymer waveguide notch filter using a thermooptic long-period grating. This notch filter consists of a channel waveguide, a cladding surrounding the channel, and buffer layers sandwiching the cladding. Periodic heaters formed on the upper buffer layer induce a long-period grating thermooptically. Thus, they generate temporarily a resonance band of notch type in the transmission spectrum of the filter. Using thermocurable polymers, we have fabri

This paper proposes a tunable notch filter using a thermooptic long-period grating and investigates it theoretically. This notch filter is in the form of an integrated optical device and is based on a simple structure as compared with existing integrated optical notch filters. The thermooptic grating denotes a thermooptic index perturbation induced by periodic heaters. The attenuation of a resonance band in the transmission spectrum of the proposed notch filter can be controlled by adjusting the

We investigate, theoretically, a compact graphene-based electroabsorption modulator (EAM). The compactness of the EAM arises from an inverted-rib-type (IRT) silicon waveguide including a graphene-oxide-graphene stack. The EAM consists of input and output waveguides, which are conventional silicon strip waveguides, and the IRT waveguide efficiently connected to them through tapering regions. The stack is located in the region where the fundamental transverse electric mode of the IRT waveguide is

For the application of a long-period waveguide grating (LPWG) to a refractive index (RI) sensor, its RI sensitivity is experimentally investigated. The characteristics of the LPWG made of thermocurable polymers are observed when individual liquids with different RIs cover its cladding surface. They are sensitive to the RI of liquid. For the transverse-magnetic mode, the center wavelength of a resonance band increases by 77.7 nm as the RI of liquid increases from 1.0 to 1.47. The experimental res

We investigate experimentally metal-insulator-silicon-insulator-metal (MISIM) waveguides that are fabricated by using fully standard CMOS technology. They are hybrid plasmonic waveguides, and they have a feature that their insulator is replaceable with functional material. We explain a fabrication process for them and discuss fabrication results based on 8-inch silicon-on-insulator wafers. We measured the propagation characteristics of the MISIM waveguides that were actually fabricated to be con

Waveguide-coupled silicon ring or disk resonators have been used for optical signal processing and sensing. Large-scale integration of optical devices demands continuous reduction in their footprints, and ultimately they need to be replaced by silicon-based plasmonic resonators. However, few waveguide-coupled silicon-based plasmonic resonators have been realized until now. Moreover, fluid cannot interact effectively with them since their resonance modes are strongly confined in solid regions. To

This work reports a mid-infrared modulator based on a hybrid plasmonic waveguide with graphene on a grating in its slot region. The modulator utilizes a graphene plasmon for electro-optic tuning in a more practical and effective way than graphene-plasmon-based waveguide devices studied up to now. The hybrid plasmonic waveguide can be easily and efficiently integrated with input and output photonic waveguides. It supports a hybrid plasmonic waveguide mode and a graphene-plasmon-based waveguide mo

A polymer waveguide notch filter using two stacked thermooptic long-period gratings is proposed. It is a long-period waveguide grating whose transmission spectrum can be dynamically controlled. Thermooptic index perturbation, i.e., grating is temporarily induced by two groups of periodic heaters stacked vertically on the filter surface. The periods of the two groups are determined such that two different resonance bands are generated in the spectrum by the respective groups. Thus, the overall sp

This paper discusses a method of analyzing complex one-dimensional multilayer waveguides in a numerically stable way. When a multilayer waveguide contains a quite thick layer or a layer whose refractive index has a very large real or imaginary part, conventional analysis methods tend to fail to find out its modes. In order to solve such a problem, the discussed analysis method is based on modified transfer matrix equations. The method consists of three steps. At the first step, two types of modi