• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.223-227
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• 2002

Polymeric multi-mode optical waveguides were fabricated for parallel optical interconnection. Waveguide structures were molded by a Ni mold master using a hot embossing technique. The Ni mold master was manufactured by LIGA process. Multimode optical waveguides with a 48$\times$47 ${\mu}{\textrm}{m}$$^2$cross-section were produced by a simple two-step process. The propagation losses of the multimode waveguide measured at 0.85 ${\mu}{\textrm}{m}$ and 1.3 ${\mu}{\textrm}{m}$ wavelengths were 0.38 dB/cm and 0.66 dB/cm, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.145-150
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• 2023

Non-uniform optical taper waveguides have been widely used as devices for high-efficiency mode coupling, as they are integrated with single-mode optical fibers or photonic crystal waveguides. In this paper, we present a new platform for chemical sensing and bio-sensing using optical taper waveguides with these characteristics. The principle of operation is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multi-mode interference coupler (MMIC). First, the curvature characteristics of taper sections of DC and MMIC is explained, and the design specifications of optimized taper waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the change in refractive index of sensing analyte is numerically analyzed. Numerical results show that as the length of couplers increases, the effective index per change in refractive index unit (RIU) of analyte increases, and that sensitivity can be tuned using taper DC and MMIC design techniques.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.669-673
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• 2003

We fabricated a buried-ridge waveguide laser diode (B-RWG LD) which has more advantages for obtaining lateral single mode operation on the same ridge width and for the planarization of the device surface, compared to the conventional RWG LD. In this LD, the difference of the lateral effective refractive index can be controlled by the thickness of the InGaAsP layer which is grown on the active and the p-InP layers. The InGaAsP multiple quantum well was grown on a n-InP substrate by the CBE. The buried ridge structure was formed by selective wet etchings, followed by liquid phase epitaxy methods. The fabricated LD with the ridge width of 7 ${\mu}{\textrm}{m}$ showed a linear increase of the optical power up to 20 ㎽ without any kinks and a saturated output power of more than 80 ㎽. By measuring the far field pattern, we demonstrate that LDs with the ridge widths of 5 ${\mu}{\textrm}{m}$ and 7 ${\mu}{\textrm}{m}$ were operated in a lateral single mode up to 2.7I$_{th}$ and 2.4I$_{th}$, respectively.ely.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.50-55
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• 2007

Using the Selective Area Growth (SAG) technology of Metal Organic Chemical Vapor Deposition (MOCVD), we successfully integrated an active device and passive devices on the same substrate. In other words, we integrated a Semiconductor Optical Amplifier (SOA) as an active device and an S-bend waveguide and a Multi Mode Interference (MMI) waveguide as passive devices. The SOA is successfully integrated with passive devices on the same substrate. The Cross-Gain Modulation (XGM) characteristic of the integrated SOA and the loss of an MMI and an S-bend waveguide were measured. Measured XGM characteristics of the SOA showed an extinction ratio of 8.82 dB. The total loss of the MMI and S-bend waveguide was 18 dB.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.175-183
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• 2024

Research into optical signal processing using photonic integrated circuits (PICs) has been actively pursued in various fields, including optical communication, optical sensors, and quantum optics. Among the materials used in PIC fabrication, polymers have attracted significant interest due to their unique characteristics. To fabricate polymer-based PICs, establishing an accurate manufacturing process for the cross-sectional structure of an optical waveguide is crucial. For stable device performance and high yield in mass production, a process with high reproducibility and a wide tolerance for variation is necessary. This study proposes an efficient method for fabricating polymer optical-waveguide devices by introducing the atomic layer deposition (ALD) process. Compared to conventional photoresist or metal-film deposition methods, the ALD process enables more precise fabrication of the optical waveguide's core structure. Polyimide optical waveguides with a core size of 1.8 × 1.6 ㎛² are fabricated using the ALD process, and their propagation losses are measured. Additionally, a multimode interference (MMI) optical-waveguide power-splitter device is fabricated and characterized. Throughout the fabrication, no cracking issues are observed in the etching-mask layer, the vertical profiles of the waveguide patterns are excellent, and the propagation loss is below 1.5 dB/cm. These results confirm that the ALD process is a suitable method for the mass production of high-quality polymer photonic devices.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.19-22
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• 2017

In this study, wavelength-free $1{\times}N$ optical splitter using a tapered polymer waveguide was studied to realize the transmission network of high-speed information communication network. Based on the evaluation of mode converting characteristics of splitter having two tapered multi-mode interference structures, an optimized structure of the $1{\times}N$ splitter was proposed for wide-range of input wavelength. 2D-BPM analysis $1{\times}8$ model showed that insertion loss of the proposed splitter is less than 10 dB for wavelength of input source from 1260 nm to 1650 nm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.6
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• pp.1587-1595
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• 1996

We obtained the predicted and measured results for the reflection coefficient and radiation pattern of Ka-band (20- GHz) corrugated horn, which is usually used for feeder of reflector antenna for satellite communication, using suface impedance condition. In order to predict the reture losses of corrugated horn, we analyzed propagation constant of hybrid mode in the corrugated waveguide and then obtained the total reflection coefficient using the circuti theory of multi-step transformer. We also got the radiation pattern of corrugated horn with small flare angle, considering the phase deviation and integrate transverse field on aperture. A test model of corrugated horn antenna for Ka-band designed using theory and program displayed performance and the results agree with the theoretical prediction.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.142-145
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• 2003

The nonreciprocal phase shift characteristics of infinite slab optical waveguides with magneto-optic materials in the cladding layer was calculated at 1.55 ${\mu}{\textrm}{m}$ for optical isolators. The infinite slab waveguide structures considered in this paper were as follows. rho magneto-optic materials used as a cladding layer were Ce:YIG and LNB(LuNdBi)$_3$(FeAl)$_{5}$)$_{12}$,). Their specific Faraday rotations Θ$_{F}$ are 4500$^{\circ}$/cm, 500$^{\circ}$/cm at wavelength 1.55 ${\mu}{\textrm}{m}$ respectively. The guiding layer with multi-quantum well structure was used, and it consists of 1.3Q and InGaAs. In order to investigate the effect of evanescent field penetrating the cadding, layer, guiding mode characteristics were calculated for the cases when the substrate is InP and air. We calculated the minimum lengths of 90$^{\circ}$ nonreciprocal phase shifters and their optimum guiding layer thicknesses in various optical waveguide structures.res.s.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.667-678
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• 2002

In this paper, a new radiating structure with a multi-layered two-dimensional metallic disk array was proposed for shaping the flat-topped element pattern. It is an infinite periodic planar array structure with metallic disks finitely stacked above the radiating circular waveguide apertures. The theoretical analysis was in detail performed using rigid full-wave analysis, and was based on modal representations for the fields in the partial regions of the array structure and for the currents on the metallic disks. The final system of linear algebraic equations was derived using the orthogonal property of vector wave functions, mode-matching method, boundary conditions and Galerkin's method, and also their unknown modal coefficients needed for calculation of the array characteristics were determined by Gauss elimination method. The application of the algorithm was demonstrated in an array design for shaping the flat-topped element patterns of $\pm$20$^{\circ}$ beam width in Ka-band. The optimal design parameters normalized by a wavelength for general applications are presented, which are obtained through optimization process on the basis of simulation and design experience. A Ka-band experimental breadboard with symmetric nineteen elements was fabricated to compare simulation results with experimental results. The metallic disks array structure stacked above the radiating circular waveguide apertures was realized using ion-beam deposition method on thin polymer films. It was shown that the calculated and measured element patterns of the breadboard were in very close agreement within the beam scanning range. The result analysis for side lobe and grating lobe was done, and also a blindness phenomenon was discussed, which may cause by multi-layered metallic disk structure at the broadside. Input VSWR of the breadboard was less than 1.14, and its gains measured at 29.0 GHz. 29.5 GHz and 30 GHz were 10.2 dB, 10.0 dB and 10.7 dB, respectively. The experimental and simulation results showed that the proposed multi-layered metallic disk array structure could shape the efficient flat-topped element pattern.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.153-160
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• 2010

We optimized the Si(substrate)/$SiO_2$(cladding)/$Si_3N_4$(antiresonant cladding)/$SiO_2$(core)/air multi-layers rib-optical waveguides of antiresonant reflecting optical waveguide (ARROW) for integrated optical biosensor structure utilizing beam propagation method (BPM). Thickness of anti-resonant cladding was derived to minimize the propagation loss and leaky field mode deeply related with evanescent mode was theoretically derived. Depth, width, refractive index and cladding thickness of anti-resonant cladding were numerically calculated into 2.3${\mu}m$, 5${\mu}m$, 1.488, and 0.11${\mu}m$ respectively to minimize propagation loss using the BPM simulation tool. Finally one- and two-dimensional propagation characteristics of ARROW was confirmed.