Donghyun Lee

Design and Simulation of Fabrication-Error-Tolerant Triplexer Based on Cascaded Mach–Zehnder Inteferometers

A planar lightwave circuit triplexer with good fabrication-error-tolerance is proposed and its characteristics are analyzed through simulations. To separate 1310 nm and 1480-to 1560-nm channels properly, the path length difference of two-stage Mach-Zehnder interferometers (MZIs) is set to be a multiple and half of the upstream wavelength (1310 nm) and the balance of the employed 3-dB directional couplers is optimized in 1480-to 1560-nm band. Two downstream channels (1490-and 1550-nm channels) are further separated using additional two-stage MZIs. A three-dimensional beam propagation method and transfer matrix method analysis predicts that the channel crosstalk at 1310-nm port would be less than -35 dB from 1290 to 1330 nm. The crosstalk could be less than -22 dB at two downstream channels and less than -55 dB at the upstream channel when the waveguide width error is as much as 0.2 mum.

Widely Tunable Coupled-Ring-Reflector Filter Based on Planar Polymer Waveguide

A widely tunable coupled-ring-reflector filter based on compact polymer waveguide is fabricated and the characteristics are measured. The ring radii of two rings are slightly different, which are 150 and 156 m, to achieve wide tuning of 43 nm using a low heating current as small as 37 mA.

High performance piezoelectric MEMS energy harvester based on D33 mode of PZT thin film on buffer-layer with PBTIO3 inter-layer

In this paper, a MEMS energy harvester was investigated to scavenge power from ambient vibration source. It was designed to convert low level vibration to electrical power via the piezoelectric effect. The proposed energy harvester was fabricated by patterning Pt electrodes into inter-digital geometry on top of the sol-gel-spin coated Pb(Zr,Ti)O<inf>3</inf> thin film for d33 mode on silicon cantilever with proof mass. In order to obtain well grown PZT thin film, PbTiO3 seed-layer was newly applied as an inter-layer between PZT and ZrO<inf>2</inf> layer. The fabricated energy harvester generated 1.1uW of electrical power to 2.2MΩ of load with 4.4V<inf>peak-to-peak</inf> from a vibration of 0.39g acceleration at it resonant frequency of 528Hz. The corresponding power density was 2.8mW·cm^−3·g⁻¹.

Widely Tunable Double-Ring-Resonator Add/Drop Filter Using High-Index-Contrast Polymer Waveguide

A widely tunable add/drop filter composed of double ring resonators is implemented with high- index-contrast polymer waveguide. The drop response gets enhanced by more than 25% at the wavelength where both rings resonate, which makes this device suitable for wavelength selective component in realizing widely tunable hybrid laser diode.

Piezoelectric Properties of 0.98(Na 0.5 K 0.5 )NbO 3 -0.02Li(Sb 0.17 Ta 0.83 )O 3 +0.01wt%ZnO Ceramics with a Sintering Temperature

We studied sintering temperature to enhance the piezoelectric properties of +0.01wt%ZnO (hereafter NKN-LST+ZnO) lead free piezoelectric ceramics. The synthesis and sintering method were the conventional solid state reaction method and sintering was executed at . We found that NKN-LST+ZnO ceramics at optimal sintering temperature showed the improved piezoelectric properties at the optimal sintering temperature. The NKN-LST+ZnO ceramics show good performance with piezoelectric constant

Design and Fabrication of Widely Tunable Polymer Waveguide Coupled-Ring Reflector

A widely tunable coupled-ring reflector (CRR) based on planar polymer waveguide is fabricated and the characteristics are measured. The ring radii of the coupled rings are slightly different to achieve wide tuning of a few tens nm using a low current level as small as a few tens mA.

Fabrication-Error-Tolerant Triplexer based on Planar Lightwave Circuit

A fabrication-error-tolerant planar lightwave circuit triplexer is proposed and analyzed. The triplexer is composed of cascaded Mach-Zehnder interferometer structures with carefully designed path length difference and robust 3-dB couplers. The channel crosstalk at upstream channel is maintained to be less than -50 dB and those at downstream channels less than -20 dB when the waveguide width error is as much as plusmn0.2 mum.

Design and Analysis of Mach-Zehnder-Interferometer-Based Silica Planar Lightwave Circuit Triplexer

A triplexer based on a silica planar lightwave circuit Mach-Zehnder nterferometer(MZI) is proposed and its characteristics are analyzed through simulations. To separate 1310 nm band and band properly, the path length difference of an MZI is set to be the multiple and half of the wavelength 1310 nm and the balance of the directional coupler is optimized in the band. The same MZI is additionally cascaded to provide good crosstalk characteristics. The 1490 nm band and 1550 nm band are further separated using additional two stage MZI`s. A three-dimensional BPM and transfer matrix method analysis predicts the low crosstalk characteristics and the fabrication-error-tolerance of the proposed triplexer.