Breath sensing is an effective tool for health monitoring. Previously, high-mesa waveguide structures have been proposed by our group for realizing a compact breath-sensing photonic circuit. By using the doped as the waveguide core, 50% concentration has been detected. One issue of preventing parts per million (ppm)-order detection is the low portion of evanescent light (=2.2) in the doped waveguides. In order to realize low propagation loss and high simultaneously, thin silicon (Si) waveguides with a as high as 37.6% have been proposed and fabricated in this work. A thermal oxidation technique was applied to further reduce , so that was decreased from 1.45 to 0.84 and 0.29 to 0.2 dB/cm for the 0.5 and 3-µm-wide waveguide, respectively. According to our analysis, the significantly decreased is attributed to recovering the damaged Si core and smoothing the waveguide sidewalls. The high and effective loss reduction show a promising potential of applying Si high-mesa waveguides to realize ppm-order sensing.
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http://dx.doi.org/10.1364/AO.391604 | DOI Listing |
Breath sensing is an effective tool for health monitoring. Previously, high-mesa waveguide structures have been proposed by our group for realizing a compact breath-sensing photonic circuit. By using the doped as the waveguide core, 50% concentration has been detected.
View Article and Find Full Text PDFWe demonstrate a hitless wavelength-selective switch (WSS) based on InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) quadruple series-coupled microring resonators. The WSS is driven by the electric-field-induced change in refractive index in the FACQW core layer caused by the quantum-confined Stark effect (QCSE) for high-speed operation. The WSS with high-mesa waveguides is fabricated on a molecular beam epitaxy-grown wafer by dry etching.
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July 2013
Graduate School of Engineering, Yokohama National University, Yokohama, Kanagawa 240-8501, Japan.
Modulation characteristics of a novel InGaAs/InAlAs multiple quantum well (MQW) microring-enhanced Mach-Zehnder modulator (MRE-MZM) is investigated in detail and its low-voltage operation with high extinction ratio is demonstrated. The MZM has a single microring resonator in one arm and is driven by the change in electrorefractive index induced by the quantum-confined Stark effect in the MQW core layer. As the MQW, a multiple five-layer asymmetric coupled quantum well (FACQW) is used to obtain a large electrorefractive index change.
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December 2011
I-Eggs (Interdisciplinary Graduate School of Engineering Sciences), Kyushu University 6-1, Kasuga-koen, Kasuga, Fukuoka, 816-8580, Japan.
We demonstrate fast and low energy all optical flip-flop devices based on asymmetric active-multimode interferometer using high-mesa waveguide structure. The implemented devices showed high speed all-optical flip-flop operation with 25 ps long pulses. The rising and falling times of the output signal were 121 ps and 25 ps, respectively.
View Article and Find Full Text PDFJ Nanosci Nanotechnol
November 2006
Department of Information and Communications, Gwangju Institute of Science and Technology, Oryongdong Bukgu Gwangju 500-712, South Korea.
Low loss high mesa optical waveguides were fabricated on InGaAsP/InP heterostructures by utilizing inductively-coupled-plasma reactive ion etching (ICP-RIE) and electron beam lithography technique. The fabrication process was optimized by measuring sidewall roughness of deep-etched waveguides. Atomic force microscope loaded with carbon nanotude was used to obtain three-dimensional image of the etched sidewall of waveguides.
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