Akito Kuramata

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A broad-band semiconductor optical amplifier (SOA) that achieves both a high chip saturation output power and a low chip noise figure (NF) was developed by using a thin multiquantum well with low internal loss. The SOA exhibited a high chip saturation output power of >+19.6 dBm and a low chip NF of <4.5 dB over a 3-dB gain bandwidth of 120 nm (1450-1570(More)
A semiconductor optical amplifier having a gain of >20 dB, noise figure of >7 dB, and 3-dB saturation output power of >19 dBm, over the record widest bandwidth of 120 nm among all kinds of optical amplifiers, and also having a penalty-free output power of 23 dBm, the record highest among all the semiconductor optical amplifiers, was realized by using(More)
A semiconductor optical amplifier (SOA) having a gain of >25 dB, noise figure of <5 dB, and 3-dB saturation output power of >19 dBm, over the record widest bandwidth of 90 nm among all kinds of optical amplifiers, and also having a penalty-free output power of 23 dBm, the record highest among all the SOAs, was realized by using quantum dots.
Since successful lasing has been reported for wurtzite (WZ) GaN and related materials, researchers are now interested in exploring the possibility of reducing the threshold current density (Jth). In this paper, we focus on this point by calculating the optical gain. We discuss the reduction in Jth on the c-plane, and we investigate the anisotropic strain(More)
InP-based Mach-Zehnder modulators with capacitively loaded traveling-wave electrodes (CL-TWEs), which have segmented structures along the optical waveguides, are presented. Devices with various structural parameters for gap length (the length between adjacent segmented phase modulators) and total active length were fabricated and investigated both optically(More)
As a next generation wide bandgap semiconductor for power electronics, &#x03B2;-Ga<sub>2</sub>O<sub>3</sub> (Ga<sub>2</sub>O<sub>3</sub>) has shown a lot of potential in recent studies. It has been reported to have high Baliga's Figure of Merit (BFoM), a figure of merit for power devices, next only to diamond among wide bandgap semiconductor materials [1].(More)
Zhi Guo, Amit Verma, Xufei Wu, Fangyuan Sun, Austin Hickman, Takekazu Masui, Akito Kuramata, Masataka Higashiwaki, Debdeep Jena, and Tengfei Luo Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA Department of Electrical(More)
Depletion-mode field-plated Ga<sub>2</sub>O<sub>3</sub> metal-oxide-semiconductor field-effect transistors were demonstrated for the first time. Substantial enhancement in breakdown voltage was achieved with a gate-connected field plate. The device channels, formed by selective-area Si ion implantation doping of an undoped Ga<sub>2</sub>O<sub>3</sub>(More)
Wide-wavelength-band operation of InP-based Mach-Zehnder modulators is investigated. From the measured dependences of the half-wavelength voltage on operating wavelength and applied-bias voltage, it is shown that wide-wavelength operation with a constant driving voltage can be realized by adjusting the bias voltage for each operating wavelength.(More)