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Your search keyword '"Y. Nakasha"' showing total 4 results
Start Over Author "Y. Nakasha" Publication Year Range Last 10 years
4 results on '"Y. Nakasha"'

1. Surface-oxide-controlled InGaAs/InAlAs inverted-type metal-oxide-semiconductor high electron mobility transistors for sub-THz high-power amplifiers

Author

S. Ozaki, Y. Kumazaki, N. Okamoto, Y. Nakasha, N. Hara, and T. Ohki

Subjects
General Engineering, General Physics and Astronomy
Abstract

Herein, we successfully improved the maximum oscillation frequency and maximum stable gain (MSG) across a wide bias range of surface-oxide-controlled (SOC) InGaAs/InAlAs inverted-type metal-oxide-semiconductor high-electron-mobility transistors (inverted MOS-HEMTs) by reducing the gate leakage current and drain conductance (g d). H2O vapor treatment selectively decreased the narrow band gap indium oxide at the surface of the In-based epitaxial layer via the SOC process before the gate oxide deposition. Furthermore, the calculation of band profiles indicated that the gd reduction was possibly attributed to the suppression of impact ionization in the InGaAs channel by inverted MOS-HEMTs. Consequently, SOC-inverted MOS-HEMTs demonstrated a high MSG of >12 dB at 100 GHz across a wide bias range.

Published
2023
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4. Cascaded AMZ triplets: a class of demultiplexers having a monitor and control scheme enabling dense WDM on Si nano-waveguide PICs with ultralow crosstalk and high spectral efficiency.

Author

Akiyama T, Oda S, Nakasha Y, Hayakawa A, Tanaka S, Tanaka Y, and Hoshida T

Abstract

We propose a class of wavelength-division multiplexing (WDM) demultiplexers having a novel monitor and control scheme enabling dense WDM on Si nano-waveguide (NW) photonic integrated circuits (PICs), which had been impossible due to the critically small fabrication tolerance of the extremely miniaturized waveguide structure. With a computer simulation, we show our proposed demultiplexers enable crosstalk in the range of -50 to -40 dB, flat-topped spectrum for high spectral efficiency, and channel counts as large as 64. We have experimentally evaluated the validity of this type of demultiplexers by using a 4-ch WDM demultiplexer, which has shown total crosstalk of < -49 dB as a result of fully automatic control of heaters. This technology is expected to drastically shrink the size of dense WDM transceivers, paving the way for future sustainable scalability in the capacity of optical transceiver systems.

Published
2021
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