Hitoshi Kawaguchi

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Five basic tastes (bitter, sweet, umami, salty, and sour) are detected in the four taste areas where taste buds reside. Although molecular mechanisms for detecting bitter, sweet, and umami have been well clarified, those for sour and salty remain poorly understood. Several channels including acid-sensing ion channels have been proposed as candidate sour(More)
A novel optical buffer memory with shift register function is proposed. The buffer consists of a two-dimensional array of polarization-bistable vertical-cavity surface-emitting lasers (VCSELs), in which the bit state of the optical signal, " 0 " or " 1 " is stored as a lasing linear polarization state of 0 or 90°. Two-bit optical buffering is experimentally(More)
High-speed all-optical switching is demonstrated by four-wave mixing (FWM) of picosecond pulses using semiconductor optical amplifiers (SOA). A light source for measurement and switching in the 1.5 µm region is produced using a normal group velocity dispersion fiber and optical parametric oscillator. The output supercontinuum (SC) optical pulses, with a(More)
We report an electrically pumped hybrid cavity AlGaInAs-silicon long-wavelength VCSEL using a high contrast grating (HCG) reflector on a silicon-on-insulator (SOI) substrate. The VCSEL operates at silicon transparent wavelengths ~1.57 μm with >1 mW CW power outcoupled from the semiconductor DBR, and single-mode operation up to 65 °C. The thermal resistance(More)
We report on a study of polarization properties of asymmetric, multimode vertical-cavity surface-emitting lasers (VCSEL) subjected to electrical RF modulation. When subjected to RF modulation, complex frequency-dependent polarization properties, especially near the polarization switching point are revealed. We propose a scheme of rapidly switching the two(More)
—Ultrafast all-optical memory operation was experimentally demonstrated using a 980-nm polarization-bistable vertical-cavity surface-emitting laser. 1-bit data signals were arbitrarily sampled and memorized from a 2 6-1 pseudorandom bit sequence return-to-zero signal at 20 Gb/s and a 6-bit non-return-to-zero signal at 40 Gb/s by AND gate and memory(More)