Kouichi Akahane

Learn More
We examine the timing dependence of nanophotonic devices based on optical excitation transfer via optical near-field interactions at the nanometer scale. We theoretically analyze the dynamic behavior of a two-input nanophotonic switch composed of three quantum dots based on a density matrix formalism while assuming arrival-time differences, or skew, between(More)
We theoretically and experimentally evaluated energy dissipation of nanophotonic devices based on energy transfer via near-field interactions and their interfaces with optical far-fields. The lower bound is about 10 4 times more energy-efficient than electronic devices. We also examined some fundamental differences between near-field-mediated optical energy(More)
An ultra-broadband photonic transport system has been developed to expand the usable wavelength bandwidth for optical communication. Simultaneous 3 x 10-Gbps error-free photonic transmissions are demonstrated in the 1-microm, C-, and L-wavebands by using the ultra-broadband photonic transport system over a 5.4-km-long holey fiber transmission line.
To open up a 1-microm waveband for photonic transport systems, we developed a hybrid and harmonically mode-locked semiconductor laser (MLL) that can transmit return-to-zero (RZ) optical signals at data rates on the order of gigabits per second. A single-mode hole-assisted fiber (HAF) was also developed for use as a 1-microm waveband signal transmission(More)
This paper describes high-speed optical modulation and detection devices for radio-over-fibre (RoF) systems which can distribute millimetre-wave signals over optical fibres with low-loss, and RoF-based high-performance imaging systems which can be used for foreign object debris in runways or railways. High-speed and high-sensitivity photo-detection would be(More)
Error-free Gbps-order high-speed optical data signal generation in a > 5.5-THz ultra-broad optical frequency bandwidth of the O-band was successfully demonstrated using a newly developed quantum dot electro-optic modulator integrated with a semiconductor optical amplifier.
An InGaAs quantum dot (QD) laser diode with 19-stacked QDs separated by 20 nm-thick GaAs spacers was fabricated using an ultrahigh-rate molecular beam epitaxial growth technique, and the laser characteristics were evaluated. A 19-stacked simple broad area QD laser diode was lased at the 1000 nm waveband. A net modal gain of 103 cm(-1) was obtained at 2.25(More)
We examine autonomous optical excitation transfer in mixtures of different-sized quantum dots networked via optical near-fields at the nanometer scale. We theoretically and experimentally demonstrate optical excitation transfer via the network of optical near-field interactions among quantum dots. The topology-dependent efficiency of excitation transfer is(More)