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We search for steady TeV γ-rays from 18 pulsars in the Fermi-LAT pulsar catalog using the Tibet air shower array. We observe 8 sources including the Crab against expected 0.41 sources at a significance of 2σ or more among the 18 pulsars. The chance probability from Poisson statistics is estimated to be 1.4×10-8.With the Crab excluded, it is estimated to be 1.8×10-7. These low chance probabilities...
Distribution of electric fields normal to the antenna plane in the depth direction was experimentally investigated by using mid-infrared circular antennas that were formed on Al2O3/SiO2/Si and SiO2/Al2O3/Si. The Al2O3 layer was deposited using an atomic layer deposition technique which allowed for layer thickness control with an accuracy of nanometers. The field distribution in the depth direction...
The electric field in the normal direction was experimentally investigated by using mid-infrared antennas that were formed on a thin Al2O3 layer/Si substrate. The Al2O3 layer could be as thin as a single nm-order employing the atomic layer deposition, and was varied from 2 nm to 50 nm. The field distribution was estimated by observing the reflectivity change. It was found that the electric field decreased...
We realized an ultimately advanced imaging system that comprises a hemi-spherically curved, back-illuminated CMOS image sensor (BIS) and integrated lens which doubles the sensitivity at the edge of the image circle and increases the sensitivity at the center of the image circle by a factor of 1.4 with one-fifth lower dark current (Jd) than that of a planar BIS. Because the lens field curvature aberration...
After growing a thin Al2O3 layer by atomic layer deposition on a Si substrate, slot antenna arrays were formed on it. Reflectivity spectra measured in the mid-infrared range showed characteristic aspects, presumably caused by the surface phonon polariton of a SiO2 layer naturally formed on the Si substrate. When the Al2O3 layer thickness was 6 nm, such spectral features disappeared. In this way, we...
Raman-amplified four-wave mixing in optical fibers with polarization mode dispersion was found to be suppressed or enhanced at dip positions, which was affected by the relative position between two signal wavelengths and the zero-dispersion wavelength.
Relative intensity noise of a quantum cascade laser under optical feedback was first evaluated. Noise smaller than that of a conventional laser diode was due to a small line enhancement factor and long cavity length.
Raman-amplified four-wave mixing in optical fibers with polarization mode dispersion was investigated. The negative Raman gain spectrum, its splitting after an excitation power increase, and the physical reasons for these are reported.
This paper proposes a novel spectrum sharing technique for an existing wireless local area network (LAN) system (primary user) based on IEEE 802.11a, and a new system (secondary user) equipped with the proposed spectrum sharing technique. Both systems are assumed to behave according to carrier sense multiple accesses with collision avoidance (CSMA/CA) protocol. An objective of spectrum sharing techniques...
The linewidth enhancement factor (alpha) of a quantum cascade laser near room-temperature and its current dependence were investigated. The alpha, probably affected by the detuning, was still smaller than that of conventional semiconductor laser diodes.
The linewidth enhancement factor of a 5.2-μm distributed-feedback quantum cascade laser above the threshold current caused by detuning from the gain peak was investigated. We clearly observed different values for the linewidth enhancement factor.
The linewidth enhancement factor of a 5.2-μm distributed-feedback quantum cascade laser above the threshold current caused by detuning from the gain peak was investigated. We clearly observed different values for the linewidth enhancement factor.
The linewidth enhancement factor of a 5.2-mum distributed-feedback quantum cascade laser above the threshold current caused by detuning from the gain peak was investigated. We clearly observed different values for the linewidth enhancement factor.
Nowadays, a rotary blood pump can be used as not only for a bridge to transplantation (BTT) but also for a bridge to recovery (BTR) and a destination therapy (DT). In such cases, evaluation of the recovery level of the native heart provides useful information to improve the clinical strategy and decide adequate timing for removing of the RBP. In contrast, the indices for cardiac function have been...
We have successfully developed a novel AlGaN/GaN FET with dual field-modulating-plates (FPs). The breakdown voltage is enhanced from 125 to 250 V by adding the second FP to the conventional FP structure. Benefiting from the first FP, no current collapse is observed simultaneously. Since the second FP effectively reduces feedback capacitance, this device provides a 3-dB higher gain along with increased...
Summary form only given. Vertical-cavity surface-emitting lasers (VCSELs) should play an important role in future optical data links. However, because polarization direction in conventional VCSELs is not determined, noise enhancement due to polarization switching by feedback light from optical fiber or other components becomes a serious problem. This paper presents for the first time, to our knowledge,...
Summary form only given. A laser cavity closed via the first-order diffracted light of an acousto-optic modulator is referred as a frequency-shifted feedback laser (FSFL). The laser exhibits outstanding features in its oscillation spectrum. We previously demonstrated the first oscillation of all-solid-state Nd:YVO/sub 4/ FSFL, and it was made clear that internal structure of the spectrum consists...
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