Ken-ichi Watabe

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High-contrast coherent population trapping signals were observed on the Cs D1 line by use of a bichromatic linear polarized light (lin‖lin field). A maximum absorption contrast of about 10% was obtained. This was nearly twice as high as that measured with the standard configuration of bichromatic circularly polarized light (σ-σ field). The results are(More)
The frequency stability of an atomic fountain clock was significantly improved by employing an ultra-stable local oscillator and increasing the number of atoms detected after the Ramsey interrogation, resulting in a measured Allan deviation of 8.3 × 10(-14)τ(-1/2)). A cryogenic sapphire oscillator using an ultra-low-vibration pulse-tube cryocooler and(More)
We describe the recent progress in our cesium atomic fountains at National Metrology Institute of Japan (NMIJ). We have developed three atomic fountains: NMIJ-F1, NMIJ-F2, and a truncated atomic beam fountain. NMIJ-F1 has been the primary frequency standard with uncertainty of 4×10 -15 since 2004. Especially in the last 4 years, we have reported the data to(More)
This paper presents a complete monolithic 500V, 1A three phase motor driver. The single chip is composed of n-ch. lateral IGBTs, HV-diodes, 24V CMOS and HV-NMOS structures fabricated on an SOI (Silicon On Insulator) substrate using trench isolation techniques. The chip is assembled into a newly designed surface mount SOP (small outline package) with a body(More)
Technical issues are investigated for a precise frequency transfer system using two-way signals by wavelength division multiplexing (WDM) in a single fiber. Bi-directional optical amplifiers are necessary to make the distance longer. Frequency stability is shown in the tandem optical amplifier link where the amplified spontaneous emission (ASE) noises are(More)
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