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A continuous beam of slow cesium atoms was produced from a thermal atomic beam by laser cooling. This beam was used as the source for the frequency standard. The Rabi-Ramsey spectrum was observed with the cold atomic beam. The Ramsey fringe of 62-Hz linewidth was obtained from a 21-cm-long microwave cavity. We found that the Rabi-Ramsey spectrum exhibited little dependence on the frequency of the pumping laser because of the long interaction time with the pumping light.

An optically pumped caesium-beam frequency standard (known as the KRISS-1) has been constructed at the Korea Research Institute of Standards and Science (KRISS) and the first measurements of long-term frequency stability have been made. Two methods were used to make the frequency standard immune to variations in the environmental temperature: an F = 4 → F' = 3 (σ + π)-polarized laser was used as a pumping source, and the difference between two sequential error signals was used as a feedback signal in the digital servo loop. A frequency stability of σy(τ) = 2.5 × 10-14 at τ = 105 s for a temperature variation of 4 °C was achieved with the KRISS-1.

We report a method to stabilize the frequency of a laser diode for a long time by means of four feedback loops including a digital feedback circuit. The laser frequency was locked at a saturated absorption peak of cesium atoms. In addition, by feeding back the frequency error signal to the temperature controller of the laser diode, the power as well as the frequency was stabilized at the same time. The power stability of 0.03% was obtained, which was 260 times better than that obtained without the feedback. The frequency stabilization continued for over 1 week and the fluctuation width was about ±0.5 MHz around the locking point.

A donor right hepatectomy (RH) is associated with a higher rate of morbidity than a left hepatectomy. Therefore, the precise morbidity should be known to improve the success of donor RH implementation. However, the rate of complication varies according to the individual definition of morbidity. This study prospectively analyzed the outcomes of 83 consecutive living donor RHs between January 2002 and July 2004 using a standardized classification of the severity of complications. The morbidity was classified using the modified Clavien system: grade I for minor complications; grade II for potentially life-threatening complications requiring pharmacological treatment; grade III for complications requiring invasive intervention; grade IV for complications causing organ dysfunction requiring intensive care unit management; and grade V complications resulting in the death of the patient. The donors were followed-up regularly for at least 12 months. No donor death or relaparotomy was noted. Overall, 65 out of 83 donors (78.3%) experienced postoperative complications: grades I, II, III, IV, and V complications in 64 (77.1%), 11 (13.3%), 1 (1.2%), 0, and 0 patients, respectively. The most common grade I complications were hyperbilirubinemia (n = 31) and pleural effusion (n = 31), and bile leakage in grade II (n = 7). The bilirubin and alanine aminotransferase levels were normal in 92.7% of donors at the 1-year follow-up. In conclusion, although most of these adverse events were minor and self-limited, 78% of right liver donors still experienced morbidity. Therefore, continuous standardized reporting of the donor morbidity as well as meticulous surgery and intensive care are essential for the success of donor RH implementation. Liver Transpl 13:797–806, 2007. © 2006 AASLD.

The second harmonic light of an 842 nm diode laser was generated from a KNbO3 crystal in an external ring resonator. The power of the second harmonic light was about 0.8 mV at an input fundamental power of 87 mW. The laser frequency was stabilized to the resonance frequency of the ring resonator, and the frequency fluctuation was measured as about 3 MHz.

This paper describes tests of precision time transfer using GPS carrier phases. Time comparison experiments were conducted by using a Trimble 4700 geodetic receiver. The internal 10 MHz oscillator of the receiver is disconnected and driven from a hydrogen maser. Time transfer measurements for zero baseline and short baseline were carried out for evaluating the performance of time transfer using the geodetic receiver and applied to the comparison of frequency standards. The results of the time comparison using the receiver has shown that the precision is less than a hundred picosecond. The receiver can be used as a precision time transfer receiver using GPS carrier phases with a longer baseline.

Saturated absorption spectra of the /sup 87/Rb atom under the magnetic field of several tens of gauss were observed with a diode laser oscillating at 780 nm, and Zeeman splittings of the 5/sup 2/P/sub 3/2/ excited state of the atom were numerically calculated to obtain the spectra theoretically. Both of the spectra agreed well, and a Zeeman-shifted absorption line was used for the frequency stabilization of the diode laser. >

We made a clock comparison system using the 10 kHz and 1 pps signal. A frequency divider is used for generating 10 kHz signal from the clocks. Clock comparison is carried out by using the system from MJD 51160 to MJD 51196. We compared the results using the 10 kHz data with those using 1 second data averaged for 10 seconds. The precision of clock comparison was improved by using the clock comparison system.

A method for stabilizing the center frequency of a directly modulated semiconductor laser is described. The laser frequency is locked to a Fabry–Perot etalon by controlling both the injection current and temperature by a frequency error signal simultaneously. The square root of the Allan variance obtained here is 2.5×10−13

A temperature controller for laser diode using modulation of an error signal which is proportional to the difference between the sensor temperature and the setpoint temperature is described. By controlling the amplitude of the modulation signal automatically we obtained a temperature stability of ±60 μK at 22.75 °C in a laboratory environment with temperature variations of about 4 K.

— The a-SiGe TFT photosensor for embedded touch-screen panels (TSPs) was characterized by comparison with an a-Si sensor. The photoresponse of an a-SiGe sensor at a 850-nm wavelength was much higher than that of a-Si, indicating that a-SiGe is a strong candidate material for an IR sensor. In order to increase the signal-to-noise ratio, the incident visible light was filtered by incorporating a bandpass-filter layer. An a-SiGe IR-sensor-embedded LCD panel was successfully demonstrated, showing an excellent multitouch property independent of ambient-light conditions. This technology can be widely used in multifunctional TSPs.

Fabrication of TFT-LCD panels of high resolution and aperture ratio was demonstrated by using a low-k dielectric film as a passivation layer for the first time. The low-k dielectric films were successfully deposited and patterned using a conventional PECVD and plasma-assisted etching techniques, causing no drastic modification to the standard TFT process. Thin film transistors having the a-Si:C:O:H passivation showed a transfer characteristics similar to that of conventional TFT's. The high transmittance panel showed brightness approximately 30% higher than that of a standard panel without degrading other display characteristics, such as cross-talk.

The second-order Zeeman effect produces the largest frequency shift among several causes to alter the reference frequency in the optically pumped cesium beam frequency standard. We introduce a novel way to reduce the uncertainties due to the Zeeman effect by adopting a dual servo system, one for stabilizing the current for static magnetic field and the other for normal clock operation. As a result, the combined uncertainty of the second-order Zeeman frequency shift is reduced to 3.2 ×10-15, which is smaller by one order of magnitude than that without the servo system.

We observed that atomic population was trapped in the ground state of cesium atoms when a σ-polarized laser was illuminated to the atoms under a weak static magnetic field in an optically pumped cesium beam tube. The population trapping could be removed by applying a (σ+π)-polarized laser which was made by superposition of both σ- and π-polarizations. The pumping laser with the (σ+π)-polarization increased the pumping efficiency even in the low magnetic field and accordingly, the background noise of the Ramsey spectrum was reduced by about four times and moreover, the Ramsey signal became more stable against the power fluctuation of the pumping laser.

We observed saturated absorption spectra of the 87Rb atom under a magnetic field of several millitesla with a diode laser oscillating at 780 nm. The spectra were compared with the theoretical ones obtained on the basis of Nakayama's four-level model. We numerically computed Zeeman splittings of the 52 P 3/2 excited state of the atom. As the magnetic field increased to 5 mT, the absorption peak of the F=2→F'=3 transition shifted almost linearly up to about 62 MHz. The shift direction was reversed by changing the polarization combination of the pump and probe lasers. The measured frequency stability, when the laser was locked at the absorption peak, was better than σy(τ)= 1 ×10-11τ-1/2 for the sampling time of 0.01 s≤τ≤10 s.