Naimu Kuramochi

Frequency Stabilization of AlGaAs Semiconductor Laser Based on the 85Rb-D2 Line

The frequency of an AlGaAs semiconductor laser was stabilized by using the linear absorption spectrum of the 85Rb-D2 line. By controlling the injection current, the frequency stability of 3.0×10-10σ1.4×10-12 was obtained for 10 msτ500 s. First observation of the saturated absorption spectrum of the 85Rb-D2 line is demonstrated, which can be used as a frequency reference to improve the frequency stability.

Basic study on dispersion and surface modification of diamond powders by sonochemical reaction

When diamond particles are used as abrasive agents, they have to disperse homogeneously. Consequently, many dispersants have been developed to improve the dispersion property of abrasive agents. However, improvement of surface properties of abrasive agents using dispersants is not essential. We attempted an intrinsic surface modification of diamond particles used as abrasive agents by ultrasound exposure. The change of zeta potential by ultrasound exposure was confirmed. Sub-micron diamond particles with average size smaller than 0.1 µm were obtained.

Spectral Profiles of the 87Rb D1 Line Emitted from a Spherical Electrodeless Lamp

Spectral profiles of the 87Rb D1 line (λ=794.8 nm) are observed by a Fabry-Perot interferometer for a spherical electrodeless lamp (BBL type) which contains 2.8 Torr of Kr as a starting gas. Temperature dependence of the spectral profiles is measured and the characteristics of the observed profiles such as the intensity, width and self-absorption of each hyperfine component line are discussed. From the convolution calculation, the equivalent half widths are estimated to be 1.05 GHz for the e and the f lines and 1.25 GHz for the c and the d lines when the lamp surface temperature is 80°C.

Analysis of the effect of foreign gases in the filtering action of a 85 Rb cell

The variation in the 87Rb D1 (λ = 794.8 nm) pumping light profiles due to 85Rb filter cell temperatures (< 80 °C) has been explained by considering both the shift and broadening of the 85Rb absorption spectrum caused by low-pressure foreign gases (< 200 Torr). The coefficients of the pressure shift and broadening by N2 gas were obtained as −8.0 ± 0.5 and 11 ± 1 MHz/Torr, respectively. The intensity ratio and difference of two peaks in the profiles were calculated in order to discuss the variation in the profiles quantitatively. The foreign gas He was examined for comparison. The absorption coefficient of Rb was also discussed.

Signal Intensity Characteristics of the 87Rb Double Resonanace due to the Pumping Light

The depencence of the signal intensity of the 87Rb double resonance on the pumping light which was obtained by a 87Rb lamp and a 87Rb filter cell was measured. It became clear that the signal intensity depended specifically on the kind and pressure of the foreign gas contained in the 87Rb filter cell, and on its temperature. These characteristics correspond to those of the intensity difference of the two hyperfine components of the 87Rb D1 pumping light.

Temperature Dependence of Hyperfine Spectrum of Rb D1 Line

This paper deals with the experimental studies of the rubidium (Rb) spectral lamp for the purpose of getting an excellent pumping light source for a Rb gas cell type frequency standard, or for a Rb microwave maser. Some of Rb lamps containing Ne, Ar, Kr, and Ne-Ar as a carrier gas were made by way of experiment. In order to observe the hyperfine spectrum of D1 line, the Fabry-Perot type scanning interferometer was made, which is driven electrostrictively. The hyperfine components of D1 line were resolved successfully. It was observed that the line which is used as a pumping source became intense as the lamp temperature was raised, and it began to be dipped and decrease, however, over the definite temperature. Also observed was that this optimum temperature differs from the temperature at which the integrated intensity of D1 line shows a maximum.

Spectral Profiles of the 87Rb Pumping Light Source

This paper is concerned with experimental studies of the 87Rb pumping light source, which is composed of a 87Rb lamp and a 85Rb filter cell. Spectral profiles of the pumping light were observed by means of a Fabry-Perot interferometer. Measurements were executed by using ten filter cells which contained 85Rb atoms and various gases (N2, Ar and He) under various pressures. As a result, it became clear that the change of the pumping light spectrum with the filter cell temperature was specific to each cell. When we took note of the ratio and the difference of the two components of Rb D1 line as measures of the filtering effect, the temperature dependence of these values relied on the kind and the pressure of the foreign gas.

Composite-type (87)Rb optical-pumping light source.

A (87)Rb hyperfine optical-pumping light source less than 4 cm long has been fabricated. Features of this new light source are: A 3-7-mm-long (85)Rb filter cell is attached to the front face of a cylindrical (87)Rb lamp with a diameter of 10mm, and both the lamp and the filter cell are operated at the same temperature of about 100 degrees C. A satisfactory spectral profile of D(1)-line output (lambda = 794.8 nm) has been observed by using a Fabry-Perot interferometer.

Effect of the worked layer in quartz-crystal plates on their frequency stabilities

Describes the direct measurement of the relation between the worked layers in quartz-crystal plates and their effect on the frequency stability. The rectangular fundamental 5-MHz AT-cut specimen plates lapped and polished with emery powder and cerium oxide, respectively, were placed in gap-type holders and connected with oscillator circuits, and their frequency stabilities were measured. The frequency stabilities are evaluated by the fractional frequency deviation to the nominal frequency ratio, power spectral density, and the Allan variance. The main results are: 1) The frequency drift due to the worked layer is dealt with as a relaxation process. It can be approximated by a sum of one to three terms of an exponential function. 2) The depth of the worked layer has a large effect not only on the long-term frequency stability but on the medium term in the Fourier frequency range of 10-3 to 10-7 Hz. 3) It does not have a dominant effect on the short-term stability with an averaging time of less than 10 s.

Analysis of the temperature dependence of 87 Rb lamp profiles

The temperature dependence of the spectral profile of the 87Rb D1 line (λ = 794.8 nm) observed by a Fabry-Perot interferometer has been discussed by considering the self-absorption mechanism in the lamp. The Rb lamp is assumed to be composed of two separated portions: One is a spherical core of emitting Rb atoms and the other is an outer layer of the same kind of absorbing atoms surrounding the core. The temperature dependence of the emitted light intensity, intensity difference between two hyperfine peaks, and asymmetry of the self-absorbed profiles are systematically explained in the temperature range of 75 to 125°C. The equivalent absorbing atom layer near the lamp surface is estimated to be 0.5 mm in this model.