Kazuhiro Shimaoka

Determination of the Microwave Field Strength Using the Rabi Oscillation for a New Microwave Power Standard

This paper describes the development of a new type of microwave power standard based on atomic resonances. An atomic Rabi frequency is proportional to the magnetic field strength of the resonant microwave; the proportionality constant is determined only from fundamental constants and atomic quantum theory. The microwave field strength that corresponds to microwave power is thus uniquely determined by the Rabi frequency. The proportionality constant can thus serve as the basis for a new microwave power standard. This paper confirmed that the Rabi frequency of cesium-133 (133Cs) atoms in a rectangular cell is proportional to the incident microwave field strength. A rectangular Cs glass cell was developed and inserted into a WR90 waveguide-an industrially practical waveguide that permits the impedance analysis necessary to measure microwave power. The microwave field strength in the Cs cell can be adjusted to arbitrary values proportional to the Rabi frequency. The relative expanded uncertainties of the effective microwave magnetic field strength H eff for the coverage factor k = 2, which is typically less than 7%, averaged 4%. The dynamic range of the available Rabi frequency was 31.9 dB.

Atomic Microwave Power Standard Based on the Rabi Frequency

The Rabi frequency for an atomic hyperfine structure transition is proportional to the magnetic field strength of the incident electromagnetic wave. Using the known proportionality constant, an atomic microwave power standard based on the Rabi frequency can be realized. In this paper, the Rabi frequency of cesium atoms in a glass cell inserted in a microwave waveguide was measured using the atomic-candle method. The Rabi frequency was converted into the incident microwave power via the magnetic field strength by correcting the effects of the glass cell and impedance mismatch. The relative expanded uncertainty was approximately 4% at a coverage factor of 2. The microwave power measured from the Rabi frequency was compared with that measured by a calorimetric method. These results coincided within their uncertainties.

A Broadband Waveguide Calorimeter in the Frequency Range From 50 to 110 GHz

A new broadband rectangular waveguide calorimeter for radio-frequency (RF) power meter calibration in the millimeter-wave region is reported. The calorimeter has a quasi-twin structure exploiting the WR-10 and WR-15 rectangular waveguides, and its operational frequency ranges from 50 to 110 GHz. This calorimeter is characterized by its high measuring speed and sensitivity. A thermal feedback control system reduces the typical reading time per frequency to less than 10 min, and the minimum measurable incident RF power is 0.2 mW. A new technique for reducing the equivalence error by utilizing a flat millimeter-wave absorber is also discussed.

Standards Research in Japan: Latest Development of Millimeter-Wave and Submillimeter-Wave Measurements

In recent communication networks, 100 Gb/s passive optical Ethernet networks have been established and started becoming widely used. In consumer broadcasting, the use of high-definition television in studio and live-relay broadcasts has been planned by the Japanese government. These high-speed wireless technologies require the millimeter-wave frequency band from 30 to 300 GHz to provide sufficient bandwidth. In a wireless link system, spurious signals must be identified and managed in accordance with Japanese Radio Law relating to the recommendations by the International Telecommunication Union Radio section (ITUR). According to the regulations for spurious domain emission in ITU-R SM 329-10 (02/2003), limits on spurious domain emissions for radio equipment over the range of 9 kHz to 300 GHz must be currently considered and tested before being applied. The recommended frequency ranges of spurious domain measurement depend on the fundamental frequency in the wireless link system.

Optimization of the Atomic Candle Signal for the Precise Measurement of Microwave Power

To use the atomic candle signals of Cs atoms for the measurement of microwave power, the main parameters such as a standing or running microwave in the glass cell containing Cs atoms, the probing position in the waveguide, the intensity of the probing laser, the pressure of the

Rabi frequency measurement for microwave power standard using double resonance spectrum

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Optimization of the atomic candle signal used for microwave power standard based on the Rabi frequency

buffer gas, and the beam diameter were optimized. As a result, the average uncertainty in obtaining the Rabi frequency, whose accuracy is important for the measurement of microwave power, was reduced several-fold. We demonstrated the measurement of microwave power using the optimized atomic candle signal in our previous work. In this paper, we discuss the optimization process in detail and the utility of optimizing the atomic candle signal for the precise measurement of microwave power.

A broadband waveguide calorimeter for mm-wave power meter calibration in the frequency range from 50 GHz to 110 GHz

In this paper we describe a basic experiment with the aim of developing a new type of microwave power standard that utilizes atomic resonances. The microwave field strength is determined from the oscillation of the population of atomic quantum states caused by the interaction between a microwave and Cs atoms (Rabi oscillation). A rectangular Cs glass cell was developed for this experiment and inserted in a WR90 waveguide. The observed frequencies of the Rabi oscillation were proportional to the microwave field strength, which demonstrated the feasibility of the new microwave power standard.

Absolute measurement of microwave power based on the atomic rabi frequency

A new microwave power standard using the Rabi frequency of gaseous atoms in a glass cell has been proposed. In this new power standard, the incident microwave power is determined by maximizing the amplitude of the atomic candle signal. Therefore, the line width and signal-to-noise ratio (SNR) of the atomic candle signal are the major parameters determining the measurement uncertainty. In this paper we describe the optimization of the atomic candle signal. Our results show that the accuracy of determination of the Rabi frequency can be improved more than twofold by regulating the intensity of the probing laser.

Calibration of mm-wave power meters using a broadband calorimeter in the frequency range from 110 GHz to 170 GHz

A new broadband rectangular waveguide calorimeter for radio-frequency (RF) power meter calibration in the mm-wave region is reported. The calorimeter has a quasi-twin structure exploiting the WR-10 and WR-15 rectangular waveguides, and its operational frequency ranges from 50 GHz to 110 GHz. This calorimeter is characterized by its high measuring speed and sensitivity. A thermal feedback control system reduces the typical reading time per frequency to less than 10 min, and the minimum measurable incident RF power is 0.2 mW. A new technique for reducing the equivalence error (EE) by utilizing a flat mm-wave absorber is also discussed.