Eisuke Saneyoshi

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Terahertz frequency comb by multifrequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy

Applied Physics Letters (2006)

Takeshi Yasui Yasuhiro Kabetani Eisuke Saneyoshi Shuko Yokoyama Tsutomu Araki

We report a terahertz spectroscopy technique based on a stable terahertz frequency comb from a photoconductive terahertz emitter driven by a stabilized femtosecond laser. To this end, a photocurrent frequency comb is induced in a photoconductive terahertz detector by instantaneous photogating with another detuned femtosecond laser and is applied to read out the terahertz frequency comb. The detailed structure of the terahertz frequency comb was clearly observed with frequency accuracy of 2.5×10−7 and resolution of 81.8MHz using multifrequency-heterodyning photoconductive detection, which in turn is caused by the slightly mismatched frequency spacing between terahertz and photocurrent frequency combs.

Photomixing

Photoconductivity

Photocurrent

Terahertz gap

Terahertz time-domain spectroscopy

Comb generator

10.1063/1.2209718

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Citations (207)

Rapid, ultrahigh-resolution Terahertz time-domain spectrometer based on asynchronous optical sampling method

International Quantum Electronics Conference (2005)

Eisuke Saneyoshi Takeshi Yasui Tsutomu Araki

10.1109/iqec.2005.1561111

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Rapid, Ultrahigh-resolution Terahertz Time-domain Spectrometer Using Two Asynchronous-controlled Femtosecond Lasers

Eisuke Saneyoshi Takeshi Yasui Tsutomu Araki

We propose a novel terahertz time-domain spectrometer using two asynchronous-controlled femtosecond lasers. The proposed spectrometer features ultrahigh-resolution equivalent to a laser mode-locked frequency at rapid data acquisition less than 10 sec based on an asynchronous optical sampling method.

10.1109/icimw.2005.1572536

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A 1.1V 35μm × 35μm thermal sensor with supply voltage sensitivity of 2°C/10%-supply for thermal management on the SX-9 supercomputer

Eisuke Saneyoshi Koichi Nose M. Kajita Masayuki Mizuno

Presented here is a thermal sensor, based on transistor off-leakage current, that allows measurement error of less than 3.1degC at 90degC and less than 2degC at 10% Vdd deviation. For experimental evaluation, 11 thermal sensors, each of which occupied only 35 mum times 35 mum area, were placed on a chip, and both the location of a hotspot and the overall temperature distribution were successfully measured and agreed with simulation.

10.1109/vlsic.2008.4585987

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Citations (31)

Asynchronous optical sampling terahertz time-domain spectroscopy for ultrahigh spectral resolution and rapid data acquisition

Applied Physics Letters (2005)

Takeshi Yasui Eisuke Saneyoshi Tsutomu Araki

We propose a terahertz time-domain spectrometer based on asynchronous optical sampling. The spectrometer features ultrahigh spectral resolution equivalent to a laser mode-locked frequency and rapid data acquisition. The proposed method requires no mechanical translation stages for time-delay scanning, and hence, overcomes the inherent tradeoff between frequency resolution and data acquisition time. Time evolution of the picosecond terahertz pulse with a temporal window of 12.1 ns is measured directly on an oscilloscope using a time-scale magnification of 764 815. A frequency resolution of 82.6 MHz is achieved at a measurement time of 10 s. The effectiveness of the proposed method is confirmed by comparing it with conventional stage-scanning terahertz time-domain spectroscopy.

Picosecond

Temporal resolution

10.1063/1.2008379

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Citations (245)

Anomaly Identification in A Liquid-Coffee Vending Machine Using Electrical Current Waveforms

Yuko Ishii Eisuke Saneyoshi Mitsuru Sendoda Reishi Kondo

This paper proposes an anomaly identification method for a liquid-coffee vending machine using electrical current waveforms. The method consists of preprocessing of a series of current values collected from the machine, training of multiple classifiers corresponding to individual target anomalous operations, and anomaly detection by means of the classifiers. Preprocessing improves detection accuracy by excluding current values that represent non-target operations. Multiple classifiers corresponding to individual target operations are trained using pre-processed data and the ground truth. An operation with the maximum likelihood normalized by the total number of individual operations is identified as the current anomaly. Evaluations using electrical current values obtained from an actual coffee vending machine shows a false positive rate and a false negative rate of, respectively, 0% and 6.7%, for lack of beans and 2% and 0% for water leakage, both of which are major reasons for degraded coffee quality.

Identification

Anomaly (physics)

Data pre-processing

10.1109/infoct.2019.8711414

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Citations (7)

A precise-tracking NBTI-degradation monitor independent of NBTI recovery effect

2022 IEEE International Solid- State Circuits Conference (ISSCC) (2010)

Eisuke Saneyoshi Koichi Nose Masayuki Mizuno

We design an on-chip aging monitor that combines the advantages of the small area of a ring-oscillator-type monitor and the short measurement time of a delay-line type monitor. It offers 1) short measurement time (more than 10x faster than conventional aging monitors, 2) small size (1/6 the size of a delay-line monitor), and 3) strong VDD noise immunity.

Ring oscillator

Degradation

Tracking (education)

Noise immunity

Line (geometry)

Negative-bias temperature instability

10.1109/isscc.2010.5433994

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Citations (37)

High-accuracy, high-resolution terahertz frequency-comb spectroscopy based on multi-frequency-heterodyning photoconductive detection

Yasuhiro Kabetani Takeshi Yasui Eisuke Saneyoshi Shuko Yokoyama Tsutomu Araki

We propose a terahertz (THz) frequency-comb technique for high-accuracy, high-resolution THz spectroscopy, based on multi-frequency-heterodyning (MFH) photoconductive detection using two femtosecond optical frequency combs with slightly mismatched frequency spacing.

Photoconductivity

Optical frequency comb

10.1109/icimw.2006.368632

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