Showing papers by "Kazuro Kikuchi published in 1995"
TL;DR: It was shown that depolarization induced by the high concentration of potassium caused an increase in the intensity of biochemiluminescence from the rat hippocampal slice, and that suppression of neural activity by tetrodotoxin elicited a decrease of its luminescence.
Abstract: From any kind of living organisms, very weak spontaneous light emission without excitation light (ultraweak biochemiluminescence) is observed. We succeeded to detect ultraweak biochemiluminescence from rat hippocampal slice preparation at the order of 10(-19) W/mm2 by a single-photon detector using a silicon avalanche photodiode. It was shown that depolarization induced by the high concentration of potassium caused an increase in the intensity of biochemiluminescence from the rat hippocampal slice, and that suppression of neural activity by tetrodotoxin elicited a decrease of its luminescence. These findings suggest that correlation between the intensity of ultraweak biochemiluminescence and neural metabolic activity.
90 citations
TL;DR: In this article, a Si avalanche photodiode (APD) detector using a trans-impedance type front-end circuit was employed in order to achieve a high signal-to-noise ratio.
Abstract: A single‐photon detector using a Si avalanche photodiode (APD) has been constructed. A trans‐impedance type front‐end circuit was employed in order to achieve a high signal‐to‐noise ratio. The APD and front‐end circuit were cooled in liquid nitrogen to reduce dark count rate and circuit noise. The system performances were measured, and the achieved dark count rate and total quantum efficiency were 0.08 count/s and 5%, respectively. The sensitivity was evaluated to be of the order of 10−19 W. The APD single‐photon detector was demonstrated to be available for measurement of the ultraweak biochemiluminescence at the order of 10−19 W/mm2 from brain slices, i.e., hippocampal slices. It was shown that the addition of tetrodotoxin to the hippocampal slice caused a decrease in the intensity of biochemiluminescence.
56 citations
TL;DR: In this paper, the authors observed the quasi-phase matched four-wave mixing in a long-distance optical amplifier chain and measured the spectrum of amplified spontaneous emission measured by using a recirculating fiber loop.
Abstract: We observe the quasi-phase matched four-wave mixing in a long-distance optical amplifier chain. The spectrum of amplified spontaneous emission measured by using a recirculating fiber loop shows the enhancement of noise at well-defined frequencies where the quasi-phase matching condition is satisfied owing to the periodic power variation along the fiber link. >
29 citations
TL;DR: In this article, the gain spectrum of a Brillouin fiber amplifier in the saturated region was investigated, and it was shown that a hole is created in the single-pass gain spectrum, and peaks appear at frequencies determined mainly from the round-trip time of the amplifier.
Abstract: We investigate theoretically the gain spectrum of a Brillouin fiber amplifier in the saturated region. When the amplifier is operated in the saturated region a hole is burned in the single-pass Brillouin gain spectrum, and peaks appear at frequencies determined mainly from the round-trip time of the amplifier, causing modulation instability in the amplified signal. This type of modulation instability originates intrinsically from signal amplification by the counterpropagating pump beam, which is depleted by the strong signal beam.
27 citations
TL;DR: In this paper, the authors present a method for designing long-distance optical transmission systems with midway optical phase conjugation, and show that the effective waveform distortion compensation can be achieved by properly designing the amplifier spacing and the fiber dispersion to minimize the effect of the sideband instability.
Abstract: We present the method for designing long-distance optical transmission systems with midway optical phase conjugation. The main cause of the waveform distortion in this type of system is found to be the sideband instability that is induced by the periodic signal power variation along the fiber link. It is shown that the effective waveform distortion compensation can be achieved by properly designing the amplifier spacing and the fiber dispersion to minimize the effect of the sideband instability. >
16 citations
Proceedings Article•
21 May 1995
2 citations