Portable Atmospheric Transfer of Microwave Signal Using Diode Laser with Timing Fluctuation Suppression

We demonstrate an atmospheric transfer of microwave signal over a 120 m outdoor free-space link using a compact diode laser with a timing fluctuation suppression technique.Timing fluctuation and Allan Deviation are both measured to characterize the instability of transferred frequency incurred during the transfer process.By transferring a 100 MHz microwave signal within 4500 s,the total root-mean-square(RMS)timing fluctuation was measured to be about 6 ps,with a fractional frequency instability on the order of 1×10-12 at 1 s,and order of 7×10-15 at 1000 s.This portable atmospheric frequency transfer scheme with timing fluctuation suppression can be used to distribute an atomic clock-based frequency over a free-space link.

Arrival time fluctuation of higher order normal modes caused by solitary internal waves

The sensitivities of the normal modes arrival time to solitary internal waves （IWs） are analyzed by using the SW06 environments. Simulation results show that the arrival time of mode 1 is relatively stable. But, there are some higher-order normal modes which arrive earlier than mode 1, and fluctuate with the appearance of solitary IWs. Explanation of the phenomenon is given based on ray theory. It is shown that, when thermocline falls down to some depths, those higher-order modes with a group of definite grazing angles mainly propagate above the thermocline and arrive earlier.

Timing fluctuation correction for the front end of a 100-PW laser

The development of high-intensity ultrafast laser facilities provides the possibility to create novel physical phenomena and matter states.The timing fluctuation of the laser pulses is crucial for pump–probe experiments,which is one of the vital means to observe the ultrafast dynamics driven by intense laser pulses.In this paper,we demonstrate the timing fluctuation characterization and control of the front end of a 100-PW laser that is composed of a high-contrast optical parametric amplifier(seed)and a 200-TW optical parametric chirped pulse amplifier(preamplifier).By combining the timing jitter measurement with a feedback system,the laser seed and preamplifier are synchronized to the reference with timing fluctuations of 1.82 and 4.48 fs,respectively.The timing system will be a key prerequisite for the stable operation of 100-PW laser facilities and provide the basis for potential pump–probe experiments performed on the laser.

Discussion on the paper “Analyzing short time series data from periodically fluctuating rodent populations by threshold models: A nearestblock bootstrap approach”

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Discussion on the paper “Analyzing short time series data from periodically fluctuating rodent populations by threshold models: A nearestblock bootstrap approach”

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