196,099 research outputs found
6/12-channel Synchronous Digital Phasemeter for Ultrastable Signal Characterization and Use
No full textNowadays, in primary time and frequency laboratories we can find high spectral purity signals in the 10 MHz - 10 GHz range generated from cryogenic oscillators or ultra-stable lasers together with frequency combs. Their short-term stability surpasses by one to two orders of magnitude the performances of active hydrogen masers (AHM), while in the long-term AHMs still have a better behavior. The new technology can be considered mature for what concern spectral purity, but we cannot say the same about complexity, power consumption and reliability. In this sense, it is important to measure ultra-stable sources with respect to AHMs. First, to test their spectral purity or, at least, to give it an upper bound; second to have a continuous monitoring; finally, to combine them in order to get the best of all in term of phase noise and frequency stability. All of these requirements can be satisfied by the system we are developing. It is a multi-channel synchronous and real-time phasemeter based on Tracking Direct Digital Synthesizer (TDDS) technique. The results related to the first prototype are presented
Negotiation support for make-to-order operations in business-to-business electronic commerce
No full textThis paper deals with the problem of supporting negotiations among manufacturing firms that operate on a Make To Order (MTO) basis. First, an analytical model of negotiation between a generic customer–supplier pair is presented. Then, the paper proposes a system based upon an intervenor which allows the parties to reach efficient utility-sharing solutions. Results of numerical experiments in an industrial environment are reported
Negotiation support for make-to-order operations in Business-to-Business electronic commerce
No full textDirect Measurement of Laser Noise Spectrum with a Frequency-to-Voltage Converter
No full textThe stability performance of laser-pumped Rb-cell atomic clocks is affected by the laser spectral characteristics. It is then important to investigate the laser spectrum, especially since laser noise measurements are rarely found in the literature. We present a frequency-noise power spectrum characterization of a laser diode currently employed in a high-performing Rb clock. The measurement is performed by using a narrow-linewidth reference laser. The beatnote between the two sources is processed with a custom frequency-to-voltage (f/V) converter whose output is finally digitized with an FFT spectrum analyzer
All-optical microwave feedback oscillator with atomic cell resonator
No full textWe report the demonstration of an all-optical self-sustained cell-based microwave feedback oscillator. In this scheme, a microwave reso
nance, optically induced in a buffer-gas filled vapor cell resonator through coherent population trapping (CPT), is detected by a fast photodi
ode, amplified, and used to drive back, through a frequency divider, a Mach–Zehnder electro-optic modulator in a sustaining loop
configuration. The total gain and phase of the system was measured in an open-loop configuration with a network analyzer. In good agree
ment with values predicted by the Leeson effect, the CPT feedback oscillator demonstrates an absolute phase noise of 24 dBrad2/Hz at
1Hz offset frequency, compatible with a fractional frequency stability of 8 10 12 at 1 s, and a phase noise floor of 112 dBrad2/Hz, limited
by the low microwave power available at the photodiode output. The amplitude noise of the oscillator shows a comparable noise floor and,
for offset frequencies lower than 200Hz, a 1/f dependence, due to the presence of the frequency divider in the loop
Frequency-doubled Laser System at 780 nm for Pulsed Vapor-cell Clocks
No full textWe present the development status of a low-noise pulsed laser source suitable for high-performing vapor-cell clocks. The laser is based on a 1560 nm source, frequency doubled to be resonant with the D-2 line of rubidium at 780 nm. The laser system is able to deliver laser pulses with programmable amplitude and length. The intensity noise of the laser during the pulses duration is also actively reduced by means of the same fast analog control loop generating the pulses. The pulses characteristics are shown to be compatible with the specifications of a high-performing Pulsed Optically Pumped (POP) clock
Bene e coscienziosamente: Achille Bertini Calosso, Soprintendente ai Monumenti e alle Gallerie dell’Umbria. Tutela e valorizzazione del patrimonio culturale umbro
No full textMuochrony: timing with muons - First experimental results at INRIM on the synchronization of atomic clocks and dissemination of reference timescales
No full textFrequency noise characterization of diode lasers for vapor-cell clock applications
No full textThe knowledge of the frequency noise spectrum of a diode laser is of interest in several high-resolution experiments. Specifically, in laser-pumped vapor-cell clocks, it is well-established that the laser frequency noise plays a role in affecting clock performances. It is then relevant to characterize the frequency noise of a diode laser since such measurements are rarely found in the literature and hardly ever provided by vendors. In this article, we describe a technique based on a frequency-to-voltage (f/V) converter that transforms the laser frequency fluctuations into voltage fluctuations. In this way, it is possible to characterize the laser frequency noise power spectral density (PSD) in a wide range of Fourier frequencies, as required in cell clock applications
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