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A microwave atomic clock based on 113Cd+ ions at Tsinghua University is carried out for seven years. To further improve the performance of the clock, a new experimental setup with dual traps and dual species ions was proposed. To investigate the efficiency of sympathetic cooling and the dynamic process of ions, numerical simulation study of the dual-species ion ensembles by the Molecular-dynamics...
A lin-par-lin Ramsey-CPT microwave atomic clock with dispersion detection is investigated in this paper, in which high signal contrast and narrow linewidth are obtained. The pulsed transmitted laser is synchronously detected by a sample-and-hold amplifier and a lock-in amplifier. The frequency shift of the microwave, represented by the output of the lock-in amplifier is acquired. An instability is...
Microwave frequency standard based on laser-cooled 113Cd+ ions has promising performance. The fluorescence decays during detection are one of main limits to the signal-to-noise ratio (SNR) of clock signal. This phenomena is assumed cause by detection laser. We try to verify this assumption by rate equations. Two mathods to improve SNR are also proposed.
We report a high-precision measurement of the ground-state hyperfine splitting of 113Cd+ ions. This result is vital for an atomic clock based on the cadmium ions to estimate the frequency uncertainty.
When a femtosecond laser is servoed onto an ultra-stable cw laser, its repetition rate acquire an extreme spectral purity. By photodetecting the pulses, we are able to generate ultra-low phase noise microwave signals and use it for cutting edge metrology experiments. We present our past and present work to generate microwave signal with very low degradation from the limit imposed by the reference...
Low-phase-noise and stable microwave signals are of prime importance in a variety of scientific and technological fields, such as, for example, atomic frequency standards1,2, radar and remote sensing, and very long baseline interferometry. The combination of ultra-stable lasers 3 and low noise optical frequency division by use a femtosecond laser presents a possibility to realize extremely low phase...
We present our results on optical to microwave frequency division by fiber-based optical frequency combs. The phase noise added by the division process is characterized and several noise reduction strategies are demonstrated. We reach -123dBc/Hz at 1Hz from a 11.55GHz carrier and about -130dBc/Hz above 200Hz Fourier frequency. The fractional frequency stability scales as 1.1×10-16τ-1T where t is the...
We report on our fiber-based mode-locked laser approach to the generation of ultra-low noise microwave signals, and its use for frequency metrology. We make use of two erbium fiber mode-locked lasers phase locked to a common ultra stable laser source to generate an 11.55 GHz signal with a relative phase noise of −111 dBc/Hz at 1 Hz from the carrier. The corresponding residual frequency instability...
An index-coupled distributed feedback laser with the sampled grating has been designed and fabricated. The +1st order reflection of the sampled grating is utilized for laser single mode operation, which is 1.5329 mum in the experiment. The sampled grating is formed by a conventional holographic exposure combined with the usual photolithography. The typical threshold current of DFB laser with the sampled...
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