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We present the designs and performances of cavity-stabilized lasers at 1555 nm, which are built as the frequency source for a transportable photonic microwave generation system. The frequency instability reaches the thermal noise limit of 10 cm-long vertically held cavity of 7×10−16 at 1 s averaging time, and the beat signal of the two lasers reveals a remarkable linewidth of 185 mHz.
We report photonic microwave generation based on Er:fiber-based optical frequency combs and 1.55 μm ultra-stable lasers. The frequency instability of the 9.6 GHz microwave signals is 3 × 10−15@ 1s, and the synthesized tunable 9.192 GHz signal exhibits an instability of 6.7×10−15 @1s. Further improvement of the photonic oscillators is undergoing.
The Short- and medium-term stability of traditional rubidium atomic clocks are mainly limited by the light shift effect. Based on the Pulsed Optical Pumping (POP) technique, which can be used to reduce the light shift effect, we present a laboratory prototype of 87Rb maser. With preliminary measurement, the frequency stability of the clock is 1.2×10−12 τ−1/2(τ =1∼100s).
We demonstrate a 10-GHz fiber-based photonic microwave generator with residual phase noise below −110 dBc/Hz for Fourier frequencies higher than 2-Hz. The noise floor is reduced to −156 dBc/Hz by using an optical mode-filtering cavity.
The generation of microwaves from optical signals suffers from thermal and shot noise inherent in the photodetection process. This problem is more acute at lower pulse repetition rates where photodiode saturation limits the achievable signal-to-noise ratio. In this paper, we demonstrate a 10–15-dB reduction in the 10-GHz phase noise floor by multiplication of the pulse repetition rate. Starting with...
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