Laser light with spectral purity and frequency stability is pursued in precision spectroscopy and precision measurements. We propose a scheme to generate millihertz-linewidth laser light with a frequency instability of 10−18 via optical four-wave mixing in alkaline-earth atoms. We show that the linewidth of the mixing laser light is ultimately limited by the natural linewidth of the atomic transition rather than by the linewidth of the input lasers. The frequency stability of the mixing laser light depends largely on the intensity stability of the input lasers. It is possible to generate a millihertz-linewidth laser light with a frequency instability of 10−18 and a power of 10−12 W when the input lasers with a relative intensity instability of 10−4 and a spectral width of 1 Hz interact with strontium (Sr) atoms with a density of 1 × 1011 cm−3.
On the basis of the self-interference effect between
±
1
st-order diffraction beams from a
single optical submicrometer grating, we demonstrate a
single-detecting-path optical displacement sensor with high
resolution. Using a quadrant optoelectronic detector, a
single-detecting-path system without any wave plates is realized
experimentally. Combined with an interpolation circuit, we demonstrate
the system for displacement measurement within a range of 200 µm. The
results indicate a detecting sensitivity of 905.4°/µm and an accuracy
of
±
1
.
9
µ
m
. It is worth mentioning that,
considering a maximum subdividing factor of 9674 used in experiment,
the resolution goes down to 41.1 pm in principle. We demonstrate a
compact optical sensor with high resolution, which is promising in
developing miniaturized displacement systems.
In this paper, we present the design, fabrication, and test of a micro-opto-electro-mechanical systems (MOEMS) accelerometer based on the Talbot effect of double-layer diffraction gratings. The detection of acceleration is realized by using the highly sensitive displacement characteristic of Talbot imaging of near-field diffraction with double-layer gratings. For the purpose of obtaining optimal contrast of the optical interferometric detection, the parameters of the gratings are optimized by the finite-difference time-domain (FDTD) simulation. The experimental results indicate that this MOEMS accelerometer with the proposed design can achieve a resolution of 246 µg, sensitivity of 6.1 V/g, and bias stability of 0.02 mg. The proposed accelerometer can be operated at higher accelerations (
∼
80
g
), which shows significant potential for being used in applications that require detection of strong and fast vibrations, especially in vibration sensing of vehicles and geophysical seismic sensing in real time.
We demonstrate a novel, to the best of our knowledge, micro-opto-electro-mechanical system (MOEMS) gyroscope based on the Talbot effect of a single-layer near-field diffraction grating. The Talbot effect of an optical grating is studied both theoretically and experimentally. A structure of grating–mirror combination, fabricated by the micro–nano processing method, is used for out-of-plane structure detection. The detection of a weak Coriolis force is realized by using the highly sensitive displacement characteristic of Talbot imaging of near-field diffraction with a mirror mass block and single-layer grating. The experimental results show that, the micro-displacement detection sensitivity can reach up to 0.09%/nm, and the MOEMS gyroscope can be moved in the driven direction, with a resonant frequency of 7048 Hz and a quality factor of 700, which indicates great potential of the Talbot effect in developing novel high-performance micro-gyroscopes.
We present performance manipulation of the squeezed coherent light source based on four-wave mixing (FWM) in alkaline-earth atoms. We investigate the dynamic response of the system and the spectroscopic feature of lasing generated by resonantly enhanced wave-mixing in coherently prepared system. In this method, the spectral purity and stability of the wave-mixing lasing can be manipulated at will by choosing optimal laser parameters. We also analyze the effect of Langevin noise fluctuations on the system and the relative-intensity noise spectrum of the wave-mixing lasing is well below the standard quantum limit (down to -4.7 dB). This work opens new possibilities for alternative routes to laser stabilization and provides a promising path to realize precision metrology.
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