Circulating pulse cavity enhancement as a method for extreme momentum transfer atom interferometry

Large-scale atom interferometers promise unrivaled strain sensitivity to mid-band gravitational waves, and will probe a new parameter space in the search for ultra-light scalar dark matter. These proposals require gradiometry with kilometer-scale baselines, a momentum separation above 104ℏk between interferometer arms, and optical transitions to long-lived clock states to reach the target sensitivities. Prohibitively high optical power and wavefront flatness requirements have thus far limited the maximum achievable momentum splitting. Here we propose a scheme for optical cavity enhanced atom interferometry, using circulating, spatially resolved pulses, and intracavity frequency modulation to meet these requirements. We present parameters for the realization of 20 kW circulating pulses in a 1 km interferometer enabling 104ℏk splitting on the 698 nm clock transition in 87Sr. This scheme addresses the presently insurmountable laser power requirements and is feasible in the context of a kilometer-scale atom interferometer facility.

Tensoresistive properties of single crystals TlIn1−xGaxSe2

In this work, single crystals of TlIn[Formula: see text]Ga[Formula: see text]Se2 solid solutions were grown by the methods of zone recrystallization, technologies for the manufacture of strain gauges based on them were developed and the tensoresistive properties of these phases were studied, the coefficient of strain sensitivity was determined by the static method depending on the temperature, the magnitude of mechanical deformation and optical illumination. Revealing that the single crystals have a high strain sensitivity coefficient, by the variation of the composition, quantity of mechanical deformation and the optical illumination, it is possible to control the phase coefficients investigated tensosensitivity.

Strain gages based on gallium arsenide whiskers

Strain-resistant properties of GaAs whiskers and ribbons of p- and n-type conductivity with various length (0.3–7 mm) and diameter (10–40 μm) have been investigated in a wide range of temperatures. Strain gages based on heavily doped p-type conductivity GaAs whiskers have linear deformation characteristics and a weak temperature dependence of strain sensitivity in the temperature range from –20 to +3500 °C. The temperature coefficient of resistance (TСR) of not fixed strain gages is about +(0.12–0.16)% × grad–1. The temperature coefficient of strain sensitivity is –0.03 % × deg–1 in the temperature range –120+800 °C. Strain gages based on n-type GaAs ribbons are characterized by high flexibility and high strain sensitivity. They are capable up to +4000 °C and can be used to measure deformations on curved surfaces at high temperatures. TСR of not fixed strain gages is –0.01 +0.03 % × grad–1. The temperature coefficient of strain sensitivity is –0.16% × deg–1 in the temperature range –120 ... +4000 °С.

Study of a Long-Gauge FBG Strain Sensor with Enhanced Sensitivity and Its Application in Structural Monitoring

A long-gauge fiber Bragg grating (FBG) strain sensor with enhanced strain sensitivity is proposed, which is encapsulated with two T-shaped metal blocks. Its fabrication method is described briefly, and the strain sensitivity can be flexibly adjusted through changing its packaging method. A series of experiments are carried out to study the packaging and its sensing properties. The experimental results show that the strain and temperature sensitivity coefficient of the sensor are three times larger than the common FBG sensors. The linearity coefficients of the FBG sensor are larger than 0.999, and the relative error of the repeatability of all sensor samples is less than 1%. Through the stability test on the actual bridge, it is revealed that the long-term stability of the sensor is excellent, and the maximum error is less than 1.5%. In addition, the proposed FBG strain sensors are used to conduct a shear strengthening experiment on a reinforced concrete (RC) beam to verify its working performance. The experimental results show that the strain change and crack propagation of the RC beam are well monitored by the sensors during the loading process.