Trapping and Driving Individual Charged Micro-particles in Fluid with an Electrostatic Device

A variety of micro-tweezers techniques, such as optical tweezers, magnetic tweezers, and dielectrophoresis technique, have been applied intensively in precise characterization of micro/nanoparticles and bio-molecules. They have contributed remarkably in better understanding of working mechanisms of individual sub-cell organelles, proteins, and DNA. In this paper, we present a controllable electrostatic device embedded in a microchannel, which is capable of driving,trapping, and releasing charged micro-particles suspended in microfluid, demonstrating the basic concepts of electrostatic tweezers. Such a device is scalable to smaller size and offers an alternative to currently used micro-tweezers for application in sorting, selecting, manipulating, and analyzing individual micro/nanoparticles. Furthermore, the system offers the potential in being combined with dielectrophoresis and other techniques to create hybrid micro-manipulation systems.

Solid-state-reaction fabrication and properties of a high-doping Nd:YAG transparent laser ceramic

High-quality neodymium-doped yttrium aluminum garnet(Nd:YAG)transparent ceramic(4.0 mole percent)was fabricated by a solid-state reaction method and vacuum sintering.The microstructure,optical transmittance,spectral properties and laser performance were investigated.The average grain size of the sample is about 10 mm.The transmittance of a 2.8-mm thick sample reaches 79.5%at the laser wavelength of 1064 nm.The highest absorption peak is centered at 807 nm and the absorption coefficient is 13.9 cm^(-1).The absorption coefficient at the laser wavelength is 0.2 cm^(-1).The main emission peak is at 1064 nm and the fluorescence lifetime is 102 ms.A laser diode(808 nm)whose maximum output is about 1000 mW was used as a pump source and an endpumped laser experiment was performed.The 1064 nm-CW-laser output was obtained and the threshold is 733 mW.With 998 mW of maximum absorbed pump power,a laser output of 17 mW is obtained with a slope efficiency of 6.1%.

Integrated optical-readout of a high-Q mechanical out-of-plane mode

The rapid development of high-QM macroscopic mechanical resonators has enabled great advances in optomechanics.Further improvements could allow for quantum-limited or quantum-enhanced applications at ambient temperature.Some of the remaining challenges include the integration of high-QM structures on a chip,while simultaneously achieving large coupling strengths through an optical read-out.Here,we present a versatile fabrication method,which allows us to build fully integrated optomechanical structures.We place a photonic crystal cavity directly above a mechanical resonator with high-QM fundamental out-of-plane mode,separated by a small gap.The highly confined optical field has a large overlap with the mechanical mode,enabling strong optomechanical interaction strengths.Furthermore,we implement a novel photonic crystal design,which allows for a very large cavity photon number,a highly important feature for optomechanical experiments and sensor applications.Our versatile approach is not limited to our particular design but allows for integrating an out-of-plane optical read-out into almost any device layout.Additionally,it can be scaled to large arrays and paves the way to realizing quantum experiments and applications with mechanical resonators based on high-QM out-of-plane modes alike.