Polarity switching and transient responses in single nanotube nanofluidic transistors

We report the integration of inorganic nanotubes into metal-oxide-solution field effect transistors (FETs) which exhibit rapid field effect modulation of ionic conductance. Surface functionalization, analogous to doping in semiconductors, can switch the nanofluidic transistors from p-type to ambipolar and n-type field effect transistors. Transient study reveals the kinetics of field effect modulation is controlled by ion-exchange step. Nanofluidic FETs have potential implications in subfemtoliter analytical technology and large-scale nanofluidic integration.     

Experimental observation of classical subwavelength interference with a pseudothermal light source

We report the experimental observation of classical subwavelength double slit interference with a pseudothermal light source. The experimental results are in good agreement with the theoretical simulation using the second order correlation function for the thermal light.     

Four-channel coarse WDM for inter- and intra-satellite optical communications

A polymer volume grating-based four-channel coarse wavelength division multiplexer (WDM) for inter- and intra-satellite optical communication application is reported for the first time. This compact four-channel WDM device working at 0.83, 1.06, 1.34 and 1.55 μm is designed to build a complete optical link between two satellites, where wavelengths of 0.83 and 1.55 μm are used for data stream channels, 1.06 and 1.34 μm are used for inter- and intra-satellite connection. It is for the first time reported that a WDM device can cover such a large wavelength range in a single substrate. For transverse electric (TE) wave, the channel efficiencies at 0.83, 1.06, 1.34 and 1.55 μm are 55%, 40%, 35% and 45%, respectively. Channel efficiencies for transverse magnetic (TM) waves are 20% lower than those of TE waves on average. Wavelength shifts due to Doppler effect, temperature variations and radiation effects in space can be adequately accommodated.     

Determination of the cluster spectroscopic factor of the 10.3 MeV state in 12Be

From an inelastic excitation and breakup experiment with a ¹²Be beam at 29 MeV/u, a large ⁴He+⁸He cluster decay width of 1.1(2) MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0+. By using the R-matrix analysis, a cluster spectroscopic factor of 0.53(10) is extracted from the cluster partial width, providing a strong support for the clustering structure in ¹²Be. A specially designed zero-degree telescope played an essential role in the present experiment and has been demonstrated to be a promising tool in future studies of the molecular-like resonances near the cluster separation threshold.     

Preparation and characterization of carbonyl iron/glass composite absorber as matched load for isolator

Composite absorbers made from 66 wt% carbonyl iron and 34 wt% low melting point glass powder were prepared by a pressureless sintering technique in a nitrogen atmosphere. Apparent porosity and bending strength of the as-prepared composites were investigated. The microstructure, heat resisting properties and electromagnetic properties were characterized by scanning electron microscopy, thermal gravimetric analysis–differential scanning calorimetry and vector network analyzer. The results show that the carbonyl iron/glass composite absorbers were difficult to densify. As the sintering temperature and soaking time increased, the apparent porosity first decreased and then increased, whereas the bending strength showed the opposite change. The composite absorber sintered at 520 °C for 40 min achieved the minimum apparent porosity of 13.08% and the highest bending strength of 52 MPa. Compared to the carbonyl iron/silicone rubber absorber, the carbonyl iron/glass composite absorber exhibited better heat resisting properties, and the initial oxidation temperature was increased about 200 °C. The composite absorber with a thickness of 1.25 mm showed a good microwave absorbing property in 8–12 GHz.     

Pulse width compression and enhancement of peak power in a diode-pumped doubly Q-switched Nd:GdVO<Subscript>4</Subscript> 1.34 μm laser with AO and V<Superscript>3+</Superscript>:YAG saturable absorber

By using both acousto-optic (AO) modulator and V³⁺:YAG saturable absorber, a diode-pumped doubly Q-switched a-cut Nd:GdVO₄ laser at 1.34 μm is realized. The average output power and the pulse width for different AO repetition rate f have been measured. The experimental results show that the doubly Q-switched laser can compress the pulse width and improve the pulsed peak power in comparison to the singly Q-switched laser with AO or V³⁺:YAG saturable absorber. At the pump power 10.34 W and f = 10 kHz, the greatest pulse width compression ratio 72% and the highest peak power improvement 8.8 times have been obtained, respectively.     

The formation of different structures in the interaction between a single femtosecond laser pulse and a thin Au film

The interactions between femtosecond (fs) laser pulses and a thin Au film deposited on a silica glass substrate were systematically investigated based on experimental data. Different structures, including microholes, nanoholes, and nanobumps, are obtained when pulses with different energies are incident on the surface of a gold film. The experimental results are discussed according to specific experimental parameters. Two physical models were constructed in order to explain the experimental results. The formation of nanoholes in a silica substrate is attributed to etching by higher order harmonic generations (HHG) when the femtosecond laser pulse interacts with the generated plasma layer, while the formation of nanobumps on the surface of an Au film is attributed to the elastic and plastic characteristics of the metal film under laser pulse irradiation.     

长腰内锥流量计的特性研究

内锥式流量计在多相流测量中的应用逐渐受到广大多相流研究工作者的重视。针对内锥式流量计在多相流测量中存在的一些问题,提出一种新型的环形通道式差压流量计—长腰内锥流量计。通过理论推导得出流量方程及永久压损与流量的关系式,并通过在水相、油相、气相条件下的标定实验,定量分析流出系数与永久压损等特性。结果表明:在长腰内锥体腰部取低压可以在保证差压信号幅值的情况下提高其稳定性、重复性;长腰内锥流量计节流件的轮廓及固定方式可以显著地减小永久压损。为后期开发新型多相流测量仪器提供理论依据与设计基础。     

Improved λ/4 phase-shifted DFB semiconductor laser with spatial hole burning compensation using grating chirp

A λ/4 phase-shifted distributed feedback (DFB) semiconductor laser with a preformed chirped grating used to compensate the spatial hole burning (SHB) induced index change is proposed and analyzed. It shows that compared with the three phase shifted DFB laser which is known for its good performance to eliminate SHB, the proposed SHB compensated laser has better single longitudinal mode property, narrower spectral linewidth and better dynamic characteristics.