Enhancing UV photosensitivity of a ZnO UV nanosensor using electrical stimulation at megahertz frequency

We report a novel technique to enhance the ultraviolet (UV) photosensitivity of a ZnO nanosensor with ZnO nanowires bridged on micromachined metallic electrodes. The experimental results reveal that the photoconductivity and the time response of the ZnO nanowire sensor with either Schottky or Ohmic contacts are significantly improved by electrifying the nanowire sensors using an alternating current at the frequency of megahertz. An integrated UV sensor incorporating ZnO nanowires with a constant current mode driving circuit is developed, which demonstrates promising sensitivity and time response to UV illumination with a low power consumption.     

Tunable optical filter using second-order micro-ring resonator

In this paper, we design and fabricate a silicon integrated optical filter consisting of two cascaded micro-ring resonators and two straight waveguides. Two micro-heaters are fabricated on the top of two micro-rings respectively, which are employed to modulate the micro-rings to perform the function of a tunable optical filter by the thermo–optic effect. The static response test indicates that the extinction ratio and 3-d B bandwidth are 29.01 d B and 0.21 nm respectively, the dynamic response test indicates that the 10%–90% rise and 90%–10% fall time of the filter are 16 μs and 12 μs, respectively,which can meet the requirements of optical communication and information processing. Finally, the power consumption of the device is also characterized, and the total power consumption is about 9.43 m W/nm, which has been improved efficiently.     

基于车载原子重力仪的外场绝对重力快速测绘研究

地球重力场信息是大地测量学、地球物理学、地球动力学等学科所必需的重要基础信息,重力场测绘是获取地球重力场信息的有效手段.相比于卫星、海洋、航空重力场测绘,车载重力场测绘具有灵活性强、空间分辨率高、精度高等优点.基于相对重力仪和高精度绝对重力基准点可以实现陆域小范围重力场测绘,但相对重力仪存在零点漂移,不适用于长基线、大范围的陆域测绘.本文基于小型化原子重力仪搭建了一套车载绝对重力快速测绘系统,在郊区安静外场环境,由12个测点约3 km的测绘结果评估仪器的内符合精度为0.123 mGal (1 Gal=10^–2 m/s~2),外符合精度为0.112 mGal,并在闹市复杂外场环境下实现了单点调节时间小于2 min,有效测量时间5 min的快速绝对重力测量,通过19个测点跨区约24 km的重力场快速测绘,评估仪器的内符合精度为0.162 mGal,外符合精度为0.169 mGal.最后将原子重力仪的外场重力场测绘数据与卫星重力模型计算的数据进行了比较,发现两者的自由空间重力异常数据的整体变化趋势相吻合.本文为外场绝对重力场快速测绘提供了一种新的方案.     

Enhancing UV photosensitivity of ZnO UV nanosensor using electrical stimulation at megahertz frequency

We report a novel technique to enhance the ultraviolent (UV) photosensitivity of ZnO nanosensor with ZnO nanowires bridged on micromachined metallic electrodes. The experimental results reveal that the photoconductivity and the time response of the ZnO nanowire sensor with either Schottky or Ohmic contacts are significantly improved by electrifying the nanowire sensors using an alternating current at the frequency of megahertz. An integrated UV sensor incorporating ZnO nanowires with a constant current mode driving circuit is developed, which demonstrates promising sensitivity and time response to UV illumination with a low power consumption.