物理学报Issue(20)：1-8,8.DOI:10.7498/aps.64.200701
基于探针光调制的皮秒分辨X-ray探测方法与实验∗
Picosecond resolving detection method and experiment for ultrafast X-ray by modulation of an optical probe
摘要
Abstract
Diagnostic measurement of single picosecond event in high energy density physics, laser fusion, plasma radiation, and combustion, is of great importance. However, the measuring of the shape of the single X-ray pulse and the synchronization of X-ray and the laser pulse in picosecond resolution is still a great challenge. Restricted by the transit time of electrons, the time-resolution limit of a conventional framing camera based on the microchannel plate is 40 ps. Centered on the full-optical modulation effect of the light-probe, a novel method for X-ray detection of picoseconds temporal resolution based on low temperature GaAs is proposed in this work. The basic physical mechanism of the detector can be explained in both macroscopical and microcosmic ways. In the macroscopical way, the X-ray radiation absorption in the sensor material produces a transient, non-equilibrium electron-hole pair distribution that results in a transient differential change of the local refractive index, which is then sensed by the reflectivity changes of the optical probe beam. In the microcosmic way, X-ray absorption creates photoelectrons and the core level holes are subsequently filled through Auger or fluorescence processes. These excitations ultimately increase conduction and valence band carriers that perturb optical reflectivity. To verify the proposed X-ray detection method, a Fabry-Perot detector is designed, which consists of a 5 µm thick GaAs layer surrounded by a GaAs/AlAs distributed Bragg reflector. The test is carried out on a femtosecond laser facility, where the X-ray source is produced by focusing the 56 fs Ti: Sapphire facility laser, with a central wavelength of 800 nm, onto an aluminum foil. Then the X-ray pulse induces a transient optical reflectivity change in GaAs, which is a powerful tool for establishing the high-speed X-ray detection. The experimental results indicate that this technology can be used to provide X-ray detectors with a temporal resolution of tens of picoseconds. By optimizing the material, the temporal resolution can be enhanced to be less than 1 ps. Through further development, this X-ray detector could provide an insight into previously unmeasurable phenomena in many fields. Future work will focus on developing much faster devices characterizing both the rise and fall time and imaging array technology.关键词
全光调制/时间分辨/X-ray探测Key words
all optical modulation/temporal resolution/X-ray detection引用本文复制引用
王博,白永林,曹伟伟,徐鹏,刘百玉,缑永胜,朱炳利,候洵..基于探针光调制的皮秒分辨X-ray探测方法与实验∗[J].物理学报,2015,(20):1-8,8.基金项目
国家自然科学基金(批准号:11305259,11327303)和财政部重大科研装备仪器项目资助的课题 （批准号:11305259,11327303）
