Pan Shilie

A study on the real-time radiation dosimetry measurement system based on optically stimulated luminescence

The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions.

First-Principles Assisted Prediction of the Nonlinear Optical Behavior of Mg3B7O13Cl Crystal

In order to explore new nonlinear optical (NLO) crystals with superior performance, it is greatly desirable to understand the intrinsic relationship between the microscopic structural features and ...

Deep-ultraviolet nonlinear optical materials: Development trend and innovative exploration

With the rapid development of all-solid-state laser technology in the field of optical communication, optical processing and optical storage, deep-ultraviolet (deep-UV, wavelengths below 200 nm) nonlinear optical (NLO) materials have become a hot topic at home and abroad. Coherent radiation in the deep-UV is possible with excimer lasers, e.g., F2 excimer at 157 nm. However, solid-state lasers in these wavelength ranges are often preferred owing to handling ease, narrow bandwidth, tunability, high energy density, and high peak power density. An excellent manner to generate coherent deep-UV light is through solid-state lasers using cascaded frequency conversion with NLO materials. Deep-UV NLO crystals, which can double the frequency of incident light to the deep-UV region, are essential for all-solid-state laser. The prerequisites for deep-UV NLO crystals are crystallographically noncentrosymmetric (NCS), wide optical transparency window, large second harmonic generation (SHG) response, phase- matching capability, and easy growth of large (centimeter size) high quality single crystals. For years, there has been a “200 nm wall”, that is, no material is available for deep-UV SHG. Over the past decades, great efforts have been made on chemical design and synthesis of deep-UV NLO materials. Currently, only KBe2BO3F2 (KBBF) crystal is capable for generating deep-UV light through direct sixth harmonic generation of the Nd:YAG laser. The infinite ∞[Be2BO3F2]− single layers in KBBF provide a relatively large SHG coefficient ( d 11=0.47 pm/V) and a sufficient birefringence (Δ n =0.07@1064 nm). However, the KBBF crystals have insurmountable intrinsic defects, such as the high toxicity of the beryllium oxide, and the serious layer growth habit, which greatly restrict its commercialization and application process. Therefore, researchers are actively exploring the next generation of deep-UV NLO materials. In this review, we will first briefly discuss the history of deep-UV NLO crystals. The main factors that restrict the development of deep-UV NLO crystals were highlighted, emphasizing one of the greatest challenges after the material is synthesized is its large single-crystal growth. In the second section, we will focus on progress and trend of deep-UV NLO materials in recent ten years and divide them into different categories according to different material systems and structural features. Five groups of materials are given—beryllium borates, beryllium-free borates, carbonate-fluorides, phosphates and fluorooxoborates. The absorption edge, powder SHG efficiency and birefringence of these materials are summarized in detail. In this section, the development of fluorooxoborates is discussed and the important achievements are reviewed systematically. In addition, the major contradictions among bandgap, NLO coefficient and birefringence were discussed and the methods of theoretical structure prediction algorithms for solving these problems were proposed in order to provide reference for discovering new deep-UV NLO materials.

ELECTRONIC STRUCTURE AND LINEAR OPTICAL PROPERTIES OF MIXED ALKALI-METAL BOROPHOSPHATES (LiK2BP2O8, Li3K2BP4O14): A FIRST-PRINCIPLES STUDY

LiK2BP2O8 and Li3K2BP4O14 are synthesized by high-temperature solution method with the same elements, while contain different fundamental building units. Li3K2BP4O14 is a novel P-O-P linking structure which gives a rare example of violation of Paulings fourth rule. The electronic structures of LiK2BP2O8 and Li3K2BP4O14 are investigated by density functional calculations. Direct gaps of 5.038 eV (LiK2BP2O8) and 5.487 eV (Li3K2BP4O14) are obtained. By analyzing the density of states (DOS) of LiK2BP2O8 and Li3K2BP4O14, the P-O-P linking in fundamental building units of Li3K2BP4O14 crystal is proved theoretically. Based on the electronic properties, the linear optical information is captured.