高性能大口径顺磁旋光玻璃

High Performance Large Aperture Paramagnetic Faraday Rotatory Glass

旋光玻璃广泛用于激光的调制、偏转、开关和高功率激光系统的隔离器。旋光玻璃的主要性质为费尔德常数。含高顺磁离子的旋光玻璃具有大的费尔德常数，可见区高透过等优点。具有较大磁矩和较低f-d跃迁能隙的顺磁离子铽应具有大的费尔德常数。本工作以高Tb2O3含量的TbO3-B2O3-Al2O3-SiO2为基本系统。研究玻璃的形成；测定了不同Tb^3＋离子浓度时的费尔德常数，符合线性关系；调整玻璃组成以避免析晶，发展了波长632nm的费尔德常数为75．1～116．4rad／（T·m）的TG20，TG28，TG32旋光玻璃系列。建立了10升规模铂坩埚高温熔炉，成形和退火设备。形成口径30cm旋光玻璃的生产能力。产品的1054nm光吸收小于0．008cm2，1ns的激光破坏阈值大于8J／cm2，透过波前畸变小于五分之一波长。所制造的旋光玻璃已用于美国Lawrence Livermore国家实验室，中国“神光Ⅱ”升级，英国Rutherford实验室的Vulcan Laser System和CNRSCEA Luli等高功率激光系统。

Faraday rotatory glass has been used for modulating, deflecting of laser, optical switch and isolator. The main property of Faraday rotatory glass is the Verdet constant. Faraday rotatory glass containing high paramagnetic ion concentration is of the large Verdet constant, transparency in the visible region of light. Terbium ion with larger magnetic moment and lower f-d transition energy gap should possess the large Verdet constant. Based on the Tb2 O3 - B203-Al2O3-SiO2 system with high terbium oxide content, the glass formation region was determined and a linear relation between Tb3＋ concentration and the Verdet constant was established. Faraday rotatory glass series of TG20, TG28 and TG32 with the Verdet constant of 75. 1-116. 4 rad/（T·m） was developed by modifying the glass composition to avoid devitrification. A melting furnace of 10 liters platinum crucible, forming apparatus and fine annealing skin were built up to produce 30 cm aperture Faraday rotatory glass. The glass is provided with an optical absorption coefficient of less than 0. 008 cm-1 at 1054 nm, a laser damage threshold of larger than 8 J/cm2 at 1 ns pulse width, a transmitted wavefront distortion of less than λ/5 at 632 rim. The glass has been used for high power systems of LLNL in US, upgraded ＂Shenguang Ⅱ ＂ in China, Vulcan laser system of Ruthorford Lab. In UK and Luli Laser System of CNRS, CEA in France.