温梯法生长的Ti:Al2O3晶体的光谱分析

本文研究了不同掺Ti^3＋浓度对温梯法生长的Ti：Al2O3晶体吸收光谱、荧光光谱和X射线衍射光谱的影响。根据吸收光谱提出了一个色心模型。对比了样品各处420nm荧光谱，发现掺Ti^3＋浓度越大，该处荧光强度越弱，同时解释了420肿处荧光峰的起源。对比了样品各处720nm处的荧光谱，发现掺Ti^3＋浓度越大，该处荧光强度越强。X射线衍射谱（XRD）表明，衍射峰强度随掺Ti^3＋浓度的增大而逐渐增强。     

Studies and improvement of radiation-induced color center dosimeter in LiF

We have studied the properties of the dosimeter which was made of homemanufactured LiF crystal. The crystal was cut into chips and each of which was 6mmX6mmX1mm in size. The value of absorbed dose in LiF was calibrated by alanine/ESR dosimetry. The alanine samples were supplied and measured by National Institute of Metrology. The irradiations were carried out with a cobalt-60 source of 7.4X10¹⁵Bq of Tianjin Technical Physics Institute. The dose-effects of absorbance peaks for F, M, R and N band, in specific dose ranges, can all be expressed as A=bDⁿ, where A is the increase in average optical absorbance; b and n are constant relating to the type of color-centers and the impurity of the crystal. We also study to anneal the crystal after irradiation, stable time is cut down from 24 hr. to 4 hr.     

Femtosecond Laser Induced Rewritable Optical Memory in Silicate Glasses

A novel method for producing rewritable optical memory with ultra-high storage density and ultra-high recording and readout speed is presented. A 120 fs, 800 nm, 1 kHz laser focused by an objective lens is used to produce recording bits in glass with high transmittance contrast. These recording bits can be erased by heat-treatment. The mechanism has been discussed by means of the absorption and electron spin resonance(ESR) spectra of silicate glasses before and after irradiation by the laser. The absorption of glasses increases greatly after irradiation because of color-center generation through multi-photon absorption. ESR spectra shows that the color-center induced in the glass are hole-trapped defects. The color-center disappears when the glass heated because the holes and electrons at traps are released by thermal stimulation and recombine again.     

Theoretical Analysis on the Simultaneous Operation of a Color-Center Laser and a Q-Switched Nd:YAG Laser

The simultaneous operation for the Q- switched Nd: YAG laser at 1.06 and the tunable color-center laser over 1.12～1.26 μm has been realized by using a LiF: F2- color-center crystal both as the Q-switcher for the Nd:YAG laser and as the active medium for the color-center laser. The interaction of the two lasers has been analyzed and calculated with the rate equations. The pulse duration of YAG laser is compressed, in agreement with the experimental results.     

Femtosecond Laser Induced Rewritable Optical Memory in Silicate Glasses

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