可擦写型双层相变光盘的前记录层(激光入射面的记录层,或称前层)需要一个相变光记录层。该记录层具有高投射率的反射率反差[设结晶部的反射率为Rcry、非结晶部的反射率为Ramo,则反射率反差的定义为(Rcry-Ramo)/(Rcry+Ramo)]。从激光入...可擦写型双层相变光盘的前记录层(激光入射面的记录层,或称前层)需要一个相变光记录层。该记录层具有高投射率的反射率反差[设结晶部的反射率为Rcry、非结晶部的反射率为Ramo,则反射率反差的定义为(Rcry-Ramo)/(Rcry+Ramo)]。从激光入射面来看,该前层的结构依次是ZnS-SiO_2层、界面层、GeTe-Sb_2Te_3相变材料层(6nm)、界面层、Ag合金反射层(10nm)。和传统的结构相比,其特点是最上层为具有稿投射率的TiO_2层(20nm)。TiO_2层与反射层之间可产生光学干涉,非晶部和结晶部可实现高投射率,分别达到54％和51％。而且,为了增大反射率反差,采用使信号极性成为Rcry>Ramo的所谓“High to Low结构”,获得了超过0.7的巨大的反射率反差(Ramo=0.7％,Rcry=5.7％)。该前层采用波长405nm、NA=0.85的光学系统,记录最短标记(记录畴)长为0.149μm的1-7PP调制信号(双层相当于50GB的密度)时,在10mW的记录功率条件下,可获得7.4的抖晃值。展开更多
A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incid...A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incident plane.The results showed that it was linearly polarized.We established a surface current model to explain this phenomenon,assuming that the transient current moving along the plasma surface was responsible for the generation of the THz emission.The model expectation and the experimental result were in good agreement.展开更多
The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold charac...The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold characteristics of VCSELs with various proton implanted depths are studied after optical,electrical and thermal fields have been simulated self-consistently in three dimensions.It is found that for VCSELs with confinement radius of 2 mm,increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region.Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs.The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 mm,while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors(DBRs) and confinement radius of 2.5 mm can realize the minimum temperature.展开更多
文摘可擦写型双层相变光盘的前记录层(激光入射面的记录层,或称前层)需要一个相变光记录层。该记录层具有高投射率的反射率反差[设结晶部的反射率为Rcry、非结晶部的反射率为Ramo,则反射率反差的定义为(Rcry-Ramo)/(Rcry+Ramo)]。从激光入射面来看,该前层的结构依次是ZnS-SiO_2层、界面层、GeTe-Sb_2Te_3相变材料层(6nm)、界面层、Ag合金反射层(10nm)。和传统的结构相比,其特点是最上层为具有稿投射率的TiO_2层(20nm)。TiO_2层与反射层之间可产生光学干涉,非晶部和结晶部可实现高投射率,分别达到54％和51％。而且,为了增大反射率反差,采用使信号极性成为Rcry>Ramo的所谓“High to Low结构”,获得了超过0.7的巨大的反射率反差(Ramo=0.7％,Rcry=5.7％)。该前层采用波长405nm、NA=0.85的光学系统,记录最短标记(记录畴)长为0.149μm的1-7PP调制信号(双层相当于50GB的密度)时,在10mW的记录功率条件下,可获得7.4的抖晃值。
基金supported by the National Natural Science Foundation of China (Grant Nos. 10925421 and 10734130)
文摘A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incident plane.The results showed that it was linearly polarized.We established a surface current model to explain this phenomenon,assuming that the transient current moving along the plasma surface was responsible for the generation of the THz emission.The model expectation and the experimental result were in good agreement.
基金supported by the Natural Science Foundation of Hebei Province (No.F2007000096)the Research Foundation for the Doctoral Program of Higher Education of China (No.20070080001)
文摘The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold characteristics of VCSELs with various proton implanted depths are studied after optical,electrical and thermal fields have been simulated self-consistently in three dimensions.It is found that for VCSELs with confinement radius of 2 mm,increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region.Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs.The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 mm,while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors(DBRs) and confinement radius of 2.5 mm can realize the minimum temperature.
