下一代数字用户线(NG-DSL,Next Generation Digital Subscriber Line)技术使用高载波数与高正交振幅的OFDM调制方式,这对信号同步提出了更高的要求.提出了一种新的基于数据辅助型的符号定时算法——基于最小能量差的符号定时同步算法....下一代数字用户线(NG-DSL,Next Generation Digital Subscriber Line)技术使用高载波数与高正交振幅的OFDM调制方式,这对信号同步提出了更高的要求.提出了一种新的基于数据辅助型的符号定时算法——基于最小能量差的符号定时同步算法.该算法通过变步长搜索的方法,利用较少的步骤准确快速搜索到最小值,大大降低算法复杂度,最后对算法进行综合性能比较,仿真结果表明,新算法具有复杂度低,在NG-DSL环境下定时准确并且具有抗双绞线信道拖尾干扰能力强的特点,这些特点能够较好地满足NG-DSL对于符号定时同步算法的要求.展开更多
To improve the optical and electrical properties of AlGaN-based deep ultraviolet lasers,an inverse-trapezoidal electron blocking layer is designed.Lasers with three different structural electron blocking layers of rec...To improve the optical and electrical properties of AlGaN-based deep ultraviolet lasers,an inverse-trapezoidal electron blocking layer is designed.Lasers with three different structural electron blocking layers of rectangular,trapezoidal and inverse-trapezoidal structures are established.The energy band,electron concentration,electron current density,P-I and V-I characteristics,and the photoelectric conversion efficiency of different structural devices are investigated by simulation.The results show that the optical and electrical properties of the inversetrapezoidal electron blocking layer laser are better than those of rectangular and trapezoidal structures,owing to the effectively suppressed electron leakage.展开更多
An AlGaN-based deep ultraviolet laser diode with convex quantum wells structure is proposed. The advantage of using a convex quantum wells structure is that the radiation recombination is significantly improved. The i...An AlGaN-based deep ultraviolet laser diode with convex quantum wells structure is proposed. The advantage of using a convex quantum wells structure is that the radiation recombination is significantly improved. The improvement is attributed to the increase of the effective barrier height for electrons and the reduction of the effective barrier height for holes, which results in an increased hole injection efficiency and a decreased electron leakage into the p-type region. Particularly, comparisons with the convex quantum barriers structure and the reference structure show that the convex quantum wells structure has the best performance in all respects.展开更多
文摘下一代数字用户线(NG-DSL,Next Generation Digital Subscriber Line)技术使用高载波数与高正交振幅的OFDM调制方式,这对信号同步提出了更高的要求.提出了一种新的基于数据辅助型的符号定时算法——基于最小能量差的符号定时同步算法.该算法通过变步长搜索的方法,利用较少的步骤准确快速搜索到最小值,大大降低算法复杂度,最后对算法进行综合性能比较,仿真结果表明,新算法具有复杂度低,在NG-DSL环境下定时准确并且具有抗双绞线信道拖尾干扰能力强的特点,这些特点能够较好地满足NG-DSL对于符号定时同步算法的要求.
基金the National Natural Science Foundation of China under Grant No.61176008the Special Project for Intergovernment Collaboration of State Key Research and Development Program under Grant No.2016YFE0118400+1 种基金the Key Project of Science and Technology of Henan Province under Grant No.172102410062the National Natural Science Foundation of China-Henan Provincial Joint Fund for Key Project under Grant No.U1604263.
文摘To improve the optical and electrical properties of AlGaN-based deep ultraviolet lasers,an inverse-trapezoidal electron blocking layer is designed.Lasers with three different structural electron blocking layers of rectangular,trapezoidal and inverse-trapezoidal structures are established.The energy band,electron concentration,electron current density,P-I and V-I characteristics,and the photoelectric conversion efficiency of different structural devices are investigated by simulation.The results show that the optical and electrical properties of the inversetrapezoidal electron blocking layer laser are better than those of rectangular and trapezoidal structures,owing to the effectively suppressed electron leakage.
基金This work has been supported by the National Natural Science Foundation of China(No.61176008)the Special Project for Inter-government Collaboration of State Key Research and Development Program(No.2016YFE0118400)+1 种基金the Key Project of Science and Technology of Henan Province(No.172102410062)the National Natural Science Foundation of China Henan Provincial Joint Fund Key Project(No.U1604263).
文摘An AlGaN-based deep ultraviolet laser diode with convex quantum wells structure is proposed. The advantage of using a convex quantum wells structure is that the radiation recombination is significantly improved. The improvement is attributed to the increase of the effective barrier height for electrons and the reduction of the effective barrier height for holes, which results in an increased hole injection efficiency and a decreased electron leakage into the p-type region. Particularly, comparisons with the convex quantum barriers structure and the reference structure show that the convex quantum wells structure has the best performance in all respects.
