光电负反馈下1550nm垂直腔表面发射激光器的动力学特性

基于激光输出的时间序列、功率谱以及相图,对1 550 nm垂直腔表面发射激光器(1 550 nmVCSELs)在光电负反馈作用下的动力学特性进行了研究.结果表明:固定偏置电流,在不同反馈强度下,光电负反馈1 550 nm VCSEL可呈现规则脉冲态、准周期态、混沌脉冲态等非线性动力学态;固定反馈强度,偏置电流取不同值时.1 550 nm-VCSEL也可呈现脉冲态、准周期态、混沌脉冲态等不同的非线性动力学状态.给出了1 550 nm VCSEL非线性动力学状态在偏置电流和反馈强度构成的参量空间分布.分析了激光器的动态演化路径,结果表明:在较小偏置电流和弱光电反馈下,激光器主要工作在稳态:随着偏置电流增加,激光器输出的动力学态通常随反馈强度的增加以规则脉冲态-准周期态-规则脉冲态的方式循环演化到混沌脉冲态;当偏置电流增加到一定值后,激光器输出的动力学态随反馈强度的增加主要以规则脉冲态准周期态混沌脉冲态的方式循环演化.

Design of a 12-Gbit/s CMOS DNFFCG differential transimpedance amplifier

A 12-Gbit/s low-power,wide-bandwidh CMOS(complementary metal oxide semiconductor)dual negative feedback feed-forward common gate(DNFFCG)differential trans-impedance amplifier(TIA)is presented for the veryshort-reach(VSR)optoelectronic integrated circuit(OEIC)receiver.The dominant pole of the input node is shifted up to a high frequency,and thus the bandwidth of the CMOS DNFFCG TIA is improved.Besides,two negative feedback loops are used to reduce the input impedance and further increase the bandwidth.The proposed TIA was fabricated using TSMC 0.18 jxm CMOS technology.The whole circuit has a compact chip area,the core area of which is only 0.003 6 mm2.The power consumption is 14.6 mW excluding 2-stage differential buffers.The test results indicate that the 3 dB bandwidth of 9 GHz is achieved with a 1 8 V supply voltage and its trans-impedance gain is 49.2 dBH.The measured average equivalent input noise current density is 28.1 pA H z12.Under the same process conditions,the DNFFCG has better gain bandwidth product compared with those in the published papers.