We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band.Our theoretical considerations ...We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band.Our theoretical considerations are verified by numerical simulations performed on different dielectric mirror structures.The revealed proportionality between group delay and absorbed energy sets constraint on the application of ultrabroadband and/or dispersive dielectric mirrors in broadband or widely tunable,high-power laser systems.展开更多
A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the l...A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm.展开更多
To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd...To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd order optical sideband and local oscillator(LO) signal on-3 rd order sideband using the intermodulation process in the DPMZM. After suppressing of the optical carrier and other sidebands through proper adjustment for modulator biases and modulation index, a frequency sextupled millimeter-wave vector signal can be generated after photodetection. The frequency sextupling will lower the bandwidth of the modulator, the local oscillator and the driving circuits. In addition, the phase of generated signal is not distorted after detection, and the power fading after fiber transmission can be avoided. In the simulation, a 500-MSym/s QPSK signal at 60 GHz is generated by 10-GHz drive signal. After travelling over fiber with length of 20/30/40-km, receiver power penalty keeps below 2.5 dB.展开更多
基于DPMZM和两个电移相器,文中给出了一种具有高交调抑制比的倍频信号产生及模拟信号传输方法,该方法可广泛应用于ROF系统中。通过调整DPMZM的直流偏置工作点和电移相器相位,可生成高交调失真抑制比的倍频信号。基于同一结构,仅调整DPMZ...基于DPMZM和两个电移相器,文中给出了一种具有高交调抑制比的倍频信号产生及模拟信号传输方法,该方法可广泛应用于ROF系统中。通过调整DPMZM的直流偏置工作点和电移相器相位,可生成高交调失真抑制比的倍频信号。基于同一结构,仅调整DPMZM中一个子调制器的直流工作点就可以实现高线性模拟信号传输。实验结果表明,所生成的倍频信号的交调失真比可达30 d B以上;所构建的高线性模拟信号传输链路可完全抑制三阶交调失真分量。该方法在降低ROF系统难度和复杂度的同时,大大提高了系统稳定性。实验结果与理论分析结果相吻合。展开更多
基金supported in part by the National "973" Program of China (No. 2011CB301702)the National Natural Science Foundation of China (Nos. 61001121,61006041,60736036,and 60932004)the Fundamental Research Funds for the Central Universities
文摘We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band.Our theoretical considerations are verified by numerical simulations performed on different dielectric mirror structures.The revealed proportionality between group delay and absorbed energy sets constraint on the application of ultrabroadband and/or dispersive dielectric mirrors in broadband or widely tunable,high-power laser systems.
基金the National Natural Science Foundation of China under Grants No.61927821 and No.61575037.
文摘A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm.
基金Sponsored by the Programme of Introducing Talents of Discipline to Universities(Grant No.B08038)
文摘To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd order optical sideband and local oscillator(LO) signal on-3 rd order sideband using the intermodulation process in the DPMZM. After suppressing of the optical carrier and other sidebands through proper adjustment for modulator biases and modulation index, a frequency sextupled millimeter-wave vector signal can be generated after photodetection. The frequency sextupling will lower the bandwidth of the modulator, the local oscillator and the driving circuits. In addition, the phase of generated signal is not distorted after detection, and the power fading after fiber transmission can be avoided. In the simulation, a 500-MSym/s QPSK signal at 60 GHz is generated by 10-GHz drive signal. After travelling over fiber with length of 20/30/40-km, receiver power penalty keeps below 2.5 dB.
文摘基于DPMZM和两个电移相器,文中给出了一种具有高交调抑制比的倍频信号产生及模拟信号传输方法,该方法可广泛应用于ROF系统中。通过调整DPMZM的直流偏置工作点和电移相器相位,可生成高交调失真抑制比的倍频信号。基于同一结构,仅调整DPMZM中一个子调制器的直流工作点就可以实现高线性模拟信号传输。实验结果表明,所生成的倍频信号的交调失真比可达30 d B以上;所构建的高线性模拟信号传输链路可完全抑制三阶交调失真分量。该方法在降低ROF系统难度和复杂度的同时,大大提高了系统稳定性。实验结果与理论分析结果相吻合。
