Chen Yang, Liu Shifeng, Pan Shilong
Opt Express. 2018 Feb 5;26(3):3404-3420. doi: 10.1364/OE.26.003404.
A novel photonic approach for multi-format signal generation based on a frequency-tunable optoelectronic oscillator (OEO) is proposed using a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator. The upper dual-parallel Mach-Zehnder modulator (DP-MZM) integrated in the DP-QPSK modulator is properly biased to serve as an equivalent phase modulator, which functions in conjunction with a phase-shifted fiber Bragg grating (PS-FBG) in the OEO loop as a high-Q microwave photonic band-pass filter. The lower DP-MZM in the DP-QPSK modulator injected by the oscillation signal functions as a frequency multiplier, a phase-coded microwave signal generator or an optical frequency comb generator, respectively, with different signal injection methods. An experiment is performed. When the lower DP-MZM serves as a frequency multiplier, tunable frequency-doubled and quadrupled microwave signals up to 40 GHz are generated without using an optical notch filter; and if it functions as a phase-coded microwave signal generator, fundamental and frequency-doubled binary phase-coded microwave signals are generated with a tunable frequency. Furthermore, tunable five-line optical frequency combs are also generated using the compact system without an external RF source. The performance of the generated signals is also investigated.
提出了一种基于频率可调谐光电振荡器（OEO）的用于多格式信号生成的新型光子方法，该方法使用双偏振正交相移键控（DP-QPSK）调制器。集成在DP-QPSK调制器中的上部双平行马赫-曾德尔调制器（DP-MZM）被适当偏置以用作等效相位调制器，它与OEO环路中的相移光纤布拉格光栅（PS-FBG）一起作为高Q微波光子带通滤波器发挥作用。DP-QPSK调制器中由振荡信号注入的下部DP-MZM分别通过不同的信号注入方法用作倍频器、相位编码微波信号发生器或光学频率梳发生器。进行了一项实验。当下部DP-MZM用作倍频器时，无需使用光陷波滤波器即可生成高达40 GHz的可调谐倍频和四倍频微波信号；如果它用作相位编码微波信号发生器，则会生成具有可调频率的基波和倍频二进制相位编码微波信号。此外，还使用该紧凑型系统在没有外部射频源的情况下生成了可调谐五线光学频率梳。还研究了所生成信号的性能。
