次谐波调制下光注入DFB-LD结构的可调谐光电振荡器

为实现具有高频谱纯度、低相位噪声的宽带可调谐微波信号生成，提出并通过实验验证了一种次谐波信号调制下光注入半导体激光器结构的光电振荡器，其原理为通过利用光注入半导体激光器的单周期（P1）振荡工作状态和波长选择放大特性实现可调微波信号生成，并进一步通过在光电振荡环路中引入次谐波信号调制对系统生成微波信号的频率稳定性、边模抑制比与频谱纯度进行优化。实验结果表明，文中方案提出的光电振荡器可以生成输出功率大于5 dBm，频率调谐范围为12~18 GHz的微波信号。同时，系统生成的微波信号的3 dB带宽为100 kHz，边模抑制比可达 51 dB，且信号在频偏量为100 Hz和10 kHz处的相位噪声分别为?78 dBc/Hz和?109 dBc/Hz。此外，光电振荡器生成微波信号的频率调谐范围只受系统中使用的各类光电器件工作带宽的限制，通过采用具有更大带宽的光电器件可以实现更高频率的微波信号生成。

Tunable optoelectronic oscillator based on optically injected distributed-feedback semiconductor laser diode under subharmonic microwave modulation

In order to obtain microwave signal with high spectral purity, low phase noise and flexible tunability, a novel approach to achieving a tunable optoelectronic oscillator (OEO) which was based on optically injected semiconductor laser and subharmonic microwave modulation for microwave signal generation was proposed and experimentally demonstrated. The fundamental concepts for realizing the OEO were based on the wavelength-selective ampli?cation effect and the period-one(P1) oscillation state of optically injected semiconductor laser. The frequency stability, side-mode-suppression ratio and spectral purity of the generated microwave signal could be optimized by introducing subharmonic microwave modulation via a phase modulator in the OEO loop. The experimental results show that the central frequency of the microwave signal generated by the proposed OEO could be tuned from 12 GHz to 18 GHz, and output power of the generated signal was more than 5 dBm. At the same time, the generated signal had a side-mode-suppression ratio of 51 dB and a 3 dB bandwidth of 100 kHz. Finally, the phase noise of the measured microwave signal could be optimized to ?78 dBc/Hz and ?109 dBc/Hz at 100 Hz and 10 kHz frequency offset by introducing subharmonic microwave modulation in the system, respectively. Furthermore, the tunable frequency range of the generated signal was restricted by the operating bandwidths of the optic-electronic devices which were utilized in the system. A higher frequency of the generated microwave signal could be achieved by using the devices with larger bandwidths in the OEO loop.