Photonic Generation of High-Frequency Microwave Chaos Using Optically Injected Semiconductor Lasers

Chin-Hao Tseng^1*, Sheng-Kwang Hwang^1,2

¹Department of Photonics, National Cheng Kung University, Tainan, Taiwan
²Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan

* Presenter:Chin-Hao Tseng, email:purep228@gmail.com

Radar systems with high detection capability are required for civilian and military applications, such as automobile collision avoidance systems and through-the-wall imaging. Linearly chirped microwaves and microwave chaos have been proposed to improve the detection capability of radar systems through pulse compression. Linearly chirped microwaves, however, suffer from serious range-Doppler coupling, which reduces their Doppler resolution. Microwave chaos, on the other hand, has a noise-like waveform, which increases its range resolution and Doppler resolution simultaneously. However, it is difficult to generate microwave chaos at a high frequency with a broad bandwidth using only electronic devices. Owing to the inherent nature of photonic devices, generation of broadband microwave chaos at a baseband using semiconductor lasers has lately been demonstrated to improve detection capability of radar systems. In this study, a novel photonic scheme is proposed to generate broadband microwave chaos at a high frequency using a semiconductor laser subject to external optical injection. The underlying mechanism of the system relies solely on the nonlinear laser characteristics, and therefore only a typical semiconductor laser is necessary. Microwave chaos generation at high frequency with a broad bandwidth and a flat spectrum is obtained.

Keywords: semiconductor lasers, radar, microwave photonics, chaos, optical injection