Photonic generation of high-frequency microwaves using two mutually coupled semiconductor lasers

Chin-Hao Tseng^1*, Wei-Ting Chien¹, Bin-Kai Liao¹, 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

High-frequency microwave generation with high spectral purity plays essential roles in many contemporary applications, including high-resolution radar and high-speed wireless communication. Over the past decades, photonic microwave generation has attracted much research interest since they offer many attractive advantages compared to electronic counterparts, such as simplicity of high-frequency generation, ease of wide frequency tunability, and low transmission loss. Recently, period-one nonlinear dynamics excited by a semiconductor laser subject to continuous-wave optical injection has been studied for microwave generation due to the continuous and broad-band frequency tunability. Microwave generation from tens to hundreds of gigahertz can be obtained without the limitation of electronic device bandwidth. However, due to the intrinsic spontaneous emission noise of semiconductor lasers, the 3-dB linewidth of the photo-detected microwaves is typically on the order of 0.1 to 10 MHz, limiting the scope of practical applications. A few all-optical stabilization techniques have been introduced to improve the phase quality of the generated microwaves. We propose a novel photonic approach for microwave generation and stabilization based on two mutually coupled semiconductor lasers with highly asymmetric coupling strength. As a result, a 101.2-GHz microwave with a 3-dB linewidth below 2 kHz and a side-peak-suppression ratio of 47 dB is achieved.

Keywords: Period-one nonlinear dynamics, Semiconductor lasers, Linewidth narrowing, Phase noise reduction, High-frequency microwave