Nonlinear Dynamics of Semiconductor Lasers for Photonic Microwave Time Delays
Kun-Lin Hsieh1*, Sheng-Kwang Hwang1,2, Chin-Lung Yang3
1Department of Photonics, National Cheng Kung University, Tainan, Taiwan
2Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan
3Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan
* presenting author:Kun-Lin Hsieh,
Microwave time delays have attracted much research interest for antenna remoting applications, such as wireless communication systems adopting phase-arrayed antennas. Photonic approaches provide various promising advantages over electronic ones, including broad bandwidth, high re-configurability and flexibility, immunity to electromagnetic interference, and high capability to process multiple beams. In this study, photonic microwave time delays using nonlinear dynamics of semiconductor lasers is proposed. While the optical injection regenerates, oscillation sidebands that are equally separated from the regeneration by a frequency ranging from a few gigahertz to tens or even hundreds of gigahertz emerge. Owing to the cavity resonance red-shift, nonlinear dynamics of semiconductor lasers have attracted much research interest for various signal processing functionalities. This study takes advantage of the optical phase changes around the oscillation sidebands of the P1 dynamics for microwave time delays. In this study, a microwave at 40 GHz has been demonstrated successfully for 158-ps time delay with a broad bandwidth of 4 GHz. Only 2.3o phase error between experimental data and the linear fitting curve is observed. For the microwave after passing through the proposed system, not only the 3-dB linewidth but also the phase noise is mainly preserved. Based on the simulation, it is found that the level of the microwave time delay actually depends on the injection strength. A 90-ps tunable range of time delay can be achieved experimentally with phase errors below 6o, which is able to confined beam squint within 2o in a phased-array antenna system. In the proposed system, the operated microwave frequency can be controlled by adjusting the injection conditions from 24 GHz to 40 GHz. It can be further enhanced up to 100 GHz by increasing the bias current or even adopting other lasers with higher relaxation resonance frequency at free running.

* S.K. Hwang’s work is supported by the Ministry of Science and Technology of Taiwan under Contract MOST103-2112-M-006-013-MY3, and the Asian Office of Aerospace Research and Development of the U.S. Air Force under Grant FA2386-15-1-4026.

Keywords: Nonlinear Dynamics, Semiconductor Laser, Photonic Microwave, Time Delay