Introduction
The capability of identifying the frequency of unknown intercepted microwave signals is highly desirable in modern electronic countermeasure, radar warning and electronic intelligence systems. Photonic-assisted microwave measurements with distinct features such as large bandwidth, low loss, low power consumption and immunity to electromagnetic interference, have been extensively explored. Current methods are basically based on frequency-to-power mapping or frequency-to-time mapping, which can either realize instantaneous measurement of single frequency or multiple frequency measurement. However, for real-world operations, it remains a challenge whether we can identify different types of microwave signals simultaneously and identify the frequency varying instantaneously in a single photonic circuit. In addition, previous photonic-assisted solutions were either based on discrete components or partially integrated, practical applications also require system stability and compactness.
Recently, the team of Prof. Xinliang Zhang and Prof. Jianji Dong from Huazhong University of Science and Technology proposed a new method for microwave frequency measurement based on a dual-modality system. The system is highly integrated on the silicon-on-insulator (SOI) platform. Experimental results successfully demonstrated the ability to identify multiple frequencies and instantaneous measurement as well. The related work, titled Highly integrated dual-modality microwave frequency identification system, was published online on Laser & Photonics Reviews on July 19.
Research Highlights
Figure 1. Highly integrated dual-modality microwave frequency identification chip.
To solve the above-mentioned problems, as shown in Fig. 1, the novel frequency measurement system proposed in this study has two modalities. Through modality I, the system is able to identify different types of microwave signals, including single frequency, multiple frequency, chirped frequency and frequency hopping signals based on frequency-to-time mapping. It can also discriminate instantaneous frequency variation among the frequency-modulated signals based on frequency-to-power mapping through modality II, providing the system with the most powerful and comprehensive functionalities to date. In addition, the system is highly integrated on the SOI platform (including a modulator, a sweeping-frequency filter, a frequency-selected filter, an amplitude comparison function, and photodetectors). Thus, our chip integrates the key components of the microwave frequency measurement system with a small size (3.8 mm×2.2 mm), light weight (6g) and low power consumption (3.52W). The successful demonstration of this system has important impact for the further development of general integrated microwave photonic systems.
Figure 2. Measurement results of chirped frequency signals and frequency-hopping signals through modality I.
Figure 3. Measurement results of dynamic frequency identification through modality II.
Conclusion and Outlook
Based on the dual-modality approach, this work shows that the system has the ability of multiple frequency measurement and instantaneous frequency measurement. It has the advantages of high integration level, real-time performance, small size, weight, and low power consumption. It is promising to be applied to future advanced miniature microwave photonic systems.
This work is supported by the National Key Research and Development Project of China, the National Natural Science Foundation of China, and the Innovation Project of Optics Valley Laboratory. Prof. Jianji Dong is the corresponding author, and Yuhan Yao is the first author. Microwave frequency measurement is one of the research areas that our group has been focusing on. In recent years, several solutions based on semiconductor optical amplifier and microring have been proposed. The relevant researches have been published on Chinese Optics Letters 9, 051202 (2011), IEEE Photonics Journal 10, 5500807 (2018), Photonics Research 7, 172-181 (2019), Laser & Photonics Reviews 2200006 (2022).
Paper information
Y. Yao, Y. Zhao, Y. Wei, F. Zhou, D. Chen, Y. Zhang, X. Xiao, M. Li, J. Dong, S. Yu, and X. Zhang, "Highly Integrated Dual-Modality Microwave Frequency Identification System," Laser & Photonics Reviews 2200006 (2022).
Full text can be viewed at: https://doi.org/10.1002/lpor.202200006
