Scientists have recently made a significant advancement in optics by creating cutting-edge technology that promises to revolutionize how electronic signals are processed and transmitted.

(Photo: Wikimedia Commons/ FMNLab)


Challenges in Analog Signal Processing

Due to the rapid expansion of the Internet of Things, wireless networks, and cloud-based services, there have been significant demands on underlying radio frequency systems. Microwave photonics (MWP) technology offers effective solutions to these challenges.

Microwave photonics refers to an interdisciplinary research between radio-frequency engineering and photo-electronics. It uses optical components to generate, transmit, and manipulate microwave signals.

This technology imposes a radio-frequency input signal in an optical signal using an external electro-optic modulator. Then, the signal is optically processed through photonic devices and is emitted through a photo receiver as radio frequency output.

Despite their benefits, integrated microwave photonics systems struggle to achieve ultrahigh-speed analog signal processing with high fidelity, chip-scale integration, and low power. An ideal integrated microwave photonics processing platform should have an efficient and high-speed electro-optic modulation block. Additionally, it should achieve large-scale, low-cost manufacturability to integrate two building blocks on the same chip monolithically.


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World-Leading MW Photonics Chip

Addressing this problem has been the goal of researchers from the City University of Hong Kong (CityUHK). Led by Professor Wang Cheng from the Department of Electrical Engineering (EE), the experts have developed a world-leading microwave photonic chip. The details of their study are discussed in the paper "Integrated lithium niobate microwave photonic processing engine."

The chip is 1,000 times faster and consumes less energy than a traditional electronic processor. The newly developed microwave photonics systems combine ultrafast electro-optic (EO) conversion with low-loss, multifunctional signal processing on a single integrated chip. This technology has not been achieved before.

Such capabilities were made possible by an integrated microwave photonics processing engine based on a thin-film lithium niobate (LN) platform. This platform can perform multi-purpose processing and compute analog signal tasks.

According to research first author Feng Hanke, the chip can carry out high-speed analog computation with ultrabroad processing bandwidths of 67 GHz and outstanding computation accuracies. Due to its performance, the chip can have many applications, such as high-resolution radar systems, 5/6 G wireless communication systems, computer vision, artificial intelligence, and image/video processing.

The research team has been dedicating their lives to developing the integrated lithium niobate photonic platform for several years. In 2018, scientists at Harvard University and Nokia Bell laboratories collaborated to create the world's first complementary metal-oxide semiconductor (CMOS).

The material laid the foundation for the current research breakthrough, providing compatible integrated electro-optic modulators on the lithium niobate platform. Lithium niobate is comparable to silicon in microelectronics, even referred to as the "silicon of photonics" due to its importance to the field.

The research also opens up a new field, such as lithium niobate microwave photonics. This technology enables the development of microwave photonic chips with high signal fidelity, compact sizes, and low latency. It also represents analog electronic processing and computing engines at chip scale.

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