Researchers from the University of Southern California, led by Professor Zaijun Chen and Mengjie Yu, have made significant strides in mid-infrared (MIR) light modulation, a technology with potential applications in remote sensing, precision spectroscopy, and free-space optical communication. The team has developed a suspended thin-film lithium niobate (TFLN) based electro-optic (EO) platform that addresses key challenges in the field.
The MIR spectral regime is crucial for various applications, but coherent and broadband MIR modulation has been hindered by high optical loss, limited bandwidth, and large drive voltages in existing platforms. The researchers overcame these challenges by deploying a suspended TFLN platform co-designed with high-performance traveling-wave microwave (MW) electrodes. This innovation resulted in a record-low Vpi,DC of 2.3 to 4.3 V over a broadband MIR bandwidth from 2.4 to 3.6 micrometers, and a 2.7 dB EO bandwidth of 40 GHz (extracted 3 dB bandwidth of 50 GHz). The figure of merit achieved was 17.4 GHz/V, more than an order of magnitude higher than the state of the art.
The team also demonstrated, for the first time, high-frequency Vpi,MW of 4.5 to 6.5 V in the 25 to 35 GHz range, and frequency-agile MIR EO frequency comb generation with a 10 dB optical bandwidth over 0.8 THz using a suspended phase modulator of 4 cm active modulation length. These achievements were validated in a free-space optical communication link, establishing a monolithic MIR photonic platform capable of powerful EO modulation and spectral synthesis.
The practical applications of this research for the energy sector include improved remote sensing capabilities for monitoring environmental impacts of energy production and distribution, enhanced precision spectroscopy for detecting and measuring greenhouse gases and other pollutants, and more efficient free-space optical communication for data transmission in renewable energy systems. The research was published in the journal Nature Communications.
This article is based on research available at arXiv.