Terahertz wave generation using a soliton microcomb.

Area of Science:

• Physics
• Electrical Engineering
• Optics

Background:

• Terahertz (THz) waves (300 GHz - 3 THz) bridge microwaves and infrared light, offering potential for broadband wireless communications, remote sensing, and imaging.
• Optically generated THz waves are crucial for low-noise signal generation, driving research in advanced applications.

Purpose of the Study:

• To propose and demonstrate stabilized terahertz wave generation using a microresonator-based frequency comb (microcomb).
• To achieve high stability and low phase noise in optically generated THz signals for practical applications.

Main Methods:

• Utilized a microcomb to generate low-noise optical soliton pulses.
• Employed a unitravelling-carrier photodiode (UTC-PD) to convert optical pulses to THz waves at the soliton's repetition rate (331 GHz).
• Locked the microcomb's repetition rate to a hydrogen maser to enhance frequency stability.

Main Results:

• Achieved a fractional frequency stability of 9.6×10^-15 at 1 s and 1.9×10^-17 at 2000 s after locking to the maser.
• Demonstrated proof-of-principle terahertz imaging of peanuts.
• Reported phase noise of -72 dBc/Hz at 10 kHz and -118 dBc/Hz at 10 MHz offset frequency for the free-running microcomb.

Conclusions:

• The microcomb-based THz generation technique offers a pathway to highly stable, chip-scale THz sources.
• This technology is suitable for out-of-the-lab applications including high-capacity wireless communication, spectroscopy, imaging, and remote sensing.