Simple and seamless broadband optical frequency comb generation using an InAs/InP quantum dot laser.

Area of Science:

• Photonics
• Laser Physics
• Optical Engineering

Background:

• Optical frequency combs (OFCs) are crucial for precise frequency measurements and optical signal generation.
• Existing OFC generators can be complex and costly, limiting their widespread adoption.
• Quantum dot (QD) lasers offer unique properties for mode-locking and comb generation.

Purpose of the Study:

• To propose and demonstrate a simple and seamless broadband optical frequency comb generator.
• To achieve ultra-low phase noise and quasi-tunable characteristics in the OFC.
• To combine the advantages of quantum dot lasers and Mach-Zehnder modulators for OFC generation.

Main Methods:

• Utilizing a Fabry-Perot quantum dot mode-locked laser.
• Employing a dual-driven Lithium Niobate (LiNbO3) Mach-Zehnder modulator.
• Driving the modulator with a low-power radio frequency (RF) signal.

Main Results:

• Demonstrated a 10-dB seamless bandwidth of 8.2 nm (1.02 THz).
• Generated OFCs with 62 and 40 comb lines at 16.56 GHz and 24.84 GHz frequency intervals, respectively.
• Achieved single-sideband phase noise as low as -112 dBc/Hz at a 10 kHz offset and RF linewidths of 251-263 Hz.

Conclusions:

• A simple, seamless, and ultra-low phase noise broadband OFC generator was successfully demonstrated.
• The proposed method using a QD laser and MZM modulator offers a quasi-tunable and easily obtainable solution.
• This technology has potential for applications in optical communications, spectroscopy, and metrology.