Generation of GHz line-spacing tunable optical frequency combs using Talbot effects

Area of Science:

• Photonics
• Optical Engineering
• Laser Physics

Background:

• Optical frequency combs (OFCs) are crucial for precise frequency measurements and optical signal generation.
• Existing methods for tuning OFC line spacing can be complex and limited in flexibility.
• Electro-optical (EO) techniques offer potential for advanced OFC generation and control.

Purpose of the Study:

• To demonstrate a novel method for generating tunable optical frequency combs (OFCs) with GHz line-spacing.
• To achieve arbitrary control over OFC line spacing using temporal and spectral Talbot effects.
• To theoretically model and experimentally validate the proposed OFC generation principle.

Main Methods:

• Utilized an electro-optical (EO) Talbot laser incorporating a dual-parallel Mach-Zehnder modulator (DPMZM) for carrier-suppressed single-sideband modulation.
• Employed a phase modulator (PM) to induce the spectral Talbot effect and compensate for the temporal Talbot effect within the laser loop.
• Developed a theoretical model to describe the principle of the OFC generator.

Main Results:

• Successfully demonstrated the generation of tunable OFCs with initial 2 GHz line spacing.
• Experimentally multiplied the OFC line spacing to 4 GHz, 6 GHz, 8 GHz, and 10 GHz.
• Achieved fractional multiplication of OFC line spacing (e.g., 3/4, 7/2) as confirmed by simulations.

Conclusions:

• The proposed EO Talbot laser and phase modulator system enables arbitrary control over OFC line spacing.
• This technique provides a flexible and effective method for generating tunable GHz line-spacing optical frequency combs.
• The findings have implications for advanced optical signal processing and metrology applications.