Carrier-envelope offset locking with a 2f-to-3f self-referencing interferometer using a dual-pitch PPLN ridge...

Area of Science:

• * Optics and Photonics
• * Laser Physics
• * Nonlinear Optics

Background:

• * Stabilizing the carrier-envelope offset frequency (f CEO) is critical for advancing optical frequency comb technology.
• * Er-doped fiber lasers present unique challenges for f CEO stabilization due to spectral limitations.
• * Traditional methods often require a broad supercontinuum spectrum, which is difficult to generate in some laser systems.

Purpose of the Study:

• * To demonstrate the efficacy of a 2f-to-3f self-referencing interferometer (SRI) for f CEO stabilization in Er-doped fiber lasers.
• * To develop a compact and efficient method for generating the necessary nonlinear optical signals.
• * To achieve high-precision f CEO stabilization without requiring a one-octave supercontinuum.

Main Methods:

• * Employed a dual-pitch periodically poled lithium niobate (PPLN) ridge waveguide to efficiently generate third-harmonic light.
• * Utilized a 2f-to-3f SRI configuration to create a self-referencing beat signal for f CEO detection.
• * Integrated the SRI with an Er-doped fiber laser system for closed-loop frequency stabilization.

Main Results:

• * Achieved a high signal-to-noise ratio of 45 dB in a 100-kHz bandwidth for the heterodyne beat signal.
• * Demonstrated an in-loop f CEO instability of 8 × 10⁻¹⁸ at 1 second averaging time.
• * Successfully stabilized the f CEO without the need for a supercontinuum spectrum.

Conclusions:

• * The 2f-to-3f SRI is a powerful and practical tool for f CEO stabilization of Er-doped fiber lasers.
• * The dual-pitch PPLN waveguide enables efficient third-harmonic generation, simplifying the stabilization setup.
• * This technique offers a viable solution for f CEO stabilization in systems where generating a wide spectrum is challenging, paving the way for more robust frequency combs.