Improvement of bandwidth of phase-locked loop for mode-locked laser with multiple-differentials-based loop filter

Area of Science:

• Optics and Photonics
• Control Systems Engineering

Background:

• Mode-locked lasers are crucial for high-speed optical applications.
• Phase-locked loops (PLLs) are essential for stabilizing laser frequencies.
• Existing PLLs often have limited bandwidth, restricting laser performance.

Purpose of the Study:

• To propose and validate a new scheme for enhancing the bandwidth of PLLs used in mode-locked lasers.
• To improve the upper-limit bandwidth of laser-based PLL systems.

Main Methods:

• Implementation of a modified PLL incorporating a multiple-differentials-based loop filter.
• Detailed theoretical explanation of the bandwidth improvement mechanism.
• Experimental validation of the proposed scheme in a laser-based PLL.

Main Results:

• The proposed scheme successfully increased the upper-limit bandwidth of the laser-based PLL.
• Bandwidth enhancement by approximately one order of magnitude was achieved.
• Improvement was observed at offset frequencies ranging from 3 kHz to 30 kHz.

Conclusions:

• The developed multiple-differentials-based loop filter effectively enhances PLL bandwidth for mode-locked lasers.
• The proposed scheme offers a simple and adaptable solution for improving laser phase-locking systems.
• This technique has broad applicability in laser systems requiring enhanced bandwidth performance.