All-PM Divided Pulse Fiber Oscillator Mode-locked with the Optical Kerr-effect

TL;DR

This paper presents a novel Yb-doped fiber oscillator that employs coherent pulse division and recombination to enhance pulse energy and stability, leveraging the Kerr effect and polarization techniques.

Contribution

It introduces a new mode-locking mechanism using pulse division with YVO4 crystals, achieving higher pulse energy and reduced amplitude fluctuations.

Findings

Pulse energy increased from 89 pJ to over 400 pJ.

Amplitude fluctuations reduced by up to 9 dB.

Stable mode-locked operation achieved with pulse division.

Abstract

In this letter, we investigate a Yb-doped mode-locked fiber oscillator that uses coherent pulse division and recombination to avoid excessive nonlinear phase shifts. The mode-locking mechanism of the laser is based on the accumulation of a differential nonlinear phase between orthogonal polarization modes in the polarization-maintaining fiber segment. The inserted coherent pulse divider, based on YVO4-crystals rotated successively by 45{\deg}, enables stable and undistorted mode-locked steady-states. The output pulse energy is increased from 89 pJ in the non-divided operation by ~6.5 dB to more than 400 pJ with three divisions. Measurements of the amplitude-fluctuations reveal a simultaneous broadband reduction of up to ~9 dB in the frequency range from 10 kHz to 2MHz.