Intra-cavity gain shaping of mode-locked Ti:Sapphire laser oscillations

TL;DR

This paper demonstrates precise control over mode competition in a Ti:sapphire laser by spectral gain shaping, enabling stable two-color oscillations that are inaccessible with purely homogeneous gain.

Contribution

It introduces a method to manipulate gain properties in a mode-locked laser to selectively stabilize otherwise unstable multi-color oscillations.

Findings

Selective enhancement of two-color oscillation via spectral gain shaping

Flexible control over wavelength, intensity, and bandwidth of the two colors

Stable two-color operation achieved in a regime previously inaccessible

Abstract

The gain properties of an oscillator strongly affect its behavior. When the gain is homogeneous, different modes compete for gain resources in a `winner takes all' manner, whereas with inhomogeneous gain, modes can coexist if they utilize different gain resources. We demonstrate precise control over the mode competition in a mode locked Ti:sapphire oscillator by manipulation and spectral shaping of the gain properties, thus steering the competition towards a desired, otherwise inaccessible, oscillation. Specifically, by adding a small amount of spectrally shaped inhomogeneous gain to the standard homogeneous gain oscillator, we selectively enhance a desired two-color oscillation, which is inherently unstable to mode competition and could not exist in a purely homogeneous gain oscillator. By tuning the parameters of the additional inhomogeneous gain we flexibly control the center wavelengths, relative intensities and widths of the two colors.