Green-diode-pumped femtosecond Ti:Sapphire laser with up to 450 mW average power.

K Gürel,K Weingarten,S Schilt,M Hoffmann,T Südmeyer,V J Wittwer,C J Saraceno,S Hakobyan,A Rohrbacher,B Resan

doi:10.1364/oe.23.030043

Abstract

We investigate power-scaling of green-diode-pumped Ti:Sapphire lasers in continuous-wave (CW) and mode-locked operation. In a first configuration with a total pump power of up to 2 W incident onto the crystal, we achieved a CW power of up to 440 mW and self-starting mode-locking with up to 200 mW average power in 68-fs pulses using semiconductor saturable absorber mirror (SESAM) as saturable absorber. In a second configuration with up to 3 W of pump power incident onto the crystal, we achieved up to 650 mW in CW operation and up to 450 mW in 58-fs pulses using Kerr-lens mode-locking (KLM). The shortest pulse duration was 39 fs, which was achieved at 350 mW average power using KLM. The mode-locked laser generates a pulse train at repetition rates around 400 MHz. No complex cooling system is required: neither the SESAM nor the Ti:Sapphire crystal is actively cooled, only air cooling is applied to the pump diodes using a small fan. Because of mass production for laser displays, we expect that prices for green laser diodes will become very favorable in the near future, opening the door for low-cost Ti:Sapphire lasers. This will be highly attractive for potential mass applications such as biomedical imaging and sensing.

Highlights

Thirty years after their invention, Ti:Sapphire lasers remain widely used in industry and research [1]
Pumping in the blue-green spectral region is mandatory, which was initially done by Ar:ion lasers and frequency-doubled diode-pumped solid-state lasers (DPSSLs), and in the last years by frequency-doubled vertical externalcavity surface-emitting lasers (VECSELs) [10]
We demonstrated the highest power from any diode-pumped Ti:Sapphire solid-state laser, achieving 650 mW power in CW and 450 mW of average power in mode-locked operation with 58 fs pulses

Summary

Introduction

Thirty years after their invention, Ti:Sapphire lasers remain widely used in industry and research [1]. The demonstration of the first directly green-pumped Ti:Sapphire DPSSL followed: Sawai et al achieved 23.5 mW of average power in 62-fs pulses using a 1-W laser diode at 520 nm, and a SESAM for mode-locking [20], corresponding to an optical-to-optical efficiency of

Experiment

Results

Conclusion