High-power femtosecond pulses without a modelocked laser.

Walter Fu,Logan G Wright,Frank W Wise

doi:10.1364/optica.4.000831

Abstract

We demonstrate a fiber system which amplifies and compresses pulses from a gain-switched diode. A Mamyshev regenerator shortens the pulses and improves their coherence, enabling subsequent amplification by parabolic pre-shaping. As a result, we are able to control nonlinear effects and generate nearly transform-limited, 140-fs pulses with 13-MW peak power-an order-of-magnitude improvement over previous gain-switched diode sources. Seeding with a gain-switched diode results in random fluctuations of 2% in the pulse energy, which future work using known techniques may ameliorate. Further development may allow such systems to compete directly with sources based on modelocked oscillators in some applications while enjoying unparalleled robustness and repetition rate control.

Highlights

Fiber lasers are becoming increasingly widespread in scientific and industrial settings
Maintaining stable modelocking in the face of environmental perturbations is an ongoing engineering problem. From this issue, modelocked oscillators are constrained to operate at their fundamental repetition rate. This loss of flexibility can be limiting for applications where pulses must be synchronized with scanning optics or other components, or where both average and peak power need to be optimized in tandem
Subsequent amplification in the normally-dispersive regime permitted pulse compression to 0.6 ps with peak powers exceeding 1 MW. This represented a new record for Gain-switched diodes (GSDs), the pulses remain too long for many ultrafast applications, and their large deviation from the transformlimited duration (¿4x) indicates a lack of control over the pulse

Summary

Introduction

Fiber lasers are becoming increasingly widespread in scientific and industrial settings. We first use a Mamyshev regenerator to shape the pulses from the GSD, at once compressing them and improving their coherence. An optimized length of normally-dispersive, passive fiber is used to parabolically shape the pulse [18], which is amplified in the highly nonlinear regime.

Results

Conclusion