Er-fiber laser enabled, energy scalable femtosecond source tunable from 1.3 to 1.7 µm.

Hsiang-Yu Chung,Qian Cao,Wei Liu,Guoqing Chang,Franz X Kärtner

doi:10.1364/oe.25.015760

Hsiang-Yu Chung, Qian Cao + Show 3 more

Open Access

https://doi.org/10.1364/oe.25.015760

Copy DOI

Abstract

We demonstrate that energetic femtosecond pulses tunable from 1.3 to 1.7 µm can be achieved using self-phase modulation enabled spectral broadening followed by spectral lobe filtering. Based on a home-built 5-W Er-fiber laser system operating at 31-MHz repetition rate, we obtain femtosecond pulses that can be continuously tuned from 1.3 to 1.7 µm with >4.5 nJ pulse energy. We further optimize the spectral broadening process using a fiber with larger mode area and scale up the pulse energy to >10 nJ; the resulting pulse duration is as short as ~50 fs. Such a widely tunable, energetic femtosecond source is well suited for driving a laser scanning microscope to perform deep tissue multiphoton microscopy.

Highlights

Ultrafast sources emitting femtosecond pulses with the center wavelength continuously tunable are desired in many microscopy and spectroscopy applications
We demonstrate that energetic femtosecond pulses tunable from 1.3 to 1.7 μm can be achieved using self-phase modulation enabled spectral broadening followed by spectral lobe filtering
Numerical simulation of fiber-optic spectral broadening Before we present the experimental results, we first use numerical simulations to illustrate our method of implementing wavelength tunable femtosecond sources

Summary

Introduction

Ultrafast sources emitting femtosecond pulses with the center wavelength continuously tunable are desired in many microscopy and spectroscopy applications. We further optimize the spectral broadening process using a fiber with larger mode area and scale up the pulse energy to >10 nJ; the resulting pulse duration is as short as ~50 fs. By using LMA fibers for spectral broadening, we further increased the pulse energy up to 20 nJ in the wavelength range of 1030-1215 nm [22]; such a powerful source enabled us to drive a video-rate laser scanning microscope to study human skin based on harmonic imaging [22].

Results

Conclusion