Ultra low-noise coherent supercontinuum amplification and compression below 100 fs in an all-fiber polarization-maintaining thulium fiber amplifier.

Anupamaa Rampur,Tomasz Kardaś,Mariusz Klimczak,Yuriy Stepanenko,Grzegorz Stępniewski,Dirk-Mathys Spangenberg,Dominik Dobrakowski,Thomas Feurer,Alexander Heidt

doi:10.1364/oe.27.035041

Abstract

We report an ultra-low noise, polarization-maintaining, ultrafast Thulium-doped all-fiber chirped pulse amplifier, seeded by a polarized all-normal dispersion (ANDi) supercontinuum (SC) driven by an ultrafast Erbium-fiber laser. The system comprises only polarization-maintaining fibers and delivers 96 fs pulses with 350 mW output power at 100 MHz, centered at 1900 nm. The integrated relative intensity noise (RIN) in the range of 10 Hz - 10 MHz is only 0.047% at the amplifier output, which is virtually identical to the RIN of the Erbium-fiber laser driving the SC. Therefore, neither the SC generation nor the amplification process introduce significant excess noise. The RIN of our system is an order of magnitude lower than similar systems previously seeded with Raman solitons. This highlights the superior noise properties of ANDi SC and their potential as ultra-low noise seed sources for broadband, high power ultrafast fiber amplifiers and frequency combs.

Highlights

Broadband coherent seeding of ultrafast rare-earth doped optical amplifiers enables the realization of high peak power, ultrashort pulse light sources using optical fibers
The successful amplification and recompression of all-normal dispersion supercontinuum pulses provide experimental evidence for the feasibility of ultra-low noise, coherent seeding of ultrafast fiber amplifiers operating at pulse duration below 100 fs in the 2 μm wavelength window
Compared to earlier realizations of ultrafast seeding of fiber amplifiers using anomalous dispersion nonlinear dynamics, the major advance of our system is the elimination of noise amplifying nonlinear effects from the spectral broadening and amplification stages

Summary

Introduction

Broadband coherent seeding of ultrafast rare-earth doped optical amplifiers enables the realization of high peak power, ultrashort pulse light sources using optical fibers. Many reported ultrafast fiber amplifier systems operating in the 2 μm spectral range are coherently seeded by modelocked Erbium (Er)-fiber systems, which are spectrally broadened to around 2 μm wavelengths through the generation of Raman-shifted solitons, four-wave mixing, or supercontinuum (SC) generation in spectral range, where a highly nonlinear fibers has anomalous dispersion [2,3,4,5,8,9,10,13] This allows the straightforward extension of the maturity and excellent performance parameters of Er:fiber technology to longer wavelengths and easy power scaling. Amplification of white noise during the nonlinear broadening of the Er-fiber seed system in the anomalous dispersion region of a highly nonlinear fiber has been identified as one of the major performance limitations for the further evolution of high power frequency combs at 2 μm, leading to 0.5% of integrated RIN (10 Hz – 30 MHz) at the amplifier output. [8] Direct amplification schemes of Tm-doped mode-locked fiber lasers using anomalous dispersion nonlinear dynamics for pulse shortening, such as nonlinear self-compression, face similar noise challenges (e.g. 0.34% RIN in a frequency range from 10 Hz to 11 MHz in a recently reported 50 fs system) [15]

Methods

Results

Conclusion