40 W All-Fiber Er/Yb MOPA System Using Self-Fabricated High-Power Passive Fiber Components

Pawel Kaczmarek,Dorota Stachowiak,Krzysztof Abramski

doi:10.3390/app8060869

Abstract

In this work, we demonstrate a three-stage all-fiber master oscillator power amplifier (MOPA) system emitting over 40 W of continuous-wave (CW) output power at ~1.5 µm. The setup utilizes three self-fabricated high-power passive fiber components: a mode-field adaptor (MFA) and two types of pump and signal power combiners. Their development allowed us to become independent from commercially available components, which are often incompatible with fibers used in the experimental setups, resulting in additional losses. A power combiner with single-mode (SM) signal fibers in a configuration (5 + 1) × 1 was used in the second stage of the MOPA system, which was based on an SM Er–Yb co-doped double-clad (DC) fiber. The fabricated MFA was used to connect the second amplifier stage based on SM fibers with the third amplifier stage based on large-mode-area (LMA) fibers. In the third stage of MOPA system, based on Er–Yb LMA DC fibers, we used the fabricated power combiner based on LMA-type signal fibers in a configuration (6 + 1) × 1. The presented three-stage MOPA system, utilizing self-fabricated high-power passive fiber components, enables amplification of an input signal of 10 mW up to 44 W of the CW power at the wavelengths of 1555 nm and 1563 nm, corresponding to a gain level of approximately 36.4 dB.

Highlights

High-power fiber sources, operating in a 1.55 μm spectral range in a master oscillator power amplifier (MOPA) configuration, are very attractive alternatives to solid-state lasers in many applications
Almost all parameters of MOPA systems are determined by seed laser, while output power or pulse energy depends on amplification stages
We demonstrated a three-stage MOPA system performed in the all-fiber construction, providing more than 40 W of CW output power at the wavelengths of 1555 nm and 1563 nm

Summary

Introduction

High-power fiber sources, operating in a 1.55 μm spectral range in a master oscillator power amplifier (MOPA) configuration, are very attractive alternatives to solid-state lasers in many applications. In a three-stage MOPA system, the first stage for low-power amplification (output power below 1 W) is utilizing active single-mode single-clad (SM-SC) fibers In this case, an input seed signal and pump power are coupled into the core of the active fiber. This allows using higher levels of pump power with simultaneously lower optical power density per unit area than that in the case of the active SM-SC fiber This is why in the third amplifier stage for high-power amplification (output power of dozens or more watts), a large-mode-area double-clad (LMA-DC) fiber with a larger inner cladding should be used. Such a fiber is capable to handle both: high-power pump and signal transmission. All the components were fabricated using Large Diameter Splicing System (LDS): three-electrode advanced fiber splicer which enabled tapering of single fibers or fiber bundles, splicing and cleaving fibers with diameters from 80 μm up to 2 mm [34]

First and Second MOPA Stage

Experimental

SetupAofsetup

Alterative

Experimental Results

Conclusions