A 2 kw single-mode fiber laser with a 20-m long delivery fiber and high back reflection resistance has been demonstrated. An Yb-doped fiber with large core size and differential modal gain is used to realize high SRS suppression and single-mode operation simultaneously. The 20 m-long delivery fiber gives flexibility to the design of processing systems. An output power of 2 kW is achieved at a pump power of 2.86 kW. The slope efficiency is 70%. The power of the Stokes light is less than -50 dB below the laser power at the output power of 2 kW even with a 20-m delivery fiber. Nearly diffraction-limited beam quality is also confirmed (M2 = 1.2). An output power of 3 kW is believed to be achieved by increasing pumping power. The back reflection resistance properties of the fabricated singlemode fiber laser is evaluated numerically by the SRS gain calculated from measured laser output spectra and fiber characteristics. The acceptable power of the back reflection light into the fiber core is estimated to be 500 W which is high enough for processing of highly reflective materials. The output power fluctuation caused by SRS and back reflection in materials processing will be well suppressed. Our high power single-mode fiber lasers can provide high quality and stable processing of highly reflective materials.
We present an adaptive and robust pulse-operated high power fiber laser, which has an average output power of 30 W.
The fiber laser realizes flexible pulse duration without changing a repetition rate and an average power, which is
desirable for laser processing, by employing a Q-switched (Q-SW) Master Oscillator Power Amplifier(MOPA). For
instance, its pulse duration is controllable in the range of 50 ns to 100 ns at 50 kHz in repetition rate. In addition to the
flexible pulse duration, the fiber laser provides high powers, a peak power of 27 kW at 30 kHz in repetition rate and an
average power of 30 W at 50 kHz in repetition rate. Large mode area (LMA) fibers and end pumping structure in the
laser also contribute the above mentioned features, pulse adaptiveness and high output power. In terms of the
robustness of the laser, we employ newly-developed reflection-suppressing pump combiners, which protect pump laser
diodes (LDs) from amplified reflected signal light from objectives. All those features make the fiber laser a more
practical light source for laser processing.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.