High speed industrial laser transfer printing requires high power lasers that can deliver pulses on demand and having arbitrary pulse duration in range of few nanoseconds to milliseconds or more. A special kind of MOPA fiber laser is presented using wavelength multiplexing to achieve pulses on demand with minimal transients. The system is further tested in printing application.
A gain switched pulsed laser based on ytterbium doped rod PCF type fiber is presented. The high performance pump
system was based on 976 nm laser diodes incorporating high speed and high current laser diode drivers with active
feedback loop based control that enable high pulse to pulse stability. Furthermore the temperature control ensure the
adequate output spectrum of the pump laser diodes in order to match maximum of the absorption peak of Yb doped
active medium. The pulses duration in range between 48 ns to 75 ns were achieved with peak powers up to 3.6 kW.
Further, the change of the laser output spectrum in regard to the pump pulse power is observed.
First pulse of relaxation oscillations that appear after the start of the pumping can be used to realize an efficient pulsed laser based on gain switching. Because there is no need for any additional active optical element this can be very simple and robust technique to produce nanosecond pulses. Together with fiber technology it can produce compact and reliable lasers appropriate for industrial applications such as micro-processing. However, to produce pulses with appropriate peak power and duration, one must carefully design such systems. We report on a numerical model that describes time and spatial dependencies of photon and ion populations which was developed to enable design and optimization of a gainswitched fiber laser. The peak pump power influence on basic output laser pulse parameters is presented in this paper. To confirm theoretical result an experimental setup was built around double clad ytterbium doped fiber laser.
We present a study of a gain-switched end-pumped Yb-doped-fiber laser. The test laser that was mainly used in order to
verify the theoretical model consist of an 8.7 m long double clad active fiber with core and inner cladding diameter of
8 μm and 130 μm respectively, and absorption of 1.5 dB/m. An important part of the system is a control unit that
switches on the pumping diodes at a desired repetition rate and switches off at the moment when the first spike of the
transitional effect appears in order to suppress additional oscillations.
A simple rate equation model accurately predicts the main pulse parameters. It describes the population dynamics of the
photons and the laser levels, including the occupation by thermal effects. Further numerical simulations show that with
adequate active fiber geometry, active ion doping and sufficient pumping power, much shorter pulses in range of 50 ns
and peak power of several 100W can be achieved. Such a simple system with the potential addition of a one stage active
fiber amplifier can be interesting for some applications in micro-processing like scribing of solar cells, micro processing,
and thin film removal.