High power fiber amplifier with adjustable repetition rate for use in all-fiber supercontinuum light sources

摘要

In recent years the use of supercontinuum light sources has encouraged the development of various optical measurement techniques, like microscopy and optical coherence-tomography. Some disadvantages of common supercontinuum solutions, in particular the rather poor stability and the absence of modulation abilities limit the application potential of this technique. We present a directly controllable all-fiber laser source with appropriate parameters in order to generate a broad supercontinuum spectrum with the aid of microstructured fibers. Through the application of a laser seed-diode, which is driven by a custom built controller to generate nanosecond pulses with repetition rates in the MHz range in a reproducible manner, a direct control of the laser system is enabled. The seed-signal is amplified to the appropriate power level in a 2-step amplification stage. Wide supercontinuum is finally generated by launching the amplified laser pulses into different microstructured fibers. The system has been optimized in terms of stability, power-output, spectral width and beam-quality by employing different laser pulse parameters and several different microstructured fibers. Finally, the system as a whole has been characterized in reference to common solid state-laser-based supercontinuum light sources