Single crystal fiber (SCF) is a hybrid laser architecture between conventional bulk laser crystals and active optical fibers
allowing higher average powers than with conventional crystals and higher energy than with fibers in pulsed regime. The
pump beam delivered by a fiber-coupled laser diode is confined by the guiding capacity of the SCF whereas the signal
beam is in free propagation. In this paper, we study the pump guiding in the SCF and give an overview of the results
obtained using SCF gain modules in laser oscillators and amplifiers. We report about up to 500 μJ nanosecond pulses at
the output of a passively Q-switched Er:YAG SCF oscillator at 1617 nm. High power experiments with Yb:YAG
allowed to demonstrate up to 250 W out of a multimode oscillator. High power 946 nm Nd:YAG SCF Q-switched
oscillators followed by second and fourth harmonic generation in the blue and the UV is also presented with an average
power up to 3.4 W at 473 nm and 600 mW at 236.5 nm. At 1064 nm, we obtain up to 3 mJ with a nearly fundamental
mode beam in sub-nanosecond regime with a micro-chip laser amplified in a Nd:YAG SCF. Yb:YAG SCF amplifiers are
used to amplify fiber based sources limited by non-linearities such as Stimulated Brillouin Scattering with a narrow
linewidth laser and Self Phase Modulation with a femtosecond source. Using chirped pulse amplification, 380 fs pulses
are obtained with an energy of 1 mJ and an excellent beam quality (M2<1.1).
We describe a multi-stages single crystal fiber (SCF) amplifier for the amplification of femtosecond pulses with radial or azimuthal polarization in view of high speed material processing (surface structuring, drilling). We demonstrate a three stages diode-pumped Yb:YAG single crystal fiber amplifier to achieve femtosecond pulses at an average power of 85W at 20 MHz in radial and azimuthal polarization.