Pulse compression based on graded-index rods

We demonstrate a simple and robust platform for femtosecond pulse compression based on large-area graded-index (GRIN) rods. Despite highly-multimode propagation, pulses accumulate a spatially uniform nonlinear phase owing to the self-imaging property of GRIN media. In initial experiments, 420 fs and ∼100 nJ pulses are compressed to 60 fs duration with excellent beam quality and spatio-spectral homogeneity. Furthermore, simultaneous beam cleaning and pulse compression are possible with complex input beams. Similar compression performance is obtained with different input beam sizes and positions, which underlie the stability and ease of use of the GRIN rod compressor.