Mapping of Temporal Coherence Function for Ultrafast Lasers via Statistical Fringe Analysis of Reconstructed Phase Maps

The group developed a method to generate two-dimensional temporal coherence maps for ultrafast lasers using statistical fringe analysis of reconstructed phase maps.

Abstract:

A technique for generating two-dimensional temporal coherence maps for ultrafast lasers using statistical fringe analysis of reconstructed phase maps is proposed and demonstrated experimentally. A tilted mirror in a Michelson-type digital holographic setup was used as the test object with varying depth, thus introducing a varying optical path difference between the two beams. Due to the short coherence of the ultrafast laser used, the recorded hologram and, subsequently, the reconstructed phase map appeared only within a local area in the transverse plane. Noise-robust and precise determination of the phase map area was facilitated using a statistical algorithm yielding the two-dimensional temporal coherence map, which eliminates the common problems of the conventional techniques. The proposed technique offers fast and direct calculation of temporal coherence length of ultrafast lasers.

Experimental holograms and the coherence functions obtained using the phase-based coherence measurement technique. (a)-(c) are the recorded holograms, (d)-(f) are the intensity line scans, and (g)-(i) are the two-dimensional temporal coherence maps. Left, middle and right columns correspond to laser bandwidth settings A, B, and C, respectively. Video file (989 kB). Image courtesy: E. Escoto, et al, Optics Communications 329, 190-195 (2014)

Bibliographic entry:

E. Escoto, J. Muldera, L. Dasallas, E. Estacio, and P.F. Almoro, “Mapping of Temporal Coherence Function for Ultrafast Lasers via Statistical Fringe Analysis of Reconstructed Phase Maps,” Optics Communications 329, 190-195 (2014). doi:10.1016/j.optcom.2014.04.072.