Abstract

It has recently become possible to generate ultra-broadband continuum from 400 to 1600 nm with a TEM₀₀ spatial mode.¹ This involves simply allowing sub-nanojoule 800-nm pulses to propagate through a short length of newly developed microstructure optical fiber, which can be nearly dispersion-free in the visible. We have made cross-correlation-FROG (XFROG) measurements of the continuum." These measurements nicely reveal the parabolic group delay of the pulse. However, the retrieved spectrum from our XFROG measurements has much more structure than the directly measured spectrum. Also, we observe fine-scale structure in the retrieved trace that is not seen in the measured trace, a clear indication that something is amiss. Usually, such poor agreement indicates that the more difficult measurement—the XFROG measurement—is contaminated with systematic error.

© 2002 Optical Society of America