Abstract
We propose a new modulation technique for phase-sensitive detection to extract a cross-term signal appearing in multi-pulse experiments and demonstrate the selective detection of cross-term signal on two-pulse correlation measurements. This modulation technique can be widely applied to the selective detection in multi-beam laser experiments such as two-pulse correlation, auto-correlation, and double-resonance experiments, because the selectivity can be realized by using a conventional single-frequency mechanical chopper and 2<i>f</i> phase-sensitive detection. The effectiveness of the proposed technique was confirmed by two-pulse correlation measurements of two-photon-excited fluorescence from rhodamine 6G. In addition to the selective observation of a correlation peak, the technique succeeded in observing a weak correlation background. By combining asymmetric, two-pulse correlation measurements with the proposed technique, it was clarified that the background was produced by a three-photon process and assigned to fluorescence depletion caused by an up-conversion process. The results indicate that the cross-term selective, two-pulse correlation method that is based on the phase-shifted parallel modulation technique is powerful tool to find and analyze a high-order optical event buried in a low-order optical event.
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription