Abstract

The anti-resonant ring (ARR), first introduced by Siegman,¹ has found many applications, most recently in colliding-pulse mode-locked lasers.² Here, we introduce the use of the ARR as a detection arrangement for performing ultrafast excite-probe experiments, where it offers many advantages over current techniques. Specifically, it allows the removal of dc or slow effects from the measured ultrafast transient by optically subtracting off the dc or slow component automatically (and more accurately than by electronic subtraction). Also, by deliberately allowing some leakage from the ring, optical homodyne detection (OHD) is possible, yielding both the absorption and refractive-index transients. By choosing the best leakage value in this mode, maximal signal-to-noise ratios can be achieved for a given amount of laser shot-to-shot jitter. Further, a continuum probe may be used because there is no phase-matching requirement. Finally, it appears that undesired effects that are often problems in excite-probe experiments, such as thermal beam deflection and coherence spikes, may be cancelled in an ARR.

© 1990 Optical Society of America