Cutting-edge and Future Saturable Absorbers

By James Van Howe

From CTuII2

This post originally appeared on Jim’s Cleo Blog and is reproduced with permission from its author.

Khanh Kieu, from University of Arizona, began his talk, CTuII2,”Generation of sub-20fs pulses from an all-fiber carbon nanotube mode-locked laser system” emphasizing the importance of saturable absorbers (SA) in mode-locked lasers. The SA is the device that is responsible for locking the modes in a laser cavity, thereby allowing the creation of pulses. Without one, you’d just have a continuous wave laser. In general, a saturable absorber is any device that transmits higher intensities of light at expense of lower intensities. They can be active, passive, real, or artificial. In ultrafast fiber-lasers, the typical SA of choice is a semiconductor saturable absorber mirror, SESAM,  (a real SA relying on material response) or nonlinear polarization evolution, NPE, (an artificial one making use of polarization tricks). Kieu’s point is that it makes sense to spend time developing the component of the mode-locked laser that is responsible for mode-locking.

Kieu and his collaborators at Arizona have been doing just that by developing SAs using carbon nanotubes. Though not the primary motivation, Amer Nevet, from Technion in Haifa, and his collaborators have also been developing effective SAs  by showing the first example of two-photon gain in semiconductors, CKK1, “Direct Observation of Two-Photon Gain in Semiconductors.” ...Read the full post by clicking here.

Posted: 20 May 2010 by James Van Howe | with 0 comments

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