The two pulse narrowing mechanisms are active gain modulation and saturable absorption.
Monolithic cavity devices with gain, gain modulation and saturable absorption functions integrated on a single semiconductor chip are easy-to-use.
The absorption may be clue to two photon absorption (TPA), excited state absorption (ESA), reverse saturable absorption (RSA), etc.
g], of the copolymer indicates that the operating nonlinear mechanism is reverse saturable absorption (RSA) (15).
We attribute the optical power limiting of the copolymer to reverse saturable absorption.