Department of Electrical and Electronics Engineering2024-11-0920040018-919710.1109/JQE.2004.8264382-s2.0-2442539210http://dx.doi.org/10.1109/JQE.2004.826438https://hdl.handle.net/20.500.14288/6443This paper provides a comprehensive description of the design of compact femtosecond solid-state lasers that are based on novel multipass cavity (MPC) configurations to extend the resonator length. of special importance are the q-preserving MPCs, which leave invariant the original spotsize distribution and Kerr lens mode-locking point of the short cavity. The general design guidelines of q-preserving MPCs are first reviewed and a novel configuration is proposed for the case where the MPC consists of notch mirrors. A class of non-q-preserving compact cavities is also analyzed and conditions needed to minimize the deviation from the q-preserving configuration are discussed. The design and performance of a q-preserving and a non-q-preserving mode-locked Ti: Al2 O3 laser are then described as examples. These compact oscillators measuring only 30 cm × 45 cm could produce pulses as short as 19 fs at a repetition rate of around 31 MHz. Up to ∼ 3.6 nJ of pulse energy could be obtained with only ∼ 1.5 W of pump power. Finally, two-mirror MPC geometries are examined to investigate the limits of compactness and energy scaling.Electrical engineeringJournal Articlehttps://www.scopus.com/inward/record.uri?eid=2-s2.0-2442539210&doi=10.1109%2fJQE.2004.826438&partnerID=40&md5=6cff4373e54d727daf818e05e27ab9a3Q212371