We report on the development of diode-pumped high power continuous-wave (CW) and ultrashort pulse Yb:KGW lasers for applications in nonlinear multimodal microscopy. In the CW regime we generated 5W of average output power from a simple three-mirror cavity, with 22% of optical-to-optical conversion efficiency. The CW laser was used as a platform for development of a high power mode-locked oscillator. We achieved 2.3W of average output power in the mode-locked regime with ~210 fs duration pulses centered around 1047 nm at a repetition rate of 97 MHz. This corresponds to 24 nJ of energy per pulse and 114 kW of peak power. The demonstrated laser will be used in second- and third-harmonic generation microscopy of biological samples.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.