Saarinen, Esa J.Lyytikainen, JariRanta, SannaRantamaki, AnttiSaarela, AnttiSirbu, AlexeiIakovlev, VladimirKapon, EliOkhotnikov, Oleg G.2016-10-182016-10-182016-10-18201610.1117/12.2209384https://infoscience.epfl.ch/handle/20.500.14299/130085WOS:000381884900016We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the >40 nm tuning range make the laser a promising tool for medical treatments that rely on photosensitizing agents and biomarkers in the transmission window of tissue between 700 and 800 nm. The InP-based gain structure of the laser was wafer-fused with a GaAs-based bottom mirror and thermally managed with an intracavity diamond heat spreader. The structure was pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.Semiconductor disk laserVertical External Cavity Surface Emitting Laser (VECSEL)wafer fusionfrequency doublingsecond harmonic generationbismuth borate crystaltunable lasertext::conference output::conference proceedings::conference paper