Proceedings Article | 6 June 1995
KEYWORDS: Diodes, Semiconductor lasers, Neodymium lasers, Nd:YAG lasers, Mirrors, Polarization, Output couplers, Absorption, Oscillators, Pulsed laser operation
A new technique for combining two diode laser beams to a laser rod is demonstrated. By taking advantage of the two absorption peaks of Nd:YAG around 795 and 809 nm, and of Nd:YLF around 794 and 807 nm, a dichroic mirror was used as the combining element of two diode lasers lasing at different wavelength at room temperature. Using an end-pumped geometry, an oscillator pumped by two 2 W diode lasers (SDL - 2372-P1) was built. In the free-running mode of operation, total light to light conversion efficiencies of 26%, 29%, and 31.5% with 0.31, 0.32, and 0.35 slope efficiencies were achieved for Nd:YAG pumping with the 795 nm, 809 nm and the two diodes together (with a total of 4 W), respectively. In the case of the free-running Nd:YLF the total light to light conversion efficiencies were 33%, 26%, and 31% with 0.41, 0.33, and 0.36 slope efficiencies, for the same pumping situations. For q-switched operation and pump pulse width duration of approximately 1 fluorescence lifetime the Nd:YAG efficiencies were 10%, 11%, and 13%, and for Nd:YLF 11.5%, 10%, and 10.5%, for the same pumping cases. Using this coupling scheme the output of the laser was effectively doubled. The beam quality was approximately 1.1 diffraction limited in all cases. This technique is suitable for pumping other lasing materials such as Nd:YVO4 and Nd:BEL around 800 nm, and Cr:LiSrAlF6 around 680 nm.
