25%Eu : KGd(WO4)2 laser crystal: spectroscopy and lasing on the 5D0→7F4 transition

25%Eu : KGd(WO4)2 crystal is grown by a modified Czochralski method and its spectral and lasing properties are studied. Generation of stimulated emission in this crystal on the 5D0→7F4 transition of the Eu3+ ion is obtained, as far as we know, for the first time. The laser operates at room temperature at a wavelength of ~703 nm under pumping into the 7F0→5D1 absorption band of the europium ion by the second harmonic of a Q-switched Nd : KGW laser (λpump= 533.6 nm). With a 9.4-mm-long active element, the output energy in the free-running regime reached 244 μJ, while the optical efficiency was 1.5%.