Efficient self-frequency doubling of Nd:GdCOB crystal by type-I phase matching out of its principal planes

Abstract We report on the efficient self-frequency doubling of Nd:GdCOB crystal by type-I phase-matching at θ =66.3° and ϕ =134.4°, which is out of its principal planes. A CW output power of 225 mW at 530.5 nm is obtained at an absorbed pump power of 1.56 W with an optical conversion efficiency of 14.4% and an absorbed threshold pump power of 1.8 mW. To our knowledge, this is the highest output power, the highest efficiency and the lowest threshold obtained from a self-frequency-doubled Nd:GdCOB laser to date.