US Patent 7593443 Solid laser apparatus excited by a semiconductor laser

Single mode oscillation at a wavelength of about 1064.4 nm is enabled with no use of an etalon installed in an optical resonator by providing one of two ends of a Nd:YAG element, which acts as one end of the optical resonator, with an HR coating arranged for the wavelength of about 1064.4 nm and determining the thickness along the direction of transmission of light of the Nd:YAG element so that the peak of reflection appears at the wavelength of about 1064.4 nm but not at a wavelength of about 1062.8 nm.