Patent ID: 8503492

Claim:
A mode-locked solid-state laser apparatus comprising: a resonator having an output mirror at one end of the resonator; a solid-state laser medium arranged in said resonator; and a saturable absorbing mirror; wherein said solid-state laser medium is arranged at a distance equal to or smaller than twice the Rayleigh range from said saturable absorbing mirror; said saturable absorbing mirror has a depth of absorbing modulation equal to or greater than 0.4%; said mode-locked solid-state laser apparatus is configured to impart a total intracavity dispersion D to light having a predetermined wavelength during a round trip of the light in said resonator, where the total intracavity dispersion D is smaller than zero and makes the light have such a pulse bandwidth that said saturable absorbing mirror can suppress operational modes other than operational modes generating soliton pulses repeated with a fundamental repetition period, and the absolute value |D| of the total intracavity dispersion D has a relationship expressed by an equation, τ P = 1.76 ⁢  D  ⁢ λ 0 ⁢ A eff , L 4 ⁢ π ⁢ ⁢ n 2 ⁢ l S ⁢ 1 E P , with a pulse width τ p and a central wavelength λ 0 of the light, a beam cross section A eff,L of the light in the solid-state laser medium, a nonlinear refractive index n 2 and a crystal length 1 s of the solid-state laser medium, pulse energy Ep in said resonator; and said output mirror is a negative-dispersion mirror which has a dielectric multilayer structure being formed on a substrate and comprising high-index layers having relatively high refractive indexes and low-index layers having relatively low refractive indexes which are alternately laminated, and the high-index layers and the low-index layers have optical thicknesses which randomly vary in a range of one-eighth to half of said predetermined wavelength, and the negative-dispersion mirror causes a mirror dispersion of −1000 fsec 2 to −600 fsec 2 in the light having said predetermined wavelength and realizes a reflectance of 97% to 99.5% at the predetermined length.