a solid state laser excited by a semiconductor laser can generate a stable and highly efficient high power laser beam . the laser apparatus includes a solid state laser element containing an active medium , a semiconductor laser for optically exciting the solid state laser element , a power supply for supplying pulses of current having magnitudes that change with time during each pulse to the semiconductor laser , and an optical resonator for emission of a laser beam from the solid state laser element . when the semiconductor laser is driven with the pulses that change in magnitude during each pulse , it produces pulsed excitation light that excites the solid state laser element . a stable laser beam is produced because changes in thermally sensitive light - generating parameters of the semiconductor laser are compensated .