Laser amplifier

A solid-state laser comprising:

• two mirrors defining a resonator,
• at least two laser-active media disposed in the resonator in a common laser radiation field, wherein the laser-active media do not form a hard aperture for the laser radiation field and the laser-active media each define a plane that is penetrated by the laser radiation field,
• at least one focusing optical element disposed in the laser radiation field between two adjacent ones of the at least two laser-active media,
• wherein a focal length and a distance of the focusing optical element from the planes of the two adjacent laser-active media are each selected such that the planes of the laser-active media are approximately mapped onto each other by a near-field far-field transformation.

A method of forming a laser amplifier, the method comprising:

• focusing pump radiation onto a first plane defined by a first laser-active medium;
• focusing pump radiation onto a second plane defined by a second laser-active media;
• focusing laser radiation between the first and second planes with an optical element in a laser radiation field extending between the first and second laser-active media;
• selecting a focal length of the optical element and separating the optical element from the first and second planes such that the first and second planes of the laser-active media are approximately mapped onto each other through a near-field far-field transformation.