Avoidance of mode instability in an optical amplifier fiber

摘要

The invention relates to a method for stable transmission of laser radiation through an optical waveguide (3), wherein two or more modes of the laser radiation propagating in the optical waveguide (3) interfere and form a mode interference pattern in the optical waveguide, whereby a thermally induced refractive index grating in the optical waveguide (3 ) is produced. It is an object of the invention to provide an effective approach to stabilize the output signal of the optical waveguide (3) in a fiber-based laser / amplifier combination at high output powers, i. To avoid mode instability. This object is achieved by the invention in that a relative spatial phase shift between the mode interference pattern and the thermally induced diffraction grating is set in the propagation direction of the laser radiation. Moreover, the invention relates to a laser / amplifier combination with a laser (1) and an optical waveguide (3) in the form of an amplifier fiber, wherein the optical waveguide (3) amplifies the propagating therein radiation of the laser (1). The invention proposes an actuating element (7) which generates a predeterminable relative spatial phase shift of the mode interference pattern and of the thermally induced refractive index grating in the propagation direction of the laser radiation.