A method of reducing the optical path in spectral beam combining

Abstract

Listen

Translate article

We have demonstrated that the functions of focusing and collimating of the transformer lens in the traditional spectral beam combining systems can be achieved by two optical lenses. One lens focus all the beams from each emitter on the grating, which makes the beams superimposed in space; the other lens collimates the combining beam after the grating, to ensure a sufficient amount of feedback and make each emitter to be locked at different wavelengths. The first lens used for focusing doesn’t need to collimate the beams from each emitter, so the distance between the focusing lens and the front face of diode laser bar is no longer the focal length of transform lens and can be very short. So the optical path of the system is reduced by approximately half, which makes it convenient that spectral beam combining of multiple bars. A standard semiconductor laser array is employed in this experiment. Output power of 55.6 W and electro-optic conversion efficiency of 49.8% are achieved. The spectral line-width is 13 nm. M2 of 1.12×11.4 in horizontal and vertical directions are obtained. The beam quality of the output is close to that of a single emitter of the array in both directions.We have demonstrated that the functions of focusing and collimating of the transformer lens in the traditional spectral beam combining systems can be achieved by two optical lenses. One lens focus all the beams from each emitter on the grating, which makes the beams superimposed in space; the other lens collimates the combining beam after the grating, to ensure a sufficient amount of feedback and make each emitter to be locked at different wavelengths. The first lens used for focusing doesn’t need to collimate the beams from each emitter, so the distance between the focusing lens and the front face of diode laser bar is no longer the focal length of transform lens and can be very short. So the optical path of the system is reduced by approximately half, which makes it convenient that spectral beam combining of multiple bars. A standard semiconductor laser array is employed in this experiment. Output power of 55.6 W and electro-optic conversion efficiency of 49.8% are achieved. The spectral line-width is 1...