A beam parallelism testing method for multi-wavelength integrated collimating laser source

Abstract

The multi-wavelength integrated collimating laser source is the essential component of the receiving systems’ performance testing for various laser devices, by which the semiconductor laser chips with four typical peak wavelengths are bonded to the surface of the metal carrier. While because the structure of the four lasers are not of coaxial, thus their beam parallelism via the collimating optical system is a key index needed to be tested after the manufacturing process. A testing method based on the image acquisition and processing of the laser spots was proposed in this paper, which effectively solved the correction problem of the beam parallelism testing after the laser source was carried out. Firstly, the laser source and the collimator which internally installed a laser spot collector on its focus panel were aligned, and the laser spot from each semiconductor lasers was collected respectively; Secondly, the spot images were de-noised with the PDE (Partial Differential Equation) algorithm and each spot centroid was obtained sequentially. Finally the parallelism index of the multi-wavelength laser beams was gotten by the comparisons of the spot centroids. This method is of high testing accuracy and good versatility, and easy to operate, thus it has a wide application prospect.