Research On Coupling Models And Rules For Coaxial Laser Diode Packaging

ABSTRACT:The optical coupling technique for coaxial laser diode packaging in the optical fiber communication was studied, the models and rules of the optical coupling between laser diode and single mode fiber was researched theoretically and experimentally. In various methods of coupling, the ball lens, the spherical lensed fiber and the cylindrical lensed fiber were selected to establish models and analyze coupling characteristics in detail. Then, the special optical properties of graded index fiber were studied, the coupling system with graded index fiber was researched and designed. This paper provides a theoretical and technical guidance for the efficient coupling of coaxial laser diode packaging, the main contents are as follow:(1) The properties of laser diode beam were analyzed, the propagation theory about the Gaussian beam was introduced. The ball lens coupling model was established and the coupling characteristics such as the effects of beam properties, parameters of the ball lens, offset of spatial location was studied afterwards. At last, the coaxial optoelectronic devices were designed, the coupling efficiency is about20%. The actual characteristics were obtained by experimental study and comparative investigation of the theoretical model and experimental results was completed.(2) The technique of the spherical lensed fiber and the cylindrical lensed fiber for coupling to a laser diode was analyzed, the coupling models were established and the coupling characteristics were studied. Then the fabrication precision of micro-lens and the alignment error tolerance were studied. Based on the results, the spherical lensed fiber was designed, in the experimental study, the coupling efficiency was upper to47%.(3) In order to improve the short working distance of ordinary lensed fiber, the graded index fiber was introduced. The performance of the graded index fiber in the optical coupling system was studied, the special spherical lensed fiber model with the application of graded index fiber was established and the coupling characteristics were studied. The high coupling efficiency, long working distance coupling system was designed, in the experimental study, the working distance increased by150%compared to the ordinary lens fiber.