Research On Semiconductor Laser Beam Collimating

Laser diodes have been widely used in many fields such as military, industry and medicine use, however, a Laser Diode has large divergence angle, and the output beam must be collimated by optical systems in most practical work. Because of simple structure and easy fabricating, the cylindrical lenses have been used in many practical applications for beam collimating of LDs.A compound structure—Double Half-cylindrical Lens(DHCL) is proposed firstly by the author. On the basis of ray optics, the theoretical expressions of the collimated beam by a DHCL are derived, and the numerical results are also given. Both theoretical and numerical results indicate that a DHCL can be made from the high refractive index material, but a normal cylindrical lens can't, and the collimating performance of a DHCL is much better than that of a normal cylindrical lens, and the divergence angle of the collimated beam could be as small as 0.1 mrad.The non-spherical lens is another shaping system that is used to collimate the beam of LD, and the theoretic performance could be perfect. The mathematics description of the non-spherical lens is the most important problem for the beam shaping system design. A numerical simulating method and its precision analysis are given, and the results indicate that this method is simple, and can be used for the design of LD beam collimating system with non-spherical lens.