Unitary mounting structure for semiconductor laser and optical fiber

Abstract

A mount arrangement of a semiconductor laser and an optical fiber as a unitary structure. A substrate has a submount disposed thereon mounting a semiconductor laser. The laser is fixed on the submount by a fusion-welding material. A fiber submount is disposed on the substrate in the vicinity of the semiconductor laser submount. An optical fiber is fixed to the fiber submount with its optical axis coaxial with the optical axis of the output light of the semiconductor laser. The fiber submount includes a material for fixing the optical fiber and has a melting point such that it will not affect the coaxial optical alignment of the semiconductor laser and the optical fiber and the fixing between the substrate, the laser submount and between the laser submount and semiconductor laser during fabrication. The thickness of the semiconductor laser submount and the fiber submount are selected in terms of the interrelation between the coefficients of linear thermal expansion of the materials forming them and the coefficient of linear thermal expansion of the optical fiber from the substrate, which are caused by temperature variations in a range including temperature variations during fabrication, are substantially equal to each other and displacement between the optical axes of the light output of the laser and optical fiber is avoided. The retention of the axes coaxial alignment minimizes reduction of the efficiency of the coupling of the optical fiber to the semiconductor laser.