Abstract
        In this paper we present some investigations and analysis of various parameters that contribute for increasing the coupling 
efficiency of laser diode to single mode fiber coupling using ball lenses coupling scheme. Dual beams from Nd:YAG laser 
welding system have been used for the alignment and welding of the coupling components in a butterfly configuration. The 
process of attachment of fiber to laser diode and welding of various coupling components, such as lens holders, fiber ferrule 
and welding clips have been performed in what is so called active alignment process, where the system continues 
measuring the coupled power during the process of coupling and welding of coupling components in their holder to each 
other and to the main substrate. The experimentally measured coupling efficiency using double ball lenses coupling scheme 
was found to be around 75% with relaxed axial, lateral and angular misalignment tolerances. From theoretical calculations 
we found that by optimizing the separations between various components, coupling efficiency can reach 100% with relaxed 
misalignment tolerances. From the effect of lateral and angular offsets as well as the 1-dB misalignment tolerances 
calculations, the mode fields of laser diode and single mode fiber have been found to be effectively matched.
        Keywords
        Pigtailing- coupling efficiency – dual ball lenses - misalignment tolerances- laser welding.
        Citation
        MOHAMED FADHALI, SAKTIOTO, JASMAN ZAINAL, YUSOF MUNAJAT, JALIL ALI, ROSLY ABDUL RAHMAN, Coupling and attachment of single mode fiber into laser  diode transmitter, Optoelectronics and Advanced Materials - Rapid Communications, 2, 4, April 2008, pp.183-188 (2008).
        Submitted at: Feb. 8, 2008
 
        Accepted at: April 3, 2008