1. Field of the Invention
The present invention relates to light-emitting modules for light communication, and in particular to a light-emitting module which is preferably used as a pig tail type in which an optical fiber is fixed.
2. Description of the Related Art
In a pig tail type of light-emitting module in which a laser diode, a lens and an optical fiber are incorporated, a laser beam emitted from the laser diode is converged by the lens and the laser beam converged by the lens and then optically coupled with the optical fiber. Such optical coupling requires not only essential accurate alignment in directions (X- and Y-directions) perpendicular to the optical direction of the laser beam in the optical fiber, but also accurate alignment in the direction (Z-direction) of the optical axis due to variations in the position of the laser diode chip when the chip is manufactured. Therefore, conventionally, the laser diode and the lens are aligned at first so as to be incorporated, and subsequently, the three components being the laser diode, the lens and the optical fiber are incorporated by adjusting the optical fiber in the X-, Y- and Z-directions.
However, according to the above conventional light-emitting module, the optical fiber must be tri-axially adjusted in the X-, Y- and Z-directions, which requires not only a complicated adjusting mechanism but also considerable time for adjustment. This greatly increases manufacturing cost. In general, a laser diode with a cap has various chip position shifts of approximately .+-.60 .mu.m in the X-, Y- and Z-directions, thus, if adjustment in the Z-direction is omitted, coupling efficiency greatly deteriorates, which disadvantageously causes deterioration in performance of the light-emitting module.