Method of assembling the optical module implementing Mach-Zehnder modulator

A process of assembling an optical module that includes an optical modulator, a beam combiner, and an output port, the optical modulator having a type of Mach-Zehnder modulator providing a first port that outputs a first beam and a second port that output a second beam, the first port being coupled with the output port through a first path that implements a first lens and a second lens thereon, the second port being coupled with the output port through a second path that implements a first lens and a second lens thereon, the beam combiner combining the first beam with the second beam and generating a combined beam to the output port, the first lenses on the first path and the second path being placed closer to the first port and the second port compared with the second lenses on the first path and the second path, respectively, the method comprising steps of:

• moving the first lenses on the first path and the second path closer to the first port and the second port by a preset distance from positions at which the first lenses on the first path and the second path convert the first beam and the second beam diffusively output from the first port and the second port into respective collimated beams;
• placing the second lenses at positions where the first beam and the second beam output from the first lenses couple with the output port with respective maximum coupling efficiencies;
• determining one of the second lenses that shows the maximum coupling efficiency greater than the maximum coupling efficiency shown by another of the second lenses;
• and
• equalizing the maximum coupling efficiencies by moving the one of the second lenses that shows the greater maximum coupling efficiency.