Optical module and method for manufacturing optical module

An optical module comprising:

• a first optical component and a second optical component including a multicore fiber (MCF);
• and
• a spatial joining part configured to optically couple the first optical component to the second optical component, wherein
• the first optical component includes a first uncoupled MCF and a first coupled MCF, the first uncoupled MCF having small optical coupling between cores, the first coupled MCF being located between the first uncoupled MCF and the spatial joining part, the first coupled MCF having a mode field diameter (MFD) larger than a MFD of the first uncoupled MCF,
• the second optical component includes a second uncoupled MCF and a second coupled MCF, the second uncoupled MCF having small optical coupling between cores, the second coupled MCF being located between the second uncoupled MCF and the spatial joining part, the second coupled MCF having an MFD larger than an MFD of the second uncoupled MCF,
• in the first coupled MCF and the second coupled MCF, crosstalk is periodically produced along length directions of the MCFs, and
• in the spatial joining part in which a large crosstalk is produced from the first coupled MCF, a total of a length of the first coupled MCF and a length of the second coupled MCF is length L in which the crosstalk is suppressed.