Optical module

An optical module comprising:

• a polarization controller that includes
• a main body including a polarization multiplexer and demultiplexer portion that, upon input of two kinds of light that are in perpendicularly-polarized states, performs polarization multiplexing on the two kinds of light and output polarization-multiplexed light, and upon input of light, performs polarization demultiplexing on the light and outputs two kinds of light that are in perpendicularly-polarized states,
• a first polarizer,
• a first input portion,
• a second input portion,
• a third input portion,
• a first output portion, and
• a second output portion;
• an optical device configured to receive input of light via the polarization controller and output light via the polarization controller;
• and
• a first optical fiber, wherein
• the optical device is configured to output first light and second light to the polarization controller,
• the polarization controller is configured to perform, by the polarization multiplexer and demultiplexer portion, polarization multiplexing on the first light that is input from the first input portion and the second light that is input from the second input portion, and output polarization-multiplexed light as third light from the first output portion, and
• the polarization controller is configured to allow fourth light that is output from the first optical fiber and input from the third input portion to pass through the first polarizer and output the fourth light from the second output portion to the optical device,
• the polarization controller includes a half wave plate configured to rotate a polarization direction of the second light, and
• the half wave plate is located on an opposite side of the first polarizer with respect to the main body such that no physical interference occurs between the half wave plate and the first polarizer.