Bidirectional optical module and optical time domain reflectometer

An optical time domain reflectometer that tests loss characteristics of an optical fiber, comprising:

• a bidirectional optical module that emits light toward the optical fiber and receives light returning from the optical fiber;
• a bidirectional optical module drive unit that drives the bidirectional optical module so as to emit light with predetermined timing;
• an electrical signal conversion unit that converts light having entered the bidirectional optical module to an electrical signal;
• and
• a signal processing unit that determines through calculation the loss characteristics of the optical fiber based on the electrical signal resulting from the conversion executed by the electrical signal conversion unit, wherein
• the bidirectional optical module includes:
• a plurality of light emitting elements that emit light to enter the optical fiber;
• a light receiving element that receives light having exited the optical fiber;
• and
• a non-reciprocal unit for making an optical path in a forward direction from the light emitting element to the optical fiber and an optical path in a backward direction from the optical fiber to the light emitting element different,
• wherein polarization planes of light incident on the optical fiber after being emitted from the plurality of light emitting elements are mutually orthogonal, and the non-reciprocal unit emits returning light of the light emitted from the plurality of light emitting elements from the optical fiber toward the light receiving element to one light receiving element,
• wherein the light emitted from the plurality of light emitting elements is emitted from a first port or a second port,
• wherein the light emitted from the first port is incident on the non-reciprocal unit with an inclination at an angle in a positive direction greater than zero with respect to an optical axis of the non-reciprocal unit, and
• wherein the light emitted from the second port is incident on the non-reciprocal unit with an inclination at an angle in a negative direction greater than zero with respect to the optical axis of the non-reciprocal unit.