Connector

A connector, comprising:

• a housing;
• a ferrule assembly disposed at least partially inside the housing, wherein the ferrule assembly comprises:
• a first outer wall;
• a ferrule comprising a first end;
• a flange coupled to the first end and comprising a second outer wall, wherein the second outer wall comprises a mounting hole;
• and
• a first channel disposed inside the ferrule and the flange, wherein a guide structure is assembled at the mounting hole, and wherein the guide structure comprises:
• a guide channel coupled to the first channel;
• and
• a first light transmission hole coupled to the guide channel;
• an optical fiber disposed at least partially inside the ferrule assembly, wherein the optical fiber comprises a main optical fiber and a branch optical fiber extending diagonally from the main optical fiber;
• a first light transmission part disposed on the first outer wall;
• and
• a second light transmission part disposed on the housing,
• wherein a second light-transmitting hole in the second light transmission part and the first light-transmitting hole in the first light transmission part at least partially overlap to define a visible window configured for observation of light carried on the optical fiber via at least one of the main optical fiber or the branch optical fiber.