OPTICAL MODULE

PURPOSE:To increase the coupling efficiency by fitting a ferrule in a cylinder body while setting the direction of the optical axis of a held optical fiber to the direction wherein projection light is made incident and refracted according to the Snell's law. CONSTITUTION:The ferrule 5 before being incorporated in the cylindrical case 7 holds the optical fiber F previously and has its end surface polished slantingly. Then the laser light projected from a semiconductor laser 1 after being converted by a coupling lens 2 is made incident on the optical fiber F. At this time, the light from an air layer is made incident on the optical fiber F, i.e., a medium which is different in refractive index, so the laser light is refracted at an angle theta deg. according to the Snell's law, so the optical axis direction of the optical fiber F which is held by the ferrule 5 by fitting the ferrule 5 to the cylindrical case 7 slantingly at the angle theta to the optical axis X-X' is matched to the refraction direction of the laser light. Therefore, the laser light is refracted and incident in the direction of the optical axis of the optical fiber F, so the coupling efficiency is easily improved.