inserted into the attachment part 23 and can be fixed thereto by an attachment screw part detailed structural explanation are omitted here the optical fiber is capable of being attached to or removed from the receptacle the relative positions of the dummy fiber 17 the ferrule 18 the holder 19 and the housing 20 are settled beforehand both the dummy fiber 17 and the ferrule 18 have end surfaces slantingly polished the direction of the lowest point 32 is denoted by a certain mark 31 on the outside wall of the housing 20 this mark 31 should coincide with the deviation direction x direction of the laser chip and the holder 19 and the housing 20 are in contact with the sleeve 14 hence the lowest point 32 of the ferrule slanting end surface coincides with the deviation direction x direction of the laser on the pole 6 under these coincident conditions the housing 20 is moved on the sleeve 14 parallel in xy plane for seeking a point at which the power attains the maximum by measuring the power of light propagating at the end of the optical fiber and is fixed to the sleeve 14 at a position where the maximum power of light is able to be obtained a position deviating in x direction.