A transmitter optical sub-assembly includes a body and a receptacle assembled to a front side of the body, the receptacle including a nose body, a split sleeve enclosed by the nose body, a first body disposed behind the split sleeve, and a fiber stub either glued or shrink fit or pressed fit on to the first body, a rear end of the split sleeve being slip fitted on to the fiber stub; wherein the nose body is made from deep drawing or cold forging process and is attached on to a front surface of the body.