Systems, methods, and apparatus for an optical sub-assembly (OSA) are disclosed. In one or more embodiments, the disclosed apparatus involves a package body, and a lock nut, where a first end of the lock nut inserted into a first cavity of the package body. The apparatus further involves a transistor outline (TO) can, where a first end of the TO can is inserted into a second cavity of the package body. Also, the apparatus involves an optical fiber, where a portion of the jacket from an end of the optical fiber is stripped off, thereby exposing bare optical fiber at the end of the optical fiber. The end of the optical fiber is inserted into a second end of the lock nut such that the bare optical fiber passes into the package body and at least a portion of the bare optical fiber is inserted into the TO can cavity.