A coaxial transmitter optical subassembly (TOSA) including an optical fiber coupling receptacle coupled to a laser package may be used in an optical transceiver for transmitting an optical signal at a channel wavelength. The optical fiber coupling receptacle may include a housing having a first open end to receive a ferrule-terminated optical fiber. The receptacle may also include a fiber-coupling ferrule holding an optical fiber segment and secured within the housing to optically couple the optical fiber segment to a laser of the TOSA through a second open end of the housing opposite the first open end. The receptacle may further include a sleeve disposed on an interior surface of the housing to provide a cavity to secure the ferrule-terminated optical fiber and align the optical fiber to the optical fiber segment.