An optical subassembly and an optical module are provided. The optical subassembly includes an optical transmitter, an optical receiver, an optical splitter, and an optical fiber stub. The optical transmitter is configured to transmit light from the optical transmitter to the optical fiber stub through the optical splitter. The optical splitter is configured to reflect light from the optical fiber stub to the optical receiver. An optical axis of the optical receiver and an optical axis of the optical fiber stub form an acute angle. An optical axis of the optical transmitter and the optical axis of the optical fiber stub also form an acute angle.