We present a detailed design of a simple, stable, and compact tapered amplifier (TA) diode system. Heat conductivity, strain release, and system alignment are taken into consideration for this design. Convenient access to the three-dimensional adjustments for collimation makes the system easy to align. The optical amplification is discussed as a function of injection of current and operating temperature for both a continuous-wave external cavity diode laser (CW-ECDL) and a mode-locked external cavity diode laser (ML-ECDL). With 5-mW CW-ECDL seeding power, 240 mW is achieved after the TA, 115 mW (48%) of which can be coupled into a single-mode fiber. With 0.75-mW average ML-ECDL seeding power, 80-mW average power, or about 11-W peak power (843-MHz repetition rate and 8-ps pulse width), is achieved after the TA, 39 mW (49%) of which can be coupled into a single-mode fiber. In both cases, the amplified light maintains the optical properties of the seeding light, showing the same mode suppression. The output power spatial mode quality is characterized with a camera and BeamView software. Output power stability is also discussed.