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 CW-ECDL seeding power, is achieved after the TA, (48%) of which can be coupled into a single-mode fiber. With average ML-ECDL seeding power, average power, or about peak power ( repetition rate and pulse width), is achieved after the TA, (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.