The K808DB2RN-4.000W is a compact fiber-coupled laser diode delivering 4W of Continuous Wave (CW) output power at a center wavelength of 808nm (±3nm). The defining electrical characteristic of this module is its exceptionally low maximum operating voltage of just 2V — the lowest operating voltage of any module in the entire 808nm lineup and among the lowest in the full catalog. This single-emitter architecture operates at a typical current of 4.5A (max 5.2A) against a 2V rail, making it uniquely compatible with low-voltage single-cell or dual-cell battery-backed power supply architectures in portable medical and handheld instrument designs. Despite its compact output power, the K808DB2RN-4.000W achieves 46% electrical-to-optical efficiency — the highest efficiency in the 808nm lineup — with a ±3nm wavelength tolerance and 6nm FWHM spectral width ensuring reliable overlap with Nd:YAG and Nd:YVO₄ absorption peaks for solid-state laser pumping. Output is delivered via SMA905 termination through a 105μm core, 0.22 NA fiber in 0.9mm loose tubing with a compact 1.5-meter pigtail and 50mm minimum bending radius — the same high-brightness fiber geometry as the 60W and 70W modules, but in a low-power entry-level package. The 30dB feedback isolation (1020–1200nm) protects the diode from back-reflected Nd or Yb laser signal light in pumping configurations, and the simple 2-pin package with no optional monitoring pins keeps integration minimal. With a standard 15–35°C operating temperature range and SMA905 connectivity, this module serves as the low-power anchor of the 808nm SMA905 pump lineup.