The K793DB2RN-4.000W is a 793nm 4W fiber-coupled laser diode — the only 793nm wavelength product in the ePhotonics catalog — delivering CW output at a center wavelength of 793nm (±3nm) through a 105µm core, 0.22 NA bare fiber. The 793nm wavelength is a critical pump absorption band for thulium (Tm³⁺)-doped fiber lasers, which emit in the 1900–2100nm mid-infrared range. The module’s feedback isolation band is specified exactly at 1900–2100nm, confirming its purpose-built design as a Tm-doped fiber laser pump source — protecting the diode from back-reflected Tm laser signal light at these wavelengths. A unique optical specification on this datasheet is the **spot ratio at 0.15/0.22 NA: 90% typical** — meaning 90% of the output power is contained within the 0.15 NA acceptance cone of the output fiber, even though the fiber’s full NA is 0.22. This is a beam quality metric that quantifies how efficiently the emitter’s fast-axis divergence is captured within a tighter NA budget, directly relevant when coupling into low-NA Tm fiber laser pump combiners that may accept only 0.15 NA. The spectral width of 3nm FWHM is also notably narrower than the 6nm typical on 808nm modules, reflecting the tighter emitter design at this wavelength. The fiber pigtail uses 0.9mm PVC tubing in a 1.5cm protective sleeve with a 245µm buffer diameter, bare (unterminated) fiber end, and 50mm minimum bending radius — the bare termination enabling direct fusion splicing into pump combiner components without a connector interface. Storage temperature extends down to −40°C (vs. −20°C on most other modules), and relative humidity tolerance reaches 85% (vs. 75%), reflecting a broader environmental specification for this optional-product format.