The K878BAHRN-20.00W is a VBG (Volume Bragg Grating) wavelength-stabilized fiber-coupled laser diode delivering 20W of Continuous Wave (CW) output power at a precisely locked center wavelength of 878.6nm (±1nm). VBG stabilization eliminates the broad, temperature-dependent wavelength drift characteristic of free-running laser diodes — reducing the thermal wavelength shift to just 0.03 nm/°C and the spectral width to 0.5nm FWHM. These parameters are critical for solid-state laser pumping applications, where pump absorption efficiency is strongly dependent on pump wavelength matching to the gain medium absorption peak. At 878.6nm, this module targets the secondary absorption peak of Nd:YAG and Nd:YVO₄ gain crystals — a well-established alternative to the conventional 808nm pump wavelength. Pumping Nd:YAG at 878.6nm provides a key thermally advantageous effect: the quantum defect (the fractional energy loss per photon between pump and laser photon) is significantly lower at 878.6nm than at 808nm, reducing heat generation in the gain crystal per unit of output power and enabling higher average power operation with reduced thermal lensing in high-power solid-state laser systems. The K878BAHRN-20.00W outputs through a large 200μm core, 0.22 NA fiber with SMA905 connector termination, a 1.5-meter pigtail in 3mm loose tubing, and an 88mm minimum bending radius. The SMA905 interface enables direct, tool-free connection to standard laser delivery fibers, solid-state laser pump input ports, and optical test setups. An optional thermistor (Pins 3 & 4) enables closed-loop temperature monitoring of the laser diode package for precise OEM thermal management.