Low-power-threshold xenon plasma excitation and sustenance based on a temperature-controlled semiconductor laser

Laser-sustained plasma (LSP) represents a high-brightness, broadband light source with promising applications in industrial inspection. However, semiconductor lasers encounter limitations such as wavelength drift and inferior beam quality in LSP contexts. This work presents a 976 nm semiconductor laser system incorporating high-precision temperature control via a thermoelectric cooler, along with an optical pathway utilizing aspheric lenses optimized in Zemax, achieving a focused spot radius of 43 µm. Experimental results demonstrate linear wavelength tuning with temperature (0.42 nm/°C) and current (0.66 nm/A), enabling effective alignment with xenon absorption lines. In xenon plasma experiments, an excitation power density of 1.29×10⁶<i>W</i>/<i>c</i><i>m</i>² and a sustained power density as low as 6.71×10⁵<i>W</i>/<i>c</i><i>m</i>² were attained, significantly lower than those reported in conventional systems. Meanwhile, the plasma exhibited a teardrop-like profile and emitted a broad spectrum spanning 200-2000 nm. This study offers a technical route for realizing low-cost, compact LSP light sources.