Vis-NIR spectral flatness improvement for Laser-Driven Light Sources (LDLS™)

The demand for high brightness, stable, long-life and broadband light sources has been rising continuously in advanced applications for semiconductor metrology, sensor calibrations, and life sciences imaging. Laser-Driven Light Sources (LDLS (TM)) are capable of delivering super-high brightness and stable radiation over long lifetimes. LDLS sources use high power diode lasers to energize high-intensity xenon (Xe) plasma which produces broadband radiation from 170nm to 2400nm. The LDLS spectrum has several spectral peaks located near 826nm, 885nm, and 920nm, similar to regular Xe short arc lamps. Those peaks, when compared with lower emission wavelengths, can reduce the dynamic range of broadband spectral measurements. In this paper, the application of a spectral flattening filter for LDLS sources is presented. With optimized coupling optical design, the output power and spectral performance for the LDLS under different fiber coupling conditions have been compared and analyzed. Measurement results show the coupled flux could reach 83mW with a 600 mu m diameter fiber, and the high Xe peaks near 826nm, 885nm, and 920nm have been suppressed successfully.