The WTL Source integrates the tunable
laser, which consists of a cooled external-
cavity diode laser (ECDL). The ECDL uses
thermally tuned etalon filters to achieve
single-mode operation at selectable
wavelengths. It has low Relative Intensity
Noise (RIN), a high Side-Mode Suppression
Ratio (SMSR), a narrow linewidth, and
excellent wavelength accuracy.