Chirp-compensated pulsed titanium–sapphire laser system for precision spectroscopy

Active frequency-chirp control for a narrowband pulsed titanium–sapphire laser oscillator–amplifier laser system is demonstrated using an intra-cavity electro-optic modulator, resulting in improved spectral resolution and stability. Beat-note measurements of its output to a continuous-wave laser locked to an optical frequency comb yields an Allan deviation of 5 × 10 − 11 (at 10 s). Correction of residual chirp from a comparison with the fourth-harmonic upconverted pulsed output to a molecular H 2 two-photon resonance delivers a value for the uncertainty contribution due to frequency chirp below the 1.5 × 10 − 10 level.