Daniel Thrasher

Comments on “Intensity noise of an injection-locked Ti:sapphire laser: analysis of the phase-noise-to-amplitude-noise conversion”

An analysis showing that phase noise in a master diode laser is converted to amplitude noise in an injection-locked Ti:sapphire power amplifier was recently published [“Intensity noise of an injection-locked Ti:sapphire laser: analysis of the phase-noise-to-amplitude-noise conversion,” J. Opt. Soc. Am. B, 23, 1276–1286 (2006)]. As this analysis might discourage the broad implementation of injection locking, we report amplitude noise and laser linewidth measurements in such a system and note that these lasers have sufficiently low noise to be useful in a wide range of experiments in atomic, molecular, and optical physics. A low-power diode laser is amplified to 1.6 W at 846 nm. Amplitude noise is measured using a high-speed photodiode. Frequency noise is measured relative to a low-noise commercial Ti:sapphire laser using an offset lock and heterodyne technique. Under optimal conditions, the relative rms amplitude noise is 1%. The linewidth of the injection-locked laser is 300 kHz. As others in this field have shown, the amplitude and frequency noise characteristics depend critically on the lock circuit characteristics.