Speaker
Description
Single-longitudinal-mode (SLM) Raman lasers are emerging as powerful light sources for quantum technologies and optical clock applications due to their linewidth-narrowing and wavelength-shifting capability. Recent work has shown significant narrowing of the pump intrinsic linewidth in Raman lasers through a phonon damping mechanism analogous to linewidth narrowing in Brillouin lasers. However, it has been observed that the frequency noise (FN) is higher than expected. Anomalous noise was observed in a doubly resonant Raman laser, where both the pump and Stokes fields are resonantly enhanced inside the cavity to lower the Raman threshold. Understanding noise-transfer mechanisms is therefore important for designing Raman lasers suitable for low-noise quantum applications.
We present experimental and model studies of pump-noise transfer in a SLM $\mathrm{GdVO_4}$ doubly resonant Raman laser. We measure the Stokes FN as a function of pump intrinsic linewidths to better understand the effect of pump-noise properties on the generated Stokes field. We use a numerical model that takes the measured pump FN and relative intensity noise (RIN) spectra as input, to solve for the Stokes field and phase using the coupled Raman equations. The model includes Raman gain modulation, detuning-dependent intracavity power, and Kerr-induced refractive-index changes. Comparison with experiment shows that a major contributor to the Stokes frequency noise is the transfer of pump frequency noise to RIN in the cavity via frequency modulation to amplitude modulation conversion, which is then coupled into Stokes FN via the Kerr effect. These findings highlight how pump linewidth, cavity linewidths, intracavity power, and output coupling influence noise transfer and provides a way for optimized low-noise doubly resonant Raman laser design.
| I am the presenting author | Yes |
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