Rovibrational optical cooling of $Rb_{2}$ in a supersonic beam*

In this work, we propose to optically cool the rotation and the vibration of $Rb_{2}$ molecules in a supersonic beam by applying a broadband light source. Such source consists of a tapered amplifier laser with frequency-shifted feedback, around 682 nm, which can drive transitions from $\nu_{x}, J_{x}$ $X^{1}\Sigma_{g}^{+}$ ground state to the $b^{1}\Pi_{u}$ excited potential. The spectrum of our source is such that the $\nu_{x}, J_{x} = 0$ $X^{1}\Sigma_{g}^{+}$ ground state will be a dark state. The molecules will be observed by photoionization technique, through transitions from the $\nu_{x}, J_{x}$ to $\nu, J_{x}$ of the $b^{1}\Pi_{u}$ potential using a CW diode laser, and then photoionized by a 532 nm pulsed laser. Such technique will allow us to resolve the rotational distribution of the $\nu_{x}=0$. Theoretical simulations indicate that we should be able to perform the rovibrational cooling in less than 300 $\mu$s.