Modulators using atomic systems are often limited in speed by the rate of spontaneous emission. One approach for overcoming this limit is to make use of a buffer gas such as Ethane, which causes rapid fine structure mixing of the P1/2 and P3/2 states, and broadens the absorption spectra of the D1 and D2 lines in alkali atoms. Employing this effect, we show that one can achieve high speed modulation using ladder transitions in Rubidium. We demonstrate a 100-fold increase, due to the addition of the buffer gas, in the modulation bandwidth using the 5S-5P-5D cascade system. The observed bandwidth of ∼200 MHz is within a factor of 2.5 of the upper bound of ∼0.51 GHz for the system used, and is limited by various practical constraints in our experiment. We also present numerical simulations for the system and predict that a much higher modulation speed should be achievable under suitable conditions. In combination with a tapered nano fiber or a SiN waveguide, it has the potential to be used for high-speed, low-power all-optical modulation.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics