Tailorable dispersion in a four-wave mixing laser

Abstract

We present experimental results demonstrating controllable dispersion in a ring laser by monitoring the lasing-frequency response to cavity-length variations. Pumping on an N-type level configuration in 87 Rb, we tailor the intra-cavity dispersion slope by varying experimental parameters such as pump-laser frequency, atomic density, and pump power. As a result, we can tune the pulling factor (PF), i.e. the ratio of the laser frequency shift to the empty cavity frequency shift, of our laser by more than an order of magnitude.

Dispersion-enhanced tunability of the laser-frequency response to the cavity-length change

“…For active cavities, Yablon et al [11] inferred a PF∼ 190 via analysis of the lasing linewidth. The increased stability regime (PF< 1) was demonstrated in lasing [12] cavities with the smallest being PF= 1/663 [13]. Superradiant ("bad-cavity") lasers, where an atomic gain line is much narrower than a cavity linewidth, exhibit ultra low PF< 10 −6 [14,15].…”

“…3. The theory and preliminary experimental study of this arrangement are covered in references [12,17,18]. The strong pumping field Ω 1 creates a transmission line for the field α due to electromagnetically induced transparency.…”

“…Our lasing cavity is similar to the one used in [12]. The ring cavity is made of two polarizing beam splitters (PBS) and two flat mirrors.…”

“…4 cannot explain the arching behavior, since it does not account for the dependence of the dispersion on the lasing power. However, a more complete model which solves density matrix equations of the N-level scheme predicted such a possibility [12].…”