Author (Your Name)

Kate JensenFollow

Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Physics and Astronomy Dept.


Professor Duncan Tate


Resonant optical excitation of high-lying Rydberg states in room temperature 85Rb was investigated using light from two homemade external cavity diode lasers (ECDL). This was done using a ladder schema of the Electromagnetically Induced Transparency (EIT) technique. The approximate EIT wavelengths used were 780 nm (the probe beam) to provide step-wise excitation of valence rubidium electrons from the 5S1/2 → 5P3/2 tran- sition, and then 482 nm (the coupling beam) to excite from the 5P3/2 state to a high-lying Rydberg nD state with an orbital angular momentum = 2. Successful excitation of the Rydberg states was observed using Frequency Modulation Spectroscopy (FMS). Also included in this discussion is a description of efforts made to maximize the sensitivity of the FMS technique throughout this study.

Similar work has been done in the past for Rb atoms but have employed very powerful commercial laser systems (for instance, those made by the German company Toptica) which typically exceed $100,000 in price (depending on power) and hence makes such research financially inaccessible in many institutions. The novel aspect of this research project is the use of homemade diodes which were assembled for a fraction of the price. Higher-n Rydberg transitions are relatively improbable quantum-mechanically; conse- quently, the 482 nm coupling beam at the highest power possible to boost the chances of this transition occurring which requires particular attention when using self-built cavity diode lasers. Here we attempt to demonstrate that the signal from a combination of EIT and FMS techniques can be equally strong as when using expensive commercial laser systems with the appropriate experimental methods.


External Cavity Diode Laser, Electromagnetically Induced Transparency, Frequency Modulation Spectroscopy, Signal Noise Ratio