Jens Klein

Electromagnetically induced transparency and retrieval of light pulses in a Λ-type and a V-type level scheme in Pr3+:Y2SiO5

We examine electromagnetically induced transparency (EIT), the optical preparation of persistent nuclear spin coherences and the retrieval of light pulses both in a Λ-type and a V-type coupling scheme in a Pr3+:Y2SiO5 crystal, cooled to cryogenic temperatures. The medium is prepared by optical pumping and spectral hole burning, creating a spectrally isolated Λ-type and a V-type system within the inhomogeneous bandwidth of the 3H4 ↔ 1D2 transition of the Pr3+ ions. By EIT, in the Λ-type scheme we drive a nuclear spin coherence between the ground-state hyperfine levels, while in the V-type scheme we drive a coherence between the excited-state hyperfine levels. We observe the cancellation of absorption due to EIT and the retrieval of light pulses in both level schemes. This also permits the determination of dephasing times of the nuclear spin coherence, either in the ground state or the optically excited state.

Rapid adiabatic passage in a Pr3+:Y2SiO5 crystal

We report on rapid adiabatic passage (RAP) in a Pr3+:Y2SiO5 crystal, cooled to cryogenic temperatures. The medium is prepared by optical pumping and spectral hole burning, creating a spectrally isolated two-level system within the inhomogeneous bandwidth of the 3H4 → 1D2 transition of the Pr3+ ions. A chirped laser pulse drives a RAP process in the medium, i.e. inverts the initial population distribution. We study the properties and dynamics of RAP by means of fluorescence detection, absorption spectroscopy and amplified spontaneous emission. Time-resolved absorption measurements serve to monitor the adiabatic population dynamics during the excitation process. In addition, we compare the results with coherent excitation at fixed laser frequency detuned from resonance, i.e. coherent population return (CPR).

Robust Population Transfer by Stimulated Raman Adiabatic Passage in a Pr{sup 3+}:Y{sub 2}SiO{sub 5} Crystal

We report on the experimental implementation of stimulated Raman adiabatic passage (STIRAP) in a Pr3+:Y2SiO5 crystal. Our data provide clear and striking proof for nearly complete population inversion between hyperfine levels in the Pr3+ ions. The transfer efficiency was monitored by absorption spectroscopy. Time-resolved absorption measurements serve to monitor the adiabatic population dynamics during the STIRAP process. Efficient transfer is observed for negative pulse delays (STIRAP), as well as for positive delays. We identify the latter by an alternative adiabatic passage process.