Optical coherent transients in ¹⁶⁷Er³⁺ at telecom-band wavelength

We demonstrate optical coherent transients in a Λ-like hyperfine energy-level system of Er167³⁺ in yttrium orthosilicate (Y₂SiO₅) with telecom-band photons at a zero magnetic field. Spectral hole burning was used to study the temperature dependence of the induced spectral antihole. We find that temperatures below 3.0 K suppress population dissipation induced by electron-phonon interactions sufficiently to enable population initialization in the Λ-like system. Further, the pulse area dependence of photoluminescence (PL) from the Λ-like system was measured at 2.2 K. An optical pump power dependence of PL intensity shows Rabi oscillations that contain two full Rabi cycles at the frequency of 2π×810  kHz. A two-pulse photon echo measurement reveals an optical coherence time of 12 μs. To date, this measured optical coherence time is the longest observed for Er³⁺ in solids at zero magnetic field. These findings will facilitate optical coherent manipulation of Λ-like Er167³⁺ electronic states as a quantum memories operating at telecom-band wavelengths.