Stationary and coherent spectroscopy of ¹⁶⁷Er³⁺ in waveguides in ⁷LiYF₄ crystal

Abstract

Abstract.We have conducted a spectroscopic investigation of 167 Er 3+ ions in optical waveguides on an optical transition between the hyperfine sublevels of 4 I15/2 and 4 I9/2 multiplets. Waveguides with diameters ranging from 20 to 100 μm were produced in the crystal by a femtosecond laser using the depressed-cladding approach. The spectroscopy results of 167 Er 3+ ions inside the waveguides show additional broadening and an overall shifts of the spectra compared to the bulk spectrum of ions. The sign of the observed frequency shift depends on the diameter of the specific waveguide. We have also observed a two-pulse photon echo in several waveguides. The acquired results show the possibility for integrated quantum schemes in rare-earth ions doped crystals.Development of optical quantum technologies including optical processors and quantum repeaters is accompanied by the increased attention to their subsequent realization in optical integral schemes. That means that experimental development of integral quantum memories in such schemes is also necessary. Multi-atomic systems can serve as active media for such experiments, such systems include crystals that often have longer quantum coherence times. So waveguides in crystals doped with rare-earth ions are of great interest especially those combinations of rare-earth ion and crystal matrix that exhibit desirable spectroscopic parameters for quantum memory realization. In our previous work we studied the 167 30, 50, 75 and 100 μm and were produced by a femtosecond laser using the depressedcladding approach with 515 nm wavelength. We carried out a high-resolution spectroscopy of 167 Er 3+ ions in different waveguides at 4 K temperature. Fig. 1a shows three of the resulting