We report what is, to the best of our knowledge, the first observation of transient spectral hole burning in erbium-doped fluorozirconate glass around 1.53 μm. Holes deeper than 12% were burnt. A study of the hole width as a function of power density, wavelength, temperature, and erbium concentration has been performed and underlines the role of spectral diffusion. Dynamics of refilling of the holes, involving optical pumping of the long-lived 4I13/2 excited state, was also investigated. The nearly linear temperature dependence of the hole width behaves as reported for other rare-earth ions and is interpreted within the framework of the two-level systems theory. Hole-refilling dynamics has been studied for three different erbium concentrations and is used to interpret the origin of the saturation.
Persistent and time-resolved transient holes were burnt into the
1D2${\ensuremath{\leftarrow}}^{3}$
H4 transition of
Pr3+ and the
5D0${\ensuremath{\leftarrow}}^{7}$
F0 transition of
Eu3+ in silicate glasses. The holewidths were studied as a function of burning-fluence density, wavelength, and temperature between 0.4 and 12 K. Transient holes arising from optical pumping of ground-state nuclear hyperfine levels were found for both ions at T3 K. Their lifetime decreases with increasing temperature. They are accompanied by symmetrically placed antiholes. For
Eu3+, two pairs of antiholes were found which are attributed to the two europium isotopes,
151Eu and
153Eu. For
Pr3+, an additional mechanism leading to persistent hole burning dominates above 3 K. The holewidth follows a ${\mathit{T}}^{(1.3\ifmmode\pm\else\textpm\fi{}0.1)}$ dependence for
Pr3+ and a ${\mathit{T}}^{(1.0\ifmmode\pm\else\textpm\fi{}0.1)}$ dependence for
Eu3+. The temperature dependence is the same as that of the contribution of the two-level systems to the specific heat measured on the same samples and in the same temperature range. The quadrupole splittings of the
7F0 ground state and the crystal-field splittings of the
7F1 and
7F2 levels of
Eu3+ as a function of excitation wavelength indicate that the strength of the noncubic component of the crystal field varies monotonically for excitation across the
5D0${\ensuremath{\leftarrow}}^{7}$
F0 absorption band, falling to zero at the long-wavelength edge. The hole width shows a similar variation with excitation frequency. No influence of the experimental time scale on the hole width was detected for either sample between ${10}^{\mathrm{\ensuremath{-}}2}$ and
102 s.
We reported the first observation of room-temperature persistent spectral hole burning in Sm2+-doped fluoride glass in the last conference [1]. Room-temperature hole burning had been also observed in Sm2+-doped crystals [2]. We found considerable differences in the hole-burning characteristics between Sm2+-doped glasses and Sm2+-doped crystals: The burning-laser-intensity dependence is approximately linear, and no antihole is observed around the hole burned in Sm2+-doped glasses [3]. More detailed experimental studies are needed to clarify the mechanism of the hole burning in this glass and to explore more efficient hole-burning systems. In this paper, we report several experimental results related to wavelength dependence of the hole burning process.
Persistent spectral hole burning is observed in Sm(2+)-doped glasses at room temperature. The holes are burned in the (7)F(0) ? (5)D(0), (5)D(1) lines of the Sm(2+) ions in three kinds of fluoride glass. The dependence of the burning efficiency on the sample and on the burning intensity is measured. The intensity dependence is approximately linear, and no antihole is observed around the burned hole. The hole-burning mechanism is discussed. The temperature dependence of the homogeneous width is also measured.
Persistent spectral holeburning is known to occur in rare-earth doped silica-based glasses,1-3 where the mechanism is attributed to light induced changes in the coupling of tunnelling systems (TLS) which are characteristic of the amorphous state. A number of hole parameters such as lifetime, saturation depth and temperature dependence of the width, can provide important information on the density of states and dynamics of the TLS. We present the first data on spectral holeburning in a rare-earth doped heavy metal fluoride glass (HMF, Rennes) and compare with data obtained on a silicate glass (ED-2, Owens-Illinois). For this study we have chosen the well known 4I9/2 ← → 4F3/2 transition of the Nd3+ ion whose absorption peaks around 870nm (HMF) and 880nm (ED-2). Previous holeburning and photon echo measurements have been reported on the 4I9/2 ← → 4G5/2 transition of the Nd3+ of bulk ED-2 glass4 and on the 4I9/2 ← → 4F3/2 transition of the Nd3' transition of a pure silica fiber.3,5
Long-lived population storage in optically pumped levels of rare-earth ions doped into solids, referred to as persistent spectral hole burning, is of significant fundamental and technological interest. However, the demonstration of deep and persistent holes in rare-earth ion doped amorphous hosts, e.g., glasses, has remained an open challenge for many decades---a fact that motivates our work towards a better understanding of the interaction between impurities and vibrational modes in glasses. Here we report the observation and detailed characterization of such holes in an erbium-doped silica glass fiber cooled to below 1 K. We demonstrate population storage in electronic Zeeman sublevels of the erbium ground state with lifetimes up to 30 seconds and 80% spin polarization. In addition to its fundamental aspect, our investigation reveals a potential technological application of rare-earth ion doped amorphous materials, including at telecommunication wavelength.
Understanding decoherence in cryogenically cooled rare-earth-ion doped glass fibers is of fundamental interest and a prerequisite for applications of these material in quantum information applications. Here we study the coherence properties in a weakly doped erbium silica glass fiber motivated by our recent observation of efficient and long-lived Zeeman sublevel storage in this material and by its potential for applications at telecommunication wavelengths. We analyze photon echo decays as well as the potential mechanisms of spectral diffusion that can be caused by coupling with dynamic disorder modes that are characteristic for glassy hosts, and by the magnetic dipole-dipole interactions between
Er3+ ions. We also investigate the effective linewidth as a function of magnetic field, temperature, and time, and then present a model that describes these experimental observations. We highlight that the operating conditions (0.6 K and 0.05 T) at which we previously observed efficient spectral hole burning coincide with those for narrow linewidths (1 MHz)---an important property for applications that has not been reported before for a rare-earth-ion doped glass.