Fig. 1. Distributions of electronic energy loss as a function of depth for LiNbO3 crystals irradiated with (a) 49.7 MeV Kr22+, (b) 358.0 MeV Ni19+, (c) 30.0 MeV Cl5+ and (d) 30.0 MeV Si5+, as simulated using SRIM 2013.

Fig. 2. (a) Dark-mode spectra of Si5+-irradiated LiNbO3 crystals measured by a 633 nm laser under TE polarization; the filled circle in the spectrum indicates the refractive index in the sample surface region. (b-e) Schematic diagrams of the irradiation damage (i.e., refractive index) distributions of LiNbO3 crystals corresponding to different Si5+ irradiation conditions.

Fig. 3. Under different ion irradiation conditions, corresponding dark-mode spectra of LiNbO3 crystals measured by a 633 nm laser under (a-d) TE polarization and (e-h) TM polarization; ordinary and extraordinary refractive indices of the surface regions of swift-ion-irradiated LiNbO3 crystals measured by (i) 633 nm and (j) 1539 nm lasers.

Fig. 4. Bright-field cross-sectional TEM images and FFT patterns of (a) the virgin sample and (b-n) latent tracks with different morphologies in ion-irradiated samples corresponding to different ion velocities and electronic energy losses. The peak values of atomic temperature and energy deposition calculated by the iTS model are also indicated.

Fig. 5. (a) Temperature-dependent thermal conductivities and specific heat coefficients of the LiNbO3 atomic subsystem used for iTS model calculations [35], [36], [37], [38], [39], [40], [41]. (b) Absorption radius αe of the LiNbO3 crystal for energy deposition via electronic energy loss as a function of ion velocity. (c) Density distribution of the energy deposited into the electronic subsystem via 1.45 MeV/u ion irradiation with an dE/dxele of 11.8 keV/nm. The fraction of energy deposited into the electronic subsystem versus radius is also shown in the inset. (d) Irradiation energy deposition and subsequent energy exchange between the electronic and atomic subsystems calculated by the iTS model. (e, f) Energy transferred to atoms and corresponding evolution of atomic temperature at different radii versus time.

Fig. 6. (a, b) Atomic temperature evolution and corresponding energy deposition to atoms under ion irradiation conditions with different ion velocities and electronic energy losses. (c, d) Schematic diagrams of the damage morphology evolution in different energy deposition and atomic temperature regions induced by swift ion irradiation.