“Stealth Scripts”: Ultrashort Pulse Laser Luminescent Microscale Encoding of Bulk Diamonds via Ultrafast Multi-Scale Atomistic Structural Transformations

Abstract

The ultrashort-laser photoexcitation and structural modification of buried atomistic optical impurity centers in crystalline diamonds are the key enabling processes in the fabrication of ultrasensitive robust spectroscopic probes of electrical, magnetic, stress, temperature fields, and single-photon nanophotonic devices, as well as in “stealth” luminescent nano/microscale encoding in natural diamonds for their commercial tracing. Despite recent remarkable advances in ultrashort-laser predetermined generation of primitive optical centers in diamonds even on the single-center level, the underlying multi-scale basic processes, rather similar to other semiconductors and dielectrics, are almost uncovered due to the multitude of the involved multi-scale ultrafast and spatially inhomogeneous optical, electronic, thermal, and structural elementary events. We enlighten non-linear wavelength-, polarization-, intensity-, pulsewidth-, and focusing-dependent photoexcitation and energy deposition mechanisms in diamonds, coupled to the propagation of ultrashort laser pulses and ultrafast off-focus energy transport by electron–hole plasma, transient plasma- and hot-phonon-induced stress generation and the resulting variety of diverse structural atomistic modifications in the diamond lattice. Our findings pave the way for new forthcoming groundbreaking experiments and comprehensive enlightening two-temperature and/or atomistic modeling both in diamonds and other semiconductor/dielectric materials, as well as innovative technological breakthroughs in the field of single-photon source fabrication and “stealth” luminescent nano/microencoding in bulk diamonds for their commercial tracing.

Multi-Parametric Birefringence Control in Ultrashort-Pulse Laser-Inscribed Nanolattices in Fluorite

“…This was effective over the entire energy range and was more distinct at higher energies. This was consistent with the previous lattice-related observations of stronger etching in bulk-fused silica for the 1 ps laser pulse nanopatterning [ 24 ] and of ≈1 ps electron-ion thermalization in dielectrics [ 19 , 25 ]. The non-optical, lattice-related reason for this pulsewidth effect among the possible consequent optical, electronic, plasmonic, lattice and material transport phenomena could be illustrated by the corresponding weak, even and almost constant dependences T (τ) over the entire energy range ( Figure 2 b).…”

“…The intriguing issue of ultrashort-pulse laser inscription is the driving force for nanoscale material transport in the separate birefringent nanolattices and their bulk arrays. This could be either laser ablation with the formation of nano- [ 17 ] and microcavities [ 13 ] or the drift of charged and neutral point defects in transient electron-hole plasma-induced electrical fields of dynamically curved energy bands [ 26 ] and fields of excited hot acoustic phonons [ 19 , 27 ] (local mechanical stresses). In the first case, in fluorite—both calcium Ca and fluorine F—chemical components should be depleted in the ablation zone [ 28 ].…”

“…Simultaneously, laser exposure was varied in all these regimes to reveal the accumulative structural changes inside fluorite independently of the filamentation [ 30 ]. Meanwhile, laser exposure-dependent atomistic damage could decrease the filamentation threshold energy, as demonstrated in [ 19 ]. The corresponding diffraction images and their 2D Fast Fourier-Transform (FFT) spectra are presented in Figure 6 , characterizing both the filamentary conical emission (radial ring-like patterns both in the images and spectra) and diagonal FFT peaks at the higher N, implying some periodicity in diffraction patterns and the underlying focal or filamentary material structures.…”

“…Moreover, the fundamental self-organization mechanism of such birefringent nanolattices is still questionable, undermining either ablative [ 11 ] or point-defect [ 14 ] material transport. In the latter case, just a few classes of materials—silicates, halogenides [ 18 ] and simple monoelemental substances (e.g., carbon in diamond [ 19 ])—support Frenkel “interstitial-vacancy” pair formation, involving oxygen, halogen and related atoms, respectively. Hence, the understanding of the chemical origin of the laser inscription process is the key issue in the harnessing of this technology for the other classes of transparent dielectric materials.…”

Intrapulse Correlated Dynamics of Self-Phase Modulation and Spontaneous Raman Scattering in Synthetic Diamond Excited and Probed by Positively Chirped Ultrashort Laser Pulses

“…Specifically, in diamonds, in the last decade, ultrashort-pulse laser inscription has been utilized for the fabrication of waveguides [19], single-photon sources based on separate optically active color centers [20,21] and photoluminescent encoding [22,23]. Special attention was focused on the identification of laser filamentation regimes at tight (high-NA) focusing as a function of diamond purity [23], laser wavelength, pulsewidth and polarization [17,24] and the arrangement of laser polarization regarding high-symmetry directions in diamond samples [24,25]. Ultrashort-pulse laser filamentation was characterized in terms of electron-hole plasma dynamics, with near-critical plasma working in the material as a defocusing force for the arrest of Kerr self-focusing beam collapse [3].…”