A technique to fabricate isolated diamond particles with controllably embedded silicon-vacancy (Si-V) colour centres is described. Particle growth and Si doping are performed by microwave plasma-enhanced chemical vapour deposition (CVD) using silane as a source of impurity atoms. The Si-V centres have a strong narrow-band photoluminescence (PL) at room temperature. The dependence of PL intensity of the 738 nm zero-phonon line (ZPL) on silane concentration in the feed-gas mixture exhibits a pronounced maximum. A comparison of the PL and Raman spectra shows that there is an evident correlation between the ZPL intensity and the presence of structural defects and nondiamond carbon phases that act as nonradiative recombination centres suppressing radiative recombination. The results open the door for using the powerful CVD technique for large-scale production of photostable near-infrared single-photon emitters and noncytotoxic biomarkers.

Synthetic high-pressure high-temperature (HPHT) microdiamonds demonstrate strong resonant-like enhancement of the NV⁻ photoluminescence (PL) at unexpectedly low concentration of the substitutional nitrogen atoms (N_S) of 90 ppm, which is significantly smaller than the ∼250 ppm characteristic for conventional HPHT synthesis. The EPR, Raman, and luminescent spectroscopies, including time-resolved PL, provide evidence that this is due to competition between the increase in PL with increasing concentration of the NV⁻ centers and nonradiative deactivation of these centers by defects induced by the N_S in the diamond crystal lattice. It is suggested that the intensity of the NV⁻ center emission can be optimized by the appropriate choice of nitrogen doping concentration which does not substantially disrupt the diamond crystal lattice.

A comparative analysis of the Raman spectra of bulk PbS and PbS nanocrystals with average diameters of 6.6 and 3.8 nm has been performed. It is shown that the bands due to the LO phonons at the Γ...

We report on the development of novel saturable absorbers for erbium lasers based on transparent glass-ceramics (GCs) containing a mixture of cobalt-doped $\beta$-willemite, ${\mathrm{Co}}^{2+}\text{:}\beta \text{-}{\mathrm{Zn}}_2{\mathrm{SiO}}_4$, and zinc oxide, ${\mathrm{Co}}^{2+}\text{:}\mathrm{ZnO}$, nanosized (10–14 nm) crystals. The structure of the parent glass and GCs is studied by x-ray diffraction, differential scanning calorimetry, transmission electron microscopy, and Raman spectroscopy. Variations of absorption spectra with heat-treatment reveal that ${\mathrm{Co}}^{2+}$ ions from the parent glass enter the crystals of ZnO and $\beta$-willemite. GCs are characterized by a broad absorption band due to the ${}^4{\mathrm{A}}_2({}^4\mathrm{F})\to {}^4{\mathrm{T}}_1({}^4\mathrm{F})$ transition of ${\mathrm{Co}}^{2+}$ ions in tetrahedral sites spanning up to $\sim 1.74\mathrm{\mu m}$, relatively low saturation fluence, $F_S=0.75\mathrm{J}/{\mathrm{cm}}^2$ at 1.54 μm, short recovery time, $\tau =830\mathrm{ns}$, and high laser damage threshold, $\sim 14\mathrm{J}/{\mathrm{cm}}^2$. By using the developed GCs in a diode-side-pumped Er, Yb:glass laser, 0.77 mJ/45 ns pulses are generated.