A cobalt-doped transparent glass ceramic saturable absorber Q-switch for a LD pumped Yb3+/Er3+ glass microchip laser

Structural and Optical Properties of Co2+-Doped PbSe Nanocrystals in Chalcogeneide Glass Matrix

“…The observed structures in the optical absorption spectra of PbSe:Co 2+ system, analyzed in this study, are similar to those observed in other materials, both in bulk as well as in the nanocrystalline form, ,− ,,,, when the Co 2+ ion is in the tetrahedral site, and are not consistent with the optical properties of the Co 2+ ion when it is in the octahedral sites. , The crystal field strength Δ for the tetrahedral site is lower than the charged ion in the octrahedral site (Δ ( Td ) ≈ 0.5 Δ ( Oh ) ). , This leads to a big change in the optical transitions’ energy observed in the optical absorption spectra …”

“…In the tetrahedral sites, the ground level 4 F of a free ion Co 2+ is split into three levels, 4 T 1 , 4 T 2 , and 4 A 2 , by the crystal field (Figure A). The absorption spectra in the visible light region (Figure B) present a component close to 587 nm assigned to the spin- and electric-dipole-allowed 4 A 2 (F) → 4 T 1 (P) Co 2+ ligand transition. ,, Bands close to 530, 639, and 650 nm are due to three spin-forbidden transitions. These bands are assigned to 4 A 2 (F) → 2 A 1 (G), 4 A 2 (F) → 2 T 1 (G), and 4 A 2 (F) → 2 E­(G) transitions, respectively, according to the Tanabe–Sugano diagram of d 7 ( T d ) for C/B = 4.5. ,, Their transition energies can be well described by a Racah parameter, B = 788.2 cm –1 , and by crystal-field splitting, Δ = 3882.9 cm –1 , and they are shown by spots at the Δ /B = 4.93 value in Figure B.…”

Nonlinear Absorption of Submicrometer Grain‐Size Cobalt‐Doped Magnesium Aluminate Transparent Ceramics

“…In the majority of cases, Co:MgAl 2 O 4 used as a saturable absorber is produced as single crystals, for instance by the Verneuil method or Czochralski method . Glass‐ceramics with cobalt‐doped spinel nanocrystals embedded in the glass matrix were proposed as an alternative . As discussed in the already available studies, ceramic technology offers many structural, functional, and economic advantages over mostly used single‐crystalline preparation techniques.…”

“…3,4 Glass-ceramics with cobalt-doped spinel nanocrystals embedded in the glass matrix were proposed as an alternative. 5,6 As discussed in the already available studies, 7,8 ceramic technology offers many structural, functional, and economic advantages over mostly used single-crystalline preparation techniques. The successful use of polycrystalline ceramic laser materials was reported broadly in the literature.…”

Transition metals as optically active dopants in glass-ceramics

“…This is the case of[4] Co 2+ for which the broadband absorption overlaps the ~1540 nm emission of Er 3+ -doped in crystal and glass lasers. TGCs based on different nanosized spinels doped with Co 2+ were developed in aluminosilicate systems with interesting performances 92,93,94,95. For instance, a saturable absorption has been reported for TGCs containing both Co 2+ :ß-Zn2SiO4 and Co 2+ :ZnO NCs 91.…”