Title :
Saturable absorbers based on impurity and defect centers in crystals
Author :
Demchuk, M.I. ; Kuleshov, N.V. ; Mikhailov, V.P.
Author_Institution :
Inst. of Appl. Phys., Acad. of Sci., Minsk, Byelorussia
fDate :
9/1/1994 12:00:00 AM
Abstract :
Saturation of near-infrared absorption and transmission dynamics are investigated in tetravalent-chromium-doped Gd3Sc2 Ga3O12, Gd3Sc2Al3 O12, and Mg2SiO4 crystals, as well as in reduced SrTiO3 using 20 ps 1.08 μm laser pulses. An absorption cross section of (5±0.5)×10-18 cm2 in garnets and (2.3±0.3)×10-18 cm2 in forsterite is estimated for the 3A 2-3T2 transition of tetrahedral Cr4+. Q-switched and ultra-short pulses are realized in neodymium lasers using chromium-doped crystals as the saturable absorbers. Saturation of free-carrier absorption with ultra-short relaxation time is observed in SrTiO3 at 108-10 10 W/cm2 pump intensities, while at 1010-1011 W/cm2 three-photon interband transitions predominate. The free-carrier absorption cross section is estimated to be (2.7±0.3)×10-18 cm2
Keywords :
chromium; garnets; high-speed optical techniques; impurities; impurity and defect absorption spectra of inorganic solids; infrared spectra of inorganic solids; optical saturable absorption; 1.08 micron; 20 ps; Gd3Sc2Al3O12:Cr; Gd3Sc2Ga3O12:Cr; Mg2SiO4:Cr; Q-switched ultra-short pulses; SrTiO3; defect centers; forsterite; free-carrier absorption cross section; garnets; impurity centers; near-infrared absorption dynamics; near-infrared transmission dynamics; neodymium lasers; reduced crystals; saturable absorbers; tetrahedral Cr4+ transition; tetravalent-chromium-doped crystals; three-photon interband transitions; ultra-short relaxation time; Absorption; Crystals; Garnets; Impurities; Laser transitions; Neodymium; Optical pulse generation; Optical pulses; Pump lasers; Solid lasers;
Journal_Title :
Quantum Electronics, IEEE Journal of
