Criteria of optical quality of Cr/sup 4+/:Mg/sub 2/SiO/sub 4/ laser crystals

• Published in: CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005 p. 318
• Main Authors: Lebedev, V.F., Tenyakov, S.Yu, Gaister, A.V., Subbotin, K.A., Zharikov, E.V., Ivanov, A.A.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2005
• Subjects: Absorption; Abstracts; Chromium; Crystals; Electrons; Power generation; Power lasers
• ISBN: 9780780389748; 0780389743
• DOI: 10.1109/CLEOE.2005.1568101

Optical quality of forsterite crystals (Cr/sup 4+/:Mg/sub 2/SiO/sub 4/), which are widely used as active media of femtoseconds lasers, is commonly determined by the parameter FOM=/spl alpha//sub 1064///spl alpha//sub 1250/, where /spl alpha//sub 1064/ is absorption of the crystal at the pump wavelength (1064 nm) and /spl alpha//sub 1250/ is absorption at the laser emission wavelength (1250 nm). FOM is not usually high enough (12-40). However, even for such values of FOM it is hardly measurable by standard techniques. We propose other, more convenient techniques for evaluation of FOM. Parasitic absorption at the laser emission wavelength, which limiting FOM, consists of the superposition of absorption edge of Cr/sup 4+/ and absorption of Cr/sup 2+/ ions. Wide absorption bands of Cr/sup 2+/ ions which correspond to /sup 5/E-/sup 3/T/sub 1/ transition, have the maxima at 1400 nm (E/spl par/b) and 1700 nm (E/spl par/c). The latter band (/spl alpha//sub 1700/) is essentially stronger and suitable for exact detection. Moreover, in the case of this band there do not overlaps with other absorption bands. So, we can modify the parameter FOM to the parameter FOM'=/spl alpha//sub 1064///spl alpha//sub 1700/.