Co2+:MgAI2O4 (or Co2+:Spinel Crystal) is a relatively new material for saturable absorber passive Q-switching in lasers emitting from 1.2 to 1.6 microns, in particular, for eye-safe 1.54 卩 m Englass laser. High absorption cross section of 3.5 x 10-19 cm2 permits Q-switching of Englass laser without intracavity focusing both with flash lamp and diode-laser pumping. Negligible excited-state absorption results in high contrast of Q-switch, i.e. the ratio of initial (small signal) to saturated absorption is higher than 10. Finally, excellent optical, mechanical, and thermal properties of the crystal give an opportunity to design compact and reliable laser sources with this passive Q-switch. It has useful absorption that covers 1.2 to 1.6 micron laser transitions. Spinel is a hard, stable crystal that polished well. Wavelength range is from 1000nm to 1450nm. Absorption cross-section is 3.5x10-19 cm2@ 1540 nm.

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Protective chamfers


Wavefront Distortion

〈入/10 @ 632.8 nm

Dimensional Tolerances

+0.0 mm/-0.2 mm

Parallelism error

w 20 arcsec


w 5 arcmin

Surface Quality



<0.1 mm @ 45deg

AR Coating Reflectivity

w0,2% @ 1540 nm