Forsterite, also known as magnesium olivine, is a laser active crystal that is commonly used in solid-state lasers. Forsterite has a orthorhombic crystal structure and is doped with chromium ions, which allow it to amplify light through stimulated emission.
One of the main advantages of forsterite as a laser active crystal is its ability to generate laser emissions at a wavelength of 1.3 microns, which is in the eye-safe region and makes it suitable for military and remote sensing applications. Forsterite lasers can also be mode-locked to generate ultra-short pulses in the picosecond or femtosecond range.
Another advantage of forsterite as a laser active crystal is its broad emission bandwidth, which allows it to generate laser emissions at multiple wavelengths simultaneously. This makes it suitable for applications such as spectroscopy and microscopy, where multiple wavelengths are required.
Forsterite has a relatively low thermal conductivity, which can lead to thermal effects such as thermal lensing and reduced efficiency at high pump powers. However, forsterite lasers can be designed to minimize these effects and optimize their performance for specific applications.
PHYSICAL AND OPTICAL PROPERTIES:
|Cr dopant concentration, at.%||0.05 ÷ 0.50|
|Lattice space parameters, Å||a = 4.77; b = 10.28; c = 6.00|
|Refractive indexes||ng = 1.670; nm = 1.651; np = 1.635|
|Thermal expansion coefficient||9.5 x 10-6 x °K-1|
|Thermal conductivity, W x cm-1 x °K-1||0.08|
|Stimulated emission cross section, cm-2||1.44 x 10-19|
|Relaxation time of terminal lasing level, ps||< 10|
|Radiative lifetime, µs||25|
|Spontaneous fluorescence, µs||2.7|
|Absorption loss at 1230 nm, cm-1||0.007 - 0.060|
|Absorption coefficient at 1064 nm, cm-1||0.7 - 3.0|
SPECTROSCOPIC AND LASER PROPERTIES:
|Major pumping bands, nm||850 - 1200; 600 - 850; 350 - 550|
|Fluorescence band, nm||680 - 1400|
|Fluorescence lifetime at 25°C, µs||< 3|
|Lasing wavelength (center)||1235 nm (pulsed), 1244 nm (CW)|
|Spectral bandwidth||30 nm (pulsed), 12 nm (CW)|
|Typical slope efficiency||23% (pulsed), 38% (CW)|
|Tuning range, nm||1130 - 1348|
|Gain cross section, cm2||< 1.45 x 10-19|
Rods with round cross-sections and slabs are manufactured
|Diameter, mm||(4 ÷ 10) ± 0.1|
|Length, mm||(60 ÷ 110) ± 0.6|
|Surface quality, scratch/dig||10 - 5|
|Orientation tolerance||< 5°|