Cr GSGG Passive Q-Switch Crystal

18 Jul 2019

Description

Cr:GSGG crystal—a crystal which shows high efficiency and high reliability.

Cr⁴⁺: GSGG has been utilized for the first time to provide a saturable absorber Q-switch for the ruby laser. Single output pulse operation (100 mJ and 27 ns duration) with efficiencies relative to the free-running ruby laser operation of 25-30% was routinely obtained. The crystalline material GSGG:Cr³⁺ is currently of interest as a broad-band, room temperature laser material. The small separation between the ⁴T2 and ²E electronic levels of Cr³⁺ in the system can result in interesting spectroscopic behaviour. People have investigated the temperature dependence of the CW and transient luminescence, and have found it to be consistent with a model for the dominant Cr³⁺ site in which the lowest energy ²E and ⁴T2 levels are approximately coincident in energy at low temperature.

Gadolinium scandium gallium garnet(GSGG) codoped with Cr is a laser material with high efficiency. An electro-optic shutter element was first utilized to provide Q-switched operation of the ruby laser. Passive Q-switched ruby lasers were achieved with saturable dye absorbers and colored glass (compounds of selenium and cadmium sulfide. Recently the operational characteristics of a dye Q-switch for a pulsed ruby laser was still studied for application in underwater holography. However, the dye Q-switch was limited in durability because of degradation (decomposition) of the dyes and the glass Q-switch was readily damaged. Thus, the tetravalent chromium doped gadolinium scandium gallium garnet Gd₃Sc₂Ga₃O₁₂ (Cr⁴⁺: GSGG) passive Q-switch ruby laser-offers for the first time high reliability, durability and high efficiency.

Parameter

Emission wavelength (nm)	1061.2
Emission cross section (pm2)a	13
R2->Y3 transition linewidth (cm-1)	11.5
Nd3+ fluorescence lifetime (ps) at low concentrations (<1017cm-3 )	273-283
Nd3+ concentration for which lifetime is reduced by 50% (1020 Nd ions cm-3)	5

Optical properties

Refractive index at 1064 nm	1.9424
Index change with temperature, dn/dt,(10-6 k-1)	10.9
Elasto-optic constants
P11	-0.012 ± 0.003
P12	0.019 ± 0.003
P44	-0.0665 ± 0.0013

Thermo-mechanical Properties

Density (g*cm-3)	6.495
Heat capacity (J*g-1*K-1)	0.4029
Thermal conductivity (W*m-1*K-1)	6
Thermal expansion (10-6 K-1)	7.5
Poisson’s ratio	0.28
Young’s modulus (GPa)	210
Fracture toughness (MPa )	1.2
Thermal- stress resistance (W*m-1)b	660

Absorption Spectrum

Room-temperature-absorption-specturm-of-the-Cr4GSGG-crystal

Feature

• High reliability

• High efficiency

• High durability

• Strong and saturable absorption

• Good thermal conductivity

Application

Cr⁴⁺: GSGG used in saturable absorber Q-switch for the ruby laser:

The tetravalent chromium doped gadolinium scandium gallium garnet Gd₃Sc₂Ga₃O₁₂ (Cr^{4 +} : GSGG) passive Q-switch ruby laser-offers for the first time high reliability, durability and high efficiency. Single output pulse operation (100 mJ and 27 ns duration) with efficiencies relative to the free-running ruby laser operation of 25-30% was routinely obtained.