22 May 2019 Description
Yb:CaGdAlO4 (Yb:CALGO)- Yb doped crystals for high power and ultrashort(femtosecond) lasers
Yb-doped CaGdAlO4 crystal (Yb:CALGO) is now recognized to exhibit outstanding properties for the production of high-power and ultra-short laser pulses. It has the broad and smooth emission bandwidth to generate very short pulses (
Yb3+:CaGdAlO4 has been recently demonstrated to be very interesting for the development of diode–pumped short-pulsed modelocked lasers. Compared with Ti: Sapphire crystal（the choice for the development of ultrashort laser system producing very short and powerful pulses using the Chirped Pulse Amplification technique，Since the beginning of the 90’s）,Yb:CALGO can be directly pumped by very efficient and high power semiconductor laser.( Titanium Sapphire crystal pumped by green laser)
Parameter
Material and Specifications
| Doping Concentration |
1-10% |
| Parallelism |
10〞 |
| Perpendicularity |
10ˊ |
| Surface Quality |
20/10 |
| Surface Flatness |
<λ/10@632.8nm |
| Clear Aperture |
>90% |
| Chamfer |
0.1mm@45° |
| Thickness/Diameter Tolerance |
±0.05 mm |
Physical and Chemical Properties
| Formula |
Yb:CaGdAlO4 (Yb:CALGO) |
| Crystal Structure |
Tetragonal K2NiF4 type structure |
| Melting Point |
1840°C |
| Thermal Conductivity/(W·m-1·K-1) |
11.4(undoped)
6.3(2% Yb:CALGO)
5(5% Yb:CALGO) |
| Thermal Shock Resistance(W.m-1/2) |
>4.5 |
| Thermal Expansion /(10-6·K-1 ) |
35 |
Optical and Spectral Properties
| Emission band width* (FWHM) (nm) |
80 |
| Emission Wavelength(nm) |
1018-1052 |
Minimum theoretical
duration (fs) |
14 |
Central emi
ssion peak (nm) |
1050 |
Absorption
(usual pumping) (nm) |
980 |
Emission
cross section(10-20 cm2) |
0.8 |
Fluorescence
lifetime (μs) |
420 |
| σem τ(μscm2) |
336 |
| Quantum Defect |
<0.8% |
Main properties of laser materials involved in the development of femtosecond lasers
| Material |
Emission band
width(FWHM) (nm) |
Minimum theoretical
duration (fs) |
Central emi
ssion peak (nm) |
Absorption
(usual pumping) (nm) |
| Yb:YAG |
9 |
124 |
1031 |
942 |
| Yb:Glass |
35 |
31 |
1020 |
975 |
| Yb:GdCOB |
44 |
26 |
1044 |
976 |
| Yb:BOYS |
60 |
18 |
1025 |
975 |
| Yb:KGW |
25 |
44 |
1023 |
981 |
| Yb:KYW |
24 |
46 |
1025 |
981 |
| Yb:SYS |
73 |
16 |
1040 |
979 |
| Yb:YVO4 |
30 |
36 |
1008 |
984 |
| Yb:CaF2 |
30 |
36 |
1047 |
980 |
| Yb:CALGO |
80 |
14 |
1050 |
980 |
| Material |
Emission
cross section(10-20 cm2) |
Fluorescence
lifetime (μs) |
σem τ(μscm2) |
Thermal conductivity
(undoped)(W/m/K) |
| Yb:YAG |
2.1 |
951 |
1997 |
11 |
| Yb:Glass |
0.05 |
1300 |
65 |
0.8 |
| Yb:GdCOB |
0.35 |
2600 |
910 |
2.1 |
| Yb:BOYS |
0.3 |
1100 |
330 |
1.8 |
| Yb:KGW |
2.8 |
600 |
1680 |
3.3 |
| Yb:KYW |
3 |
600 |
1800 |
3.3 |
| Yb:SYS |
0.44 |
820 |
361 |
2 |
| Yb:YVO4 |
1.25 |
250 |
312 |
5.1 |
| Yb:CaF2 |
0.25 |
2400 |
600 |
9.7 |
| Yb:CALGO |
0.8 |
420 |
336 |
11.4 |
 
Feature
-
High thermal conductivity
-
Large gain bandwidth
-
Broad and smooth emission bandwidth
-
Low refractiveindex-temperature gradient
-
Absorption band is covered by high-power InGaAs laser diodes
Application
-
Solid state femtosecond oscillators
-
Ultrafast solid-state laser
time-resolved spectroscopy, multiphoton imaging, micromachining, refractive surgery, acceleration of particles, X-rays generation, fusion, etc.
modelocked laser
-
BAW device
-
Diode–pumped short-pulsed modelocked lasers
-
Femtosecond lasers technology
-
Bicolor double-pulse regime
Yb:CALGO, it is possible to generate double pulses with different wavelengths, which is to our best knowledge the first demonstration of bicolor femtosecond double-pulse operation. Very broad spectrum has been obtained with a bandwidth greater than 30 nm . The spectrum can be fit with two Gaussians: one centered at 1040 nm with a bandwidth of 21 nm and one centred at 1057 nm with a bandwidth of 10 nm with lower amplitude (60%).
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