1. Solar Laser Emission of Light Amplification by Stimulated Radiation
Academia Quantum 2015
Light
Amplification by
Stimulated
Emission of
Radiation

2. Solar Laser research team
Professor
Dawei Liang
(Head of the
research)
Filipe
Gonçalves
(Master student)
Cláudia
Vistas
(Post-Doc
researcher)
Dário
Garcia
(Master
student)
Rochdi Bouadjemine
(PhD Student)
Joana
Almeida
(PhD student)
Mariana
Oliveira
(Master Student)
Solar Laser / Academia Quantum 2015

3. Lasers are everywhere…
Medicine
Laser Guide Star
Space communication
Military
Industry
CLEO/EQEC 2015 trade fair
Solar Laser / Academia Quantum 2015

4. Spectral irradiance (W/m2/µm)
Light Amplification by Stimulated Emission of Radiation
Fonte de bombeamento
Active medium
Active medium
Solar spectrum
1600
1200
800
400
Spectral irradiance (W/m2/µm)
Wavelength λ (µm)
Absorption (cm-1) 8 6 4 2
Adapted from M. Weksler and J. Shwartz, IEEE J. Quantum Electron. 24(6) (1988)
Solar Laser / Academia Quantum 2015

5. Light Amplification by Stimulated Emission of Radiation
Absorption E2
Spontaneous Emission
Population Inversion - - - - - - E1
Active medium
Solar Laser / Academia Quantum 2015

6. Light Amplification by Stimulated Emission of Radiation
Population
Inversion - - - - - - E3 E3 E2 - E2 E1 - - - - - E1
Active medium
Solar Laser / Academia Quantum 2015

7. Light Amplification by Stimulated Emission of Radiation
HR mirror (100%)
PR mirror (<100%)
LASER emission
Non-excited state
Solar Laser / Academia Quantum 2015

8. Solar collection and concentration
Laser head
Heliostat
Positioning system
Solar Laser / Academia Quantum 2015

9. Solar collection and concentration
1 MW solar furnace in PROMES-CRNS
Solar Laser / Academia Quantum 2015

10. Solar collection and concentration
Solar Laser / Academia Quantum 2015

11. Solar laser operation Solar Laser / Academia Quantum 2015
Solar Laser / Academia Quantum 2015

12. First solar pumped laser
C. G. Young, Appl. Opt. 5(6) (1966)
1 W cw Nd:YAG laser
Solar Laser / Academia Quantum 2015

13. Solar laser schemes Solar Laser / Academia Quantum 2015
J. Almeida et al., Laser Phys. 23 (2013).
J. Almeida et al., Laser Technol. 44(7) (2012)
J. Almeida et al., Appl. Opt 54 (8) (2015)
D. Liang et al., Sol. Energ. Mat. Sol. Cells 134 (2015)
Solar Laser / Academia Quantum 2015

14. End-pumping schemes 40 W cw Nd:YAG laser
Laser beam
Output coupler
Concentrated solar radiation
Water out
Fused silica light-guide
Conical cavity
5 mm Nd:YAG crystal
HR for
1064 nm PR
Resonant cavity
(30 mm mm length)
CPC output end
Water in
J. Almeida, et al., Laser Phys. 23 (2013). HR
Nd:YAG crystal
Conical cavity
Light distribution at the focal spot
Light distribution at
D2 = 25 mm cross-section
Conical light-guide
3D-CPC output end
Cooling water
Light distribution at the input face of the Nd:YAG rod
5 mm
Solar pump light from the parabolic mirror
40 W cw Nd:YAG laser
13.9 W/m2 collection efficiency
2.8% slope efficiency
0.15W brightness figure of merit
Solar Laser / Academia Quantum 2015

15. End-pumping schemes July 2014 Solar Laser / Academia Quantum 2015
Parabolic mirror
Power meter
Output coupler
Conical lens
Nd:YAG rod
Conical cavity
Water outlet
Water outlet
J. Almeida et al., Appl. Opt 54 (8) (2015)
1.57
0.00
W/mm3
Absorbed pump flux distribution
Pabs =208W
Solar Laser / Academia Quantum 2015

16. 56 W cw Nd:YAG solar laser by a heliostat – parabolic mirror system
End-pumping schemes
56 W cw Nd:YAG laser
21.1 W/m2 collection efficiency
4.9 % slope efficiency
0.028 W brightness figure of merit
J. Almeida et al., Appl. Opt 54 (8) (2015)
56 W cw Nd:YAG solar laser by a heliostat – parabolic mirror system
CLEO / EQEC 2015

17. Uniform absorbed pump distribution along the rod
Sept. 2011
Rear mirror
Nd:YAG laser head
Water supply
Pump cavity
Output
mirror
Fused silica
light guide
Side-pumping schemes
J. Almeida et al., Laser Technol. 44(7) (2012)
Light-guide output end
Concentrated
solar radiation
22mm
14mm
Pump light
distribution
Water-flooded
2D-CPC
pump cavity
120mm
Nd:YAG crystal
light guide
Uniform absorbed pump distribution along the rod
30mm
4mm
Water-flooded 2D-CPC cavity
Nd:YAG rod
Solar Laser / Academia Quantum 2015

18. (1.6 m away from the output mirror)
Side-pumping schemes
J. Almeida et al., Laser Technol. 44(7) (2012)
27 W cw Nd:YAG laser
14.6mm
13.8mm
Laser beam profile
(1.6 m away from the output mirror)
9.6 W/m2 collection efficiency
2.0% slope efficiency
0.29 W brightness figure of merit
Solar Laser / Academia Quantum 2015

19. 4 W brightness figure of merit
Side-pumping schemes
Nd:YAG rod
Water in
Concentrated solar radiation
Rectangular
fused silica light guide
Water out
2D-CPC concentrator
V-shaped pump cavity
D. Liang et al., Sol. Energ. Mat. Sol. Cells 134 (2015)
4 W brightness figure of merit
Solar Laser / Academia Quantum 2015

20. Solar lasers – Motivation and Applications
Compared to electrically powered lasers, solar laser is simpler and more reliable due to the elimination of the electrical power generation and conditioning equipments.
Solar energy is a natural choice in places where sun is abundant and other energy sources are scarce
In Portugal…
FCT-UNL
Solar Laser / Academia Quantum 2015

21. Deep space communication
Solar lasers – Motivation and Applications
Space to earth power transmission
Orbital space debris removal
Deep space communication
This technology is particularly attractive for space-based applications where extended run times are required and where compactness, reliability, and efficiency are critical.
As solar energy is the main continuous energy source in space, it can be used to pump solid-state lasers
Solar Laser / Academia Quantum 2015

22. Magnesium – hydrogen renewable energy cycle
Solar lasers – Motivation and Applications
Solar-pumped laser
H2 fuel cells H2 +
½ O2
(combustion) +
86 kcal + Mg
Mg fuel cells
Mg engines
MgO
4000 K
H O 2 +
Magnesium – hydrogen renewable energy cycle Mg
850 K Mg Mg
Mg resource in ocean: 1800 trillion tons
T. Yabe et. al., Appl. Phys Lett. 90(26) (2007)
Solar Laser / Academia Quantum 2015

23. I wish I had a solar-pumped laser
You wish!!
THANK YOU!!!