Introduction to Diode Pumped Alkali vapor Laser -DPAL
Lin Li Institute of Electronics, Chinese
Academy of Sciences Rongqing Tan
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Laser-Light Amplification by Stimulated
Emission of Radiation
Properties:
Monochromatic
Directional
Coherent
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Applications
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• Industry (cutting and welding)
• Military (marking targets , measuring range and speed )
• Research (laser cooling)
• Others (barcode scanners, holographic laser projection)
Laser Components
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Gain medium
Pump energy
Optical cavity
Type Typical Wavelength
Solid state lasers Neodymium-YAG 1.064µm
Gas lasers CO2 lasers 10.6µm
Semiconductor lasers Diode lasers 375-3500nm
Chemical lasers HF lasers 2.6-3.3nm
Types of Lasers
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New type of lasers
In recent years, with the development of diode lasers, there are many new classes of laser devices using diode lasers as pump energy, such as DPSSL (Diode Pumped Solid State Laser), DPAL (Diode Pumped Alkali Vapor Laser).
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People are always looking for lasers with high efficiency, good beam quality, duration etc.
First DPAL by Lawrence Livemore National Laboratory
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Alkali D1 line(nm) D2 line(nm) ΔE(cm-1) QE(%)
Li 670.98 670.96 0.34 99.997
Na 589.76 589.16 17.2 99.898
K 770.11 766.70 57.7 99.557
Rb 794.98 780.25 237.9 98.147
Cs 894.59 852.35 554.1 95.278
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Alkali earth metals Alkali Quantum Efficiencies
Properties of Alkali metals
Einstein was awarded the
Nobel Prize for his discovery and
interpretation of the formula -
E=mc2 - right?
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Wrong
Photoelectric effect
E=h
=h
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Light consists of photons, each with discrete quantum of energy proportional to their wavelength.
2S1/2
2P3/2
D2 line pump
D1 line laser
2P1/2
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Three energy levels of Rb
Ground state
Pump state
Lasing state
λpump=780 nm λlaser=795 nm
26.23 ns
27.70 ns population inversion
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DPAL configuration designed by IECAS
Polarization Beam Splitter
Commercial laser diode
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Single Emitter
Single Bars
Stacked Array
Experiment
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Simulation from Zemax
Beam shaping
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Output power versus incident pump power Maximum output power is 2.8 W Optical-to-optical efficiency is 21%
Light spot of Rb laser
Experiment result
Conclusion
1 DPAL is a new class of lasers with the advantage of high quantum efficiency, good beam quality and less thermal effect.
2 Using fluid medium to improve the efficiency and output laser power.
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Reference 1 Laser-Wikipedia
2 How a Laser Workshttp://muldoonshealthphysicspage.com/how_a_laser_works.htm
3 http://en.wikipedia.org/wiki/Photoelectric_effect
4 SCI FI SCIENCE
http://science.discovery.com/tv-shows/sci-fi-science/videos/sci-fi-science-using-laser-beams.htm
5 Focus: Landmarks: Laser Cooling of Atoms
6 Thesis: BROADBAND PUMPING EFFECTS ON THE DIODE PUMPED
7 Thesis: Theoretical investigation on diode pumped rubidium vapor laser
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