1. The solid-state laser - A 50 year old light bulb
Fredrik Laurell, Laser Physics group, Applied Physics Department, KTH

2. Lasers - in the Solid State
What ?
How ?
Where and why ?

3. Outline Outline Background and history Diode laser concepts
Compact stable tailored lasers
Diode-pumped Solid-state Lasers
Fiber lasers
Tailoring DPSSL and fiber lasers
Conclusions

4. Basic Laser Laser medium Resonator Pump
Atoms in a matrix Energy diagram for a laser stimulated emission

5. i.e. the concept of Stimulated emission

6. Laser history Einstein introduces quantum transitions
1924 Tolman suggests amplification via stimulated emission
Quantum mechanics, atomic and microwave physics
1954 first MASER
1959 acronym LASER was introduced
Schawlow: ”ruby is not a good laser candidate”
1960 Maiman realize the ruby laser
it is a very unlikely process

7. a ruby rod, mirros deposited on the end-faces and a flash lamp
Maiman had
to fabricate
everything
himself
Absorption and emission for Cr3+

8. What lasers do we have today? Gas lasers Dye lasers
Solid-state lasers;
Ruby, Nd:YAG, Ti-Sapphire
Diode-pumped solid-state lasers
Thin disc laser
Fiber laser
Semiconductor laser
Free electron lasers
...
What lasers do
we have today?

9. Choosing the Laser Medium
Gas
Liquid
Solids
Crystals
Semiconductor
Glass
Fiber
Dye in gelatin
...
Finding the right atom and
matrix by Spectroscopy
1. Absorption
2. Emission/ Fluorescence
3. Lifetime of energy levels

10. A 2 kW CO2 Laser

11. Laser History - continued
60-ties laser invented and most effects discovered
70-ties a solution looking for a problem ...
80-ties problems discovered!
90-ties commercial success!!
00-ties everybodies toy!!!
Diode Pumped Solid-state lasers (DPSSL)
Fiber lasers
Diode lasers

12. The diode laser The diode laser and the optical
the smallest and most frequently used laser
The diode laser and the optical
fiber is the backbone of
telecommunication
Nobel prize 2000 Zhores I. Alferov A.F. Ioffe Physico-Technical Institute, St. Petersburg

13. Types of diode lasers Edge emitters Array lasers Broad area diodes
Tapered diodes

14. Types of diode lasers -continued
VECSELs – OPSL
A vertical-external-cavity surface-emitting-laser (VECSEL)
is a small semiconductor laser similar to a
vertical-cavity surface-emitting laser (VCSEL).

15. Solving the spectral problem
Grating stabilization – feed-back
Fiber Bragg Gratings
Diffraction gratings
Volume Bragg Gratings
Integrated gratings

16. Tuning the diode – alternative feed-back techniques
Stretching the FBG
Temperature tune or translating a chirped VBG
Retroreflector
= continuous tuning

17. Diode laser tuning with strechable silicone grating
Moulded silicone grating
Littrow configuration
O2 sensing in air
Laser tunable
over 3 nm
S Bertani, B Jacobsson, F Laurell, V Pasiskevicius and M Stjernström, Opt. Express, 14, 11982, 2006.

18. Increasing the Power- Resonant Cavities
Resonant cavities require
advanced locking techniques
W. Risk, Compact Blue-Green Lasers

19. The Diode-Pumped Solid-State Laser
Converts a poor diode laser beam to a high quality solid-state laser beam
- spatially, spectrally and temporally engineered
Solid-
State
Material
Functional
element
Diode
Pump
Allows functionality to be integrated in the laser

20. DPSSL scales to high power
heat
laser
pump
Minimize the quantum
defect – i.e. heat