1. Dye Lasers Rob van Rooij Images from:
Laser Fundamentals 2nd edition, William T. Silfvast

2. Types of Dye-lasers Dye-lasers come in various types:
Laser-pumped pulsed tuneable dye-lasers
Flashlamp-pumped pulsed dye-lasers
Mode-locked dye lasers
Continuous-wave (cw) tuneable dye-lasers

3. CW-pumped dye-laser Argon ion laser used as pumping source
Dyes have broad fluorescent linewidths:
50 – 100 nm
Using various dyes, it is possible to:
Continuously tune the laser over the entire visible spectrum

4. Structure Dyes are complex molecules Simplified energy-level diagram 
i.e., rhodamine B: C28H31Cl N2O3
Simplified energy-level diagram 
4 level system

5. Structure Between S or T states: Vibrational levels:
Rotational levels:
~ 10-3 eV (finestructure)
Broad absorption and emission curves

6. Structure Rotational and vibrational decay in S1: 10-12 – 10-13 s
Emission S1  S0:
10-9 s
T1  S0: 10-4 – 10-5 s

7. Absorption & Emission

8. Triplet-Triplet Absorption

9. Triplet quenching Triplet quenching-agent to promote
T1  S0 transitions
In CW dye-lasers, rapid flow of the dye solution to physically remove triplet state population

10. Characteristics Small-signal gain coefficient g0 = 500/m
Stimulated emission cross-section ul= 1 to 4 x m2
Upper laser level lifetime u = 2 to 5 x 10-9 s
Saturation intensity: 109 to 1010 W/m ( )
Power density to reach threshold: ~100 kW/cm2
Pumping power: several Watts
Output power: up to 2 W
Transmission output mirror: 10 to 20 percent

11. Setup

12. Birefringent tuning element
Birefringent materials split light into two rays, at a different refractive index
Rotation of the filter tunes the cavity to 1/1000th of a nm

13. Dye-laser in action