Continuous-wave organic dye lasers and methods
An organic dye laser produces a continuous-wave (cw) output without any moving parts (e.g., without using flowing dye streams or spinning discs of solid-state dye media to prevent photobleaching) and with a pump beam that is stationary with respect to the organic dye medium. The laser's resonant cavity, organic dye medium, and pump beam are configured to excite a lasing transition over a time scale longer than the associated decay lifetimes in the organic dye medium without photobleaching the organic dye medium. Because the organic dye medium does not photobleach when operating in this manner, it may be pumped continuously so as to emit a cw output beam. In some examples, operation in this manner lowers the lasing threshold (e.g., to only a few Watts per square centimeter), thereby facilitating electrical pumping for cw operation.
1. An organic dye laser comprising:
a resonant cavity;
an organic dye medium disposed with respect to the resonant cavity such that, during operation of the organic dye laser, the organic dye medium is electromagnetically coupled to the resonant cavity; and
an optical pump source disposed with respect to the resonant cavity and the organic dye medium such that, during operation of the organic dye laser, the optical pump source excites the organic dye medium with a continuous-wave pump beam that is stationary with respect to the organic dye medium on a macroscopic scale so as to stimulate emission of a continuous-wave beam, from the organic dye medium, that resonates within the resonant cavity.
2. The laser of claim 1 , wherein the resonant cavity is characterized by a total quality factor Q tot of about 5×10 3 to about 5×10 6 .
3. The laser of claim 1 , wherein the resonant cavity is characterized by a spontaneous emission enhancement factor F p of about 1 to about 100.
4. The laser of claim 1 , wherein the organic dye medium comprises a liquid.
5. The laser of claim 1 , wherein the organic dye medium comprises a solid.
6. The laser of claim 1 , wherein the organic dye medium has a dye concentration of about 0.1 mM to about 10 mM.
7. The laser of claim 1 , wherein the organic dye medium is characterized by a lasing mode confinement factor Γ s >0.1.
8. The laser of claim 1 , wherein the organic dye medium comprises:
at least one quenching molecule to quench at least one undesired transition caused by absorption of the continuous-wave pump beam by the organic dye medium.
9. The laser of claim 1 , wherein the optical pump source comprises a tunable optical pump source.
10. The laser of claim 1 , further comprising:
an actuator, coupled to the resonant cavity, to vary a length of the resonant cavity.
11. A method of generating a continuous-wave output beam from an organic dye medium electromagnetically coupled to a resonant cavity, the method comprising:
(A) generating a continuous-wave pump beam that is stationary with respect to the organic dye medium on a macroscopic scale; and
(B) pumping the organic dye medium with the continuous-wave pump beam so as to cause the organic dye medium to emit a continuous-wave output beam.
12. The method of claim 11 , wherein (A) comprises:
tuning a wavelength of the continuous-wave pump beam so as to vary an amplitude of the continuous-wave output beam.
13. The method of claim 11 , further comprising:
(C) disposing at least one quenching molecule in electromagnetic communication with the organic dye medium so as to quench at least one undesired transition caused by pumping the organic dye medium with the continuous-wave pump beam.
14. The method of claim 11 , further comprising:
(D) varying a length of the resonant cavity so as to vary a wavelength of the continuous-wave output beam.
15. A laser comprising:
a resonant cavity characterized by a spontaneous emission coupling factor β and a spontaneous emission enhancement factor F p ;
an organic gain medium characterized by a population N tot and a confinement factor Γ s ; and
a pump source to excite a transition of the organic gain medium characterized by a total emission lifetime τ spont , a triplet decay lifetime τ t , and an intersystem crossing lifetime τ isc so as to produce at least one photon having a loss rate of 1/τ′ loss due to both loss in the resonant cavity and absorption in the organic gain medium, wherein:
β
F
p
Γ
s
N
tot
τ
spont
>
(
1
+
τ
t
/
τ
tsc
)
τ
loss
″
.
16. The laser of claim 15 , wherein the spontaneous emission enhancement factor F p is greater than 1.
17. The laser of claim 15 , wherein the organic gain medium comprises a solid.
18. The laser of claim 15 , wherein the organic gain medium comprises a liquid.
19. The laser of claim 15 , wherein the total emission lifetime τ spont is about 0.1 ns to about 10 ns.
20. The laser of claim 15 , wherein the triplet decay lifetime τ t is about 100 ns to about 10 ms.
21. The laser of claim 15 , wherein the intersystem crossing lifetime τ isc is about 10 ns to about 1 ms.
22. The laser of claim 15 , wherein the loss rate of 1/τ′ loss is about 5×10 8 s −1 to about 5×10 13 s −1 .