A computational model for transient temperature rise in a dye laser gain medium pumped by a copper vapor laser

Abstract

Spectrally stable dye lasers play an important role in techniques based on high resolution spectroscopy and atomic spectroscopy. The spectral purity of a dye laser is affected when the pump power to it is increased beyond the threshold. When the pump power is increased beyond the threshold, two mode oscillations occur which decrease the spectral purity of the dye laser. The effect of higher pump pulse energies on transient thermal effects has been studied using a computational fluid dynamics (CFD) model and the disturbances to the laser cavity have been studied using commercially available ray tracing software. The change in the cavity length was determined from the CFD model for several dye concentrations and pump powers. The results of the CFD model have been verified by published results and experimental results from our system. Our study shows that in the longitudinally pumped single mode laser change in the cavity length is a more dominant disturbance than thermal blooming. Our model is useful for the design of the dye cell.

Characterization of dye cells for a high-repetition-rate pulsed dye laser by particle image velocimetry (PIV)

“…The dye flow channel should reduce thermal and pressure variations in the flowing dye solution, particularly near the active volume. It has been reported that the higher flow velocity in the dye cell results in self-heating due to wall friction [7]. A thoughtful design of the dye cell flow channel, and suitable selection of active volume and pump power levels, will help to resolve these problems for operation of the dye laser at high repetition rate [16].…”

“…To study the several flow-related parameters for a dye laser beam of reasonably good quality, we have developed a computational model to avoid extensive, time-consuming experimental studies for obtaining a suitable dye flow channel. We have computationally evaluated the designs of flow channel for a dye cell that are suitable for a pulsed dye laser in a general-purpose computational fluid dynamics (CFD) code and the details of the CFD model have been reported earlier [7,16,27]. In CFD the equations governing the flow and their interaction between fluid and flow channel have been solved numerically.…”

“…A high pump power in the dye cell degrades the optical quality of the dye laser beam due to thermo-optical effects. It has been reported that the beam divergence as well as beam propagation param eters were affected by high pump powers in the dye lasers [7,29]. A high flow velocity in the dye cell removes the heated volume and also extracts photodegraded products from the active region [30][31][32].…”

“…The spectral width of the dye laser is determined by high-frequency fluctuations around a mean frequency as well as slow frequency drift of the mean wavelength [6]. The slow drifts in the frequency are generally initiated by heating of the laser gain medium due to frictional heat (solvent friction with the walls of the dye cell due to viscosity), environ mental temperature (dye solvent temperature) and average pump power to the dye laser (due to non-radiative transitions) [7].…”

Effect of Flow Induced Parameters on the Output of A High Repetition Rate Dye Laser

“…While the influence of velocity fluctuation and dye solution temperature fluctuation on fluctuation in the optical path within laser resonator is reported in the literature [8,9,10], the effect of flow induced vibration on mechanical instabilities of dye laser setup is not yet reported in detail. An unperturbed optical layout provides good frequency stability, but there are some practical limitations.…”