Effect of optical turbulence in the dye medium on the bandwidth of a narrowband, high-repetition-rate dye laser

Abstract

An analysis of turbulence in the dye medium of a high-repetition-rate narrowband dye laser is presented, and it is shown that the output bandwidth is proportional to the turbulence length scale, which depends on the Reynolds number. The length scale and the bandwidth both first decrease and then increase as the Reynolds number is increased from -200 to -20,000. The observed bandwidth, as we report and as in the published literature, confirms the validity of the analysis. A Rhodamine 6G grazing-incidence grating, stable dye laser transversely pumped by a copper-vapor laser was used in the experiments.

The effect of varying the hydraulic parameters of a flow cell in a dye laser pumped by a copper vapor laser

“…It is worth noting here that the curve (b) of Fig. 6(b) for 0.5 mm gap (aspect ratio G(1801)=50 and curvature ratio b(1801)=81) is merely the extension of the numerically obtained eddy sizes reported earlier [16], which is etc. may come into play.…”

“…For higher Reynolds number, the wavelength variations from Eq. (16) for known values of temperature variation at different Reynolds numbers plotted in Fig. 7 may be anticipated.…”

“…Pressure drop, wall roughness, turbulence, eddies, and cavitations are detrimental for maximizing the flow rate. We have reported earlier on the mechanism of eddy generation in the flow field and its influence on dye laser output characteristics [16,17]. In this paper, we report our numerical and experimental observations on the flow field behavior in a similar dye cell (henceforth referred to as test flow cell) by changing the flow gap, aspect ratio, and radius of curvature for the first time (Fig.…”

“…The expansion of functions D k and D e and the values of constants C 1 , C 2 were reported in detail earlier [16,17].…”

“…They also reported a dye laser with an 8 mm gain length at flow velocities 0.6-8 m/s and observed frequency jitter due to turbulence at high flow rates [14]. In a transversely pumped dye laser, the pump beam is mostly absorbed in the boundary layer of the flow and the dye laser axis lies in the boundary layer region [11,16,17]. Since the pump light excites a thin layer near a wall of the dye cell, diffraction causes substantial angular spread of the emerging light, which would severely limit the resolution obtainable [18].…”