Design of a transversely pumped, high repetition rate, narrow bandwidth dye laser with high wavelength stability

Abstract

The paper presents the design and performance of a transversely pumped, narrow bandwidth, high wavelength stability tunable dye laser that neither uses low expansion coefficient materials for construction nor incorporates any active control on the wavelength or the dye solution and environmental temperature as generally used in such lasers. The scheme essentially involves designing the mechanical assembly in such a way that, when bolted together it forms a massive monoblock, enclosing all the optical components and the dye laser axis within itself. This ensures the environmental temperature changes can only affect the output characteristics over long time scale. Short term (pulse to pulse) fluctuations in wavelengths and bandwidths, generally associated with the dye flow instabilities, were minimized by using a specially designed a dye cell made of a near 360°-curved rectangular duct, in which the turbulent flow is transformed itself into laminar flow as it reaches the dye laser axis. The laser was operated with Rhodamine 6G-ethanol-ethylene glycol solution, pumped by a copper vapor laser operating at 5.6 kHz. The dye laser output, consisting of three axial modes, separated by about 990 MHz, was stable over the observation period of about 90 min. Maximum long term (>1 h) fluctuation in Δν/ν was about ±3.6×10−6. The bandwidth of the individual mode varied between 245 MHz to 315 MHz.