Studies on 20 kHz pulse repetition rate class narrow line-width dye laser

This paper presents a first comprehensive study on 20 kHz pulse repetition rate (PRR) class dye laser with an emphasis to bring out the role of dye solution flow rate on the laser power, line-width, wavelength stability and pulse characteristics of a narrow line-width dye laser. The study was performed for Rh6G–ethanol dye solution for flow rates from 2 to 12 lpm. The dye laser based on glass dye cell and the pump source was copper hydrogen bromide (Cu–HBr) laser at a fixed average power of 8 W and repetition rate of 18 kHz. The dye laser resonator was grazing incidence grating (GIG) cavity with double prism beam expander. A high precision wavelength-meter was used to record the online variation in dye laser line-width and wavelength. It is established that the dye solution flow rate significantly affected the dye laser performance. The best dye laser spectral purity was obtained at 3–4 lpm flow rate regime. The line-width and wavelength stability worsened both below and above the flow rates of 3–4 lpm. The best dye laser output power was obtained at 9 lpm flow rate and it decreased only slightly as flow rate is increased to 12 lpm. The dye solution flow rate also affected the dye laser pulse shape and width.