Single mode operation of a narrow bandwidth dye laser using a single prism, grazing incidence grating long cavity

The single mode pulsed dye laser is an attractive tool for many spectroscopic applications. Long cavity tunable dye lasers generally operate in multi-longitudinal modes within the bandwidth of gain profile. Single longitudinal mode oscillation can be obtained by either making the cavity short enough or introducing an additional loss mechanism, in which all modes but one have a gain less than their loss. A new technique to achieve single mode operation in a long cavity dye laser, based on Rhodamine 6G dye in ethanol and ethylene glycol solution, pumped by a high repetition rate copper vapor laser, is reported. This laser, which operates in three modes in grazing incidence grating configuration (cavity length of 16 cm), has been made to lase in single mode by increasing the loss in the resonator through beam walk-off.