Frequency-selective Q-switched repetitively pulsed slab RF-discharge carbon monoxide laser

•Frequency selective single- and multi-line Q-switched slab RF discharge CO laser.•Frequency selective schemes with diffraction grating or spectral filters for CO laser.•Long-wave part of CO laser spectrum for further conversion into the long-wave mid-IR. Q-switched cryogenically cooled slab RF discharge CO laser operating in multi-line mode, single-line mode with a diffraction grating, and also with frequency selection by special spectral filters situated both outside and inside the laser cavity was experimentally studied. Characteristics of CO lasing on individual ro-vibrational spectral lines produced by this laser with various cavities under the same active medium and pump parameters were compared. Application of output couplers with a relatively narrow spectral band of high transmittance compared to the non-selective CO laser range of operation, but with high reflection in the rest of the range, was effective for obtaining narrow-band multiline lasing. For selection of the long-wave part of Q-switched CO laser spectrum, which was needed for frequency conversion into the long-wave mid-IR when mixing with CO2 laser emission, application of a broadband spectral filter with a very low reflection coefficient in the spectral range where lasing was necessary to be suppressed (sort of a step function) proved to be efficient being installed outside the laser cavity.