A gain-switched laser with pump system, wherein said laser is configured to generate laser pulses on demand at arbitrary repetition frequency, said generated pulses having constant duration and peak power, wherein the said laser comprises: - a first active element installed between two reflective elements (3a,3b), thereby forming an oscillator for generating laser pulses, - a pump system having an output, which is coupled or spliced to a first side of the oscillator and is configured to pump the oscillator and an amplifier, wherein the pump system comprises control electronics, a primary and a secondary pump module and a beam combiner, said primary and secondary pump module each comprises at least one pump laser diode, and wherein the primary pump module is arranged to generate short pump pulses with a duration up to 10 μs, and the output power of the secondary pump module is arranged to be continuous or modulated depending on the required control of the laser pulse parameters, and in either case the primary and the secondary module are arranged to operate at different peak powers, said secondary module being arranged to operate at lower peak power than the primary module wherein the power generated by the secondary module is configured to ensure constant population inversion level of the laser oscillator active medium between laser pulses so as to decrease the effect of active medium relaxation caused by spontaneous emission between laser pulses, and - on a second side of the oscillator a second active element, which serves as the amplifier, is configured for absorbing residual pump light transmitted through the oscillator. - a first active element installed between two reflective elements (3a,3b), thereby forming an oscillator for generating laser pulses, - a pump system having an output, which is coupled or spliced to a first side of the oscillator and is configured to pump the oscillator and an amplifier, wherein the pump system comprises control electronics, a primary and a secondary pump module and a beam combiner, said primary and secondary pump module each comprises at least one pump laser diode, and wherein the primary pump module is arranged to generate short pump pulses with a duration up to 10 μs, and the output power of the secondary pump module is arranged to be continuous or modulated depending on the required control of the laser pulse parameters, and in either case the primary and the secondary module are arranged to operate at different peak powers, said secondary module being arranged to operate at lower peak power than the primary module wherein the power generated by the secondary module is configured to ensure constant population inversion level of the laser oscillator active medium between laser pulses so as to decrease the effect of active medium relaxation caused by spontaneous emission between laser pulses, and wherein the pump system comprises control electronics, a primary and a secondary pump module and a beam combiner, said primary and secondary pump module each comprises at least one pump laser diode, and wherein the primary pump module is arranged to generate short pump pulses with a duration up to 10 μs, and the output power of the secondary pump module is arranged to be continuous or modulated depending on the required control of the laser pulse parameters, and in either case the primary and the secondary module are arranged to operate at different peak powers, said secondary module being arranged to operate at lower peak power than the primary module wherein the power generated by the secondary module is configured to ensure constant population inversion level of the laser oscillator active medium between laser pulses so as to decrease the effect of active medium relaxation caused by spontaneous emission between laser pulses, and - on a second side of the oscillator a second active element, which serves as the amplifier, is configured for absorbing residual pump light transmitted through the oscillator.