Laser

A method of pumping a laser gain medium comprising directing pulses of laser light sequentially to a series of separate locations arranged longitudinally along the gain medium in the direction of laser propagation, using each pulse to pump a different portion of the gain medium to cause a localised population inversion, and timing the sequence of pulses to pump the gain medium, wherein the upper state lifetime of the gain medium is less than the light crossing time of the gain medium.

A laser device in which a series of optical delay lines are arranged to transmit pulses from a pump laser to a series of separate locations arranged along a solid gain medium in the direction of laser propagation in the gain medium, each optical delay line being arranged to pump a different portion of the gain medium to cause a localised population inversion, and the pulse transmission delays provided by the optical delay lines are selected to deliver a sequence of pulses to the portions of the gain medium such that each portion will in turn contribute to amplification of a laser propagating within the gain medium, in which the gain medium is located in a resonant cavity provided with end mirrors whereby the laser pulse will be reflected between the end mirrors to make multiple passes through the gain medium.

A laser device in which a series of optical delay lines are arranged to transmit pulses from a pump laser to a series of separate locations arranged along a solid gain medium in the direction of laser propagation in the gain medium, each optical delay line being arranged to pump a different portion of the gain medium to cause a localised population inversion, and the pulse transmission delays provided by the optical delay lines are selected to deliver a sequence of pulses to the portions of the gain medium such that each portion will in turn contribute to amplification of a laser propagating within the gain medium, in which the series of optical delay lines split into at least one further series such that each optical delay line in the further series will deliver its pulse to a location that is laterally displaced from the locations associated with the other series of optical delay lines.

A laser device in which a series of optical delay lines are arranged to transmit pulses from a pump laser to a series of separate locations arranged along a solid gain medium in the direction of laser propagation in the gain medium, each optical delay line being arranged to pump a different portion of the gain medium to cause a localised population inversion, and the pulse transmission delays provided by the optical delay lines are selected to deliver a sequence of pulses to the portions of the gain medium such that each portion will in turn contribute to amplification of a laser propagating within the gain medium, in which the gain medium is defined by at least two types of gain medium arranged end-to-end.