In this work we report on the optimization of the conversion efficiency of the harmonic generation process, by adaptive control of the wavefront of sub-10-fs light pulses, obtained by using a deformable mirror and a genetic algorithm. Sub-10-fs, 0.2-mJ energy light pulses, generated by the hollow-fiber compression technique, were focused in the gas target (argon or neon) by a 250-mm focal-length mirror. Pulse wavefront correction has been achieved by using a deformable mirror (DM) controlled by 37 actuators distributed on a honeycomb pattern of 15 mm diameter. The harmonic radiation was observed by a soft-X-ray spectrometer, with double output: time-integrated high-resolution bidimensional focal-plane image and real-time (I kHz) intensity of a suitable spectral region. This latter signal was used as fitness parameter for the genetic algorithm; an initial population of DM configurations was initialized with random values of the actuator signals. A new generation of DM configurations is derived from ordering, selection and transformation of previous generation, up to the convergence to the fittest individual.
Adaptive wavefront control based on genetic algorithm for the enhancement of high-order harmonic generation driven by two-cycle laser pulses
Bonora S;Poletto L;Sansone G;Stagira S;Vozzi C;Nisoli M;De Silvestri S
2004
Abstract
In this work we report on the optimization of the conversion efficiency of the harmonic generation process, by adaptive control of the wavefront of sub-10-fs light pulses, obtained by using a deformable mirror and a genetic algorithm. Sub-10-fs, 0.2-mJ energy light pulses, generated by the hollow-fiber compression technique, were focused in the gas target (argon or neon) by a 250-mm focal-length mirror. Pulse wavefront correction has been achieved by using a deformable mirror (DM) controlled by 37 actuators distributed on a honeycomb pattern of 15 mm diameter. The harmonic radiation was observed by a soft-X-ray spectrometer, with double output: time-integrated high-resolution bidimensional focal-plane image and real-time (I kHz) intensity of a suitable spectral region. This latter signal was used as fitness parameter for the genetic algorithm; an initial population of DM configurations was initialized with random values of the actuator signals. A new generation of DM configurations is derived from ordering, selection and transformation of previous generation, up to the convergence to the fittest individual.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
