Laser pulsetrain pulse-picker for subharmonic frequencies

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We request support to buy accessories for an existing research-laser system, for which physics research is generally funded by NSERC Discovery grant and photonics research by funding for special applications from CIPI, as well as biophysics research by Ontario Centres of Excellence.  Three professors and five graduate students work will be enhanced by this grant.   The existing laser-system is complete and functional;  this equipment will permit us to access new regimes in the way in which laser pulses are delivered when doing ultrafast laser-materials interaction for optics, materials-processing, or biotissue interaction relevant to advanced and developmental laser surgery.  We have a recent patent in this area, but progress has been resource-limited, and we have given up some ground to groups like that of Mazur at Harvard.   The Equipment:  a pulse-picker selection system, to be efficiently shared between two different lasers, that will let us configure our 100MHz laser pulsetrain to deliver instead 50 MHz, 25 MHz, 12 MHz, or various combinations of pulses for delivery to different materials or biotissues.   The Science:  Femtosecond lasers are known to deposit laser energy into electrons on a timescale short compared to the subsequent thermalization to the lattice.  High repetition-rate lasers (> 1 MHz) deposit the next pulse of energy to electrons before this lattice-energy has fully dissipated, and the material relaxed thermally.  By the paradigm of controlling fluence delivery across these two time-scale regimes, we believe we can make non-equilibrium manipulations of the state of glasses and other optical materials, and do this at a nanometer-scale.  Essentially, we want to control, at any time, the partition of energy between electrons and phonons in the material - approximately, to influence the chemical impact and the thermal/mechanical impact in the material separately.  We've shown this gives us access to new materials science, and new ways of microprocessing different glasses, ceramics and other brittle materials.