Making Small Holes With Lasers.

The femtosecond laser is an advantageous tool for manipulating matter on small scales as it can precisely remove material with minimal collateral effects. The nonlinear mechanisms mediating this damage allow for laser ablation to be confined to tens of nanometers in width. Results presented here expand upon the physics of this type of damage. A number of new damage phenomena for tightly focused femtosecond laser damage in glass are presented and physical mechanisms for their generation are suggested. The first novel phenomenon is the formation of blister-like structures leading to the ejection of thin, flat rings surrounding central damage regions, termed “grommets”. A study of damage depth from single pulse damage is also presented using a number of different measurement techniques including sample cleavage, focused ion beam cross sectioning, and acetate film imprinting. These techniques reveal damage extending far deeper into the target than was expected from the intensity distribution of the focusing optics. Experiments presented here show that a likely source for this elongation of damage is microscale self-focusing. Finally, a range of applications is presented, demonstrating the versatility and speed of single pulse nanochannel fabrication.PhDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/78855/1/jfherbst_1.pd