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Ultrafast Laser-Induced Damage And The Influence Of Spectral Effects, Jeremy Gulley
Ultrafast Laser-Induced Damage And The Influence Of Spectral Effects, Jeremy Gulley
Jeremy R. Gulley
Numerous studies have investigated the prerequisite role of photoionization in ultrafast laser-induced damage (LID) of bulk dielectrics. This study examines the role of spectral width and instantaneous laser frequency in LID using a frequency dependent multiphoton ionization (MPI) model and numerical simulation of initially 800 nm laser pulses propagating through fused silica. Assuming a band gap of 9 eV, MPI by an 800 nm field is a six-photon process, but when the instantaneous wavelength is greater than 827 nm an additional photon is required for photoionization, reducing the probability of the event by many orders of magnitude. Simulation results suggest …
Modeling Free-Carrier Absorption And Avalanching By Ultrashort Laser Pulses, Jeremy Gulley
Modeling Free-Carrier Absorption And Avalanching By Ultrashort Laser Pulses, Jeremy Gulley
Jeremy R. Gulley
In the past decade it was demonstrated experimentally that negatively-chirped laser pulses can lower the surface LIDT for wide band-gap materials by decreasing the number of photons required for photoionization on the leading edge of the pulse. Similarly, simulations have shown that positively-chirped pulses resulting from selffocusing and self-phase modulation in bulk dielectrics can alter the onset of laser-induced material modifications by increasing the number of photons required for photoionization on the leading edge of the pulse. However, the role of multi-chromatic effects in free-carrier absorption and avalanching has yet to be addressed. In this work a frequency-selective model of …
Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley
Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley
Jeremy R. Gulley
Numerous studies have investigated the role of photoionization in ultrafast laser-induced damage of bulk dielectrics. This study examines the role of spectral width and instantaneous laser frequency in laser-induced damage using a frequency dependent multiphoton ionization model and numerical simulation of an 800 nm laser pulse propagating through fused silica. When the individual photon wavelengths are greater than 827 nm, an additional photon is required for photoionization, reducing the probability of the event by many orders of magnitude. Simulation results suggest that this frequency dependence may significantly affect the processes of laser-induced damage and filamentation.