Electric field filamentation and higher harmonic generation in very high frequency capacitive discharges

Static-electric-field effects on high harmonic generation.

Direct observation of laser filamentation in high-order harmonic generation.

We investigate the spatial evolution of a laser pulse used to generate high-order harmonics (orders ranging from 45 to 91) in a semi-infinite helium-filled gas cell. The 5 mJ, 30 fs laser pulses experience elongated focusing with two distinct waists when focused with f/125 optics in 80 Torr of helium. Extended phase matching for the generation of harmonics occurs in the region between the doubl...

Time Frequency Analysis of Higher Harmonic Generation in a Three Color Laser Pulse

high harmonic generation is a useful tool for the generation of short, intense attosecond pulses. In order to simulate high harmonic generation, we performed a numerical solution to the time dependent Schrödinger equation. by considering dipole approximation, we predicted generation of a 53 attosecond pulse. In order to see the time and frequency of emission of attosecond pulse, we exploit...

Anomalous capacitive sheath with deep radio-frequency electric-field penetration.

A novel nonlinear effect of anomalously deep penetration of an external radio-frequency electric field into a plasma is described. A self-consistent kinetic treatment reveals a transition region between the sheath and the plasma. Because of the electron velocity modulation in the sheath, bunches in the energetic electron density are formed in the transition region adjacent to the sheath. The wi...

Electric-field-induced second-harmonic generation in GaN devices.

Electric-field-induced second-harmonic generation is used to detect electric fields in a GaN UV Schottky photodiode and in a GaN light-emitting diode. The second-harmonic signal is measured as a function of bias voltage and incident laser power. This technique is sensitive to small applied voltages and can be used to track electronic waveforms. The photocurrent generated by this technique is fo...