Abstract
Ultrafast optical field waveform generation and measurement (lightwave electronics) affords a capability to attain microscopic control of electronic motion in the attosecond time scale, so it becomes an emerging science and technology of significant impact. The dynamics of electrons in atomic scale is of fundamental physical importance. Investigation of microscopic electronic processes and control of the physical processes enabled by electron dynamics will benefit substantially by having the ability to synthesize and shape electromagnetic field waveforms in the attosecond time scale. The optical field waveform synthesizer, or optical function generator which is a type of function generator in the optical regime, could become a basic and important scientific tool and would have broad impact in many research areas. It is therefore scientifically prudent to develop techniques to synthesize single cycle optical fields (waveforms) of arbitrary shape in the femtosecond to attosecond time frame. In this dissertation, we describe how we have experimentally synthesized periodic electric field waveforms of various shapes in the femtosecond to subfemtosecond time scale. In order to synthesize periodic pulses whose carrier-envelope phase (CEP) is controllable, we took a nanosecond pulse at a fundamental frequency and generated its second harmonic. We then used the two pulses to drive the vibrational coherence of the hydrogen molecule and produced by molecular modulation a multi-octave spanning harmonic frequency comb that is fully carrier-envelope phase controllable. We employed f-2f interferometry to measure the heterodyne signals and determined the relative phase among the comb components (harmonics), which verified phase-locking among the harmonics and stabilization of the CEP among the pulses from shot-to-shot. We then used the first five harmonics of the comb to synthesize various non-sinusoidal optical field waveforms with the help of a liquid crystal spatial light modulator. These waveforms were verified using shaper-assisted linear cross-correlation, a technique based on pulse-shaping that allows visualization of these phase-stable waveforms. We have also developed an optical field waveform synthesizer consisting of a nonlinear photonic crystal and an acousto-optical modulator. This system is more compact and convenient because all of the essential components are solid-state. Hence we have developed two types of optical function generators which are the prototype of a new tool that will provide femtosecond to subfemtosecond periodic electric field waveforms of arbitrary shape for the research community in fields such as nanoelectronics, nanomaterial, ultrafast electronics, and chemical reaction control.