ULTRA-PRECISE PHASE CONTROL OF SHORT PULSES – APPLICATIONS TO NONLINEAR SPECTROSCOPY

Abstract

Precise phase control of femtosecond lasers has become increasingly important as novel applications utilizing the femtosecond laser-based optical comb are developed that require greater levels of precision and higher degrees of control [1]. Improved stability is beneficial for both “frequency domain” applications, where the relative phase or “chirp” between comb components is unimportant (e.g. optical frequency metrology), and, perhaps more importantly, “time domain” applications where the pulse shape and/or duration is vital, such as in nonlinear optical interactions [2]. For both types of applications, minimizing jitter in the pulse train and noise in the carrier-envelope phase is often critical to achieve the desired level of precision. Phase-stabilized mode-locked femtosecond lasers have played a key role in recent advances in optical frequency measurement [3,4], carrier-envelope phase stabilization [2,5,6], alloptical atomic clocks [7,8], optical frequency synthesizers [9], coherent pulse synthesis [10], and ultra-broad, phase coherent spectral generation [11]. The capability of absolute optical frequency measurements in the visible and IR spectral regions adds a new meaning to the term of precision molecular spectroscopy. Understanding of molecular structure and dynamics often involves detailed spectral analysis over a broad wavelength range. Such a task can now be accomplished with a desired level of accuracy uniformly across all relevant spectral windows, allowing precise investigations of minute changes in the molecular structure over a large dynamic range. For example, absolute frequency measurement of vibration overtone transitions and other related