Ultrasensitive spectroscopy, the ultrastable lasers, the ultrafast lasers, and the seriously nonlinear fiber: A new alliance for physics and metrology

Abstract—We now appreciate the fruit of decades of develop-ment in the independent fields of ultrasensitive spectroscopy, ultra-stable lasers, ultrafast lasers, and nonlinear optics. But a new fea-ture of the past two or three years is the explosion of interconnect-edness between these fields, opening remarkable and unexpected progress in each, due to advances in the other fields. For brevity, we here focus mainly on the new possibilities in the field of optical frequency measurement. Index Terms—Femtosecond lasers, frequency control, frequency synthesizers, measurement, optical frequency comb, optical fre-quency measurement, stabilized laser. I. INTRODUCTION AND OVERVIEW SYSTEMATIC work in standards labs worldwide, overthirty years, has shown reliable progress in the art of stable lasers and measurement of their frequencies. By now, lasers are controlled in the domain usin