Few-cycle, carrier–envelope-phase-stable laser pulses from a compact supercontinuum source

Abstract

We report on a few-cycle, carrier–envelope-phase-stable laser source based on supercontinuum generation driven by an amplified Er:fiber-based system. Laser pulses from an Er:fiber oscillator are amplified, and these amplified pulses generate a stable supercontinuum in a highly nonlinear optical fiber. The short- and long-wavelength tails of this continuum are used in an 𝑓-to-2𝑓 interferometer to stabilize the carrier–envelope phase (CEP) of the Er:fiber oscillator via an acousto-optic modulator. Compressing the central part of the continuum, we generate a train of CEP-stabilized laser pulses with a central wavelength of 1170 nm, duration of 9.1 fs (∼2.3 optical cycles), and repetition rate of 78.4 MHz. Characterizing the CEP stability of our output pulse train with an out-of-loop 𝑓-to-2𝑓 interferometer, we find a phase jitter of only 157.4 mrad when integrating the radiofrequency spectrum from 5 mHz to 5 MHz.