Spectrally resolved optical frequency comb from a self-referenced 5 GHz femtosecond laser

TL;DR

This paper presents a 5GHz repetition rate femtosecond laser with spectral broadening and self-referencing, enabling high-resolution mode resolution and potential applications in spectroscopy and waveform synthesis.

Contribution

The development of a high-power, self-referenced 5GHz femtosecond laser with spectrally resolved comb modes using a VIPA spectrometer is novel.

Findings

Achieved octave-spanning spectrum through spectral broadening.

Resolved individual comb modes at 5GHz with high-resolution spectrometer.

Demonstrated isolation of single comb elements at microwatt power levels.

Abstract

We report a mode-locked Ti:sapphire femtosecond laser with 5GHz repetition rate. Spectral broadening of the 24 fs pulses in a microstructured fiber yields an octave-spanning spectrum and permits self-referencing and active stabilization of the emitted femtosecond laser frequency comb (FLFC). The individual modes of the 5GHz FLFC are resolved with a high-resolution spectrometer based on a virtually imaged phased array (VIPA) spectral disperser. Isolation of single comb elements at a microwatt average power level is demonstrated. The combination of the high-power, frequency-stabilized 5GHz laser and the straightforward resolution of its many modes will benefit applications in direct frequency comb spectroscopy. Additionally, such a stabilized FLFC should serve as a useful tool for direct mode-by-mode Fourier synthesis of arbitrary optical waveforms.