Visible-spanning flat supercontinuum for astronomical applications

TL;DR

This paper presents a novel, broad, flat visible supercontinuum generated by a dispersion-engineered photonic crystal fiber pumped by a high-repetition-rate Ti:sapphire laser, suitable for astrophysical spectrograph calibration.

Contribution

The work demonstrates a simple, efficient method to produce a flat visible supercontinuum spectrum using a specialized fiber and laser system, advancing astronomical calibration tools.

Findings

Achieved a flat spectrum within 3 dB over 490-690 nm

Generated a supercontinuum with a blue tail below 450 nm

System is suitable for precise astrophysical spectrograph calibration

Abstract

We demonstrate a broad, flat, visible supercontinuum spectrum that is generated by a dispersion-engineered tapered photonic crystal fiber pumped by a 1 GHz repetition rate turn-key Ti:sapphire laser outputting $\sim$ 30 fs pulses at 800 nm. At a pulse energy of 100 pJ, we obtain an output spectrum that is flat to within 3 dB over the range 490-690 nm with a blue tail extending below 450 nm. The mode-locked laser combined with the photonic crystal fiber forms a simple visible frequency comb system that is extremely well-suited to the precise calibration of astrophysical spectrographs, among other applications.