Carbide spectral broadening and harmonic generation

Characterizing harmonics from a spectrally broadened Yb Carbide laser using using self-diffraction frequency-resolved optical gating (SD-FROG).

We characterize second and fourth harmonics generated by the native output from a Yb Carbide laser, and then characterize the second and fourth harmonics using the spectrally broadened and post-compressed Carbide output. We make use of self-diffraction frequency-resolved optical gating (SD-FROG) to perform pulse characterization of the harmonics, while second harmonic generation frequency-resolved optical gating (SHG-FROG) is used to characterize the fundamental.

Below is a schematic depicting different harmonic generation schemes using bulk crystals.

A schematic depicting different harmonic generation schemes using BBO crystals.

The laser set-up is depicted below, showing the stretched ~2m long hollow capillary fiber and the chirped mirrors used for post-compression.

The Carbide laser table set-up, including hollow capillary fiber and chirped mirrors.

The pulse characterization is performed using a home-built SD-FROG, shown below, in addition to the 3-D printed masks we use to perform the measurement.

The home-built SD-FROG and 3-D printed masks.

The native Carbide output (1030 nm) is characterized using SHG-FROG, which is shown below.

SHG-FROG of the fundamental output from the Carbide. We measure a roughly 275 fs pulse.

The second harmonic of the native Carbide output (516 nm) is characterized using SD-FROG, which is shown below.

SD-FROG of the second harmonic of the Carbide. We measure a roughly 128 fs pulse.

The fourth harmonic of the native Carbide output (258 nm) is characterized using SD-FROG, which is shown below.

SD-FROG of the fourth harmonic of the Carbide. We measure a roughly 114 fs pulse.

Next, we perform spectral broadening and post-compression of the Carbide, which is then used to generate shorter pulse harmonics in bulk crystal. Below is the spectrally broadened output of the Carbide laser for different hollow capillary fiber gas pressures.

The spectrally broadened output of the Carbide laser for different hollow capillary fiber gas pressures.

The spectrally broadened Carbide output is characterized using SHG-FROG, which is shown below.

SHG-FROG of the spectrally broadened output from the Carbide. We measure a roughly 29 fs pulse.

The second harmonic of the spectrally broadened Carbide output (516 nm) is characterized using SD-FROG, which is shown below.

SD-FROG of the second harmonic of the spectrally broadened Carbide. We measure a roughly 16 fs pulse.

The fourth harmonic of the spectrally broadened Carbide output (258 nm) is characterized using SD-FROG, which is shown below.

SD-FROG of the fourth harmonic of the spectrally broadened Carbide. We measure a roughly 20 fs pulse.