Photocathode Laser successfully tested at ELI-NP

The ELI-GBS LINAC system uses a high-performance laser system for its photocathode RF Electron Source. The photocathode laser (PHAROS PH1-06-1500-02-42 from Light Conversion with 71.4 MHz oscillator frequency and 135 μJ pulse energy) emits short pulses of UV light in order to free electrons from the Cu photocathode through photoelectric effect.
In order to accurately measure the characteristics of the laser system, an ISO 6 compatible clean room was built at ELI-NP during 2023. The photocathode laser was installed inside the cleanroom during 2024.
After installation, the main characteristics of the photocathode laser were measured:

Average optical power in both IR and UV

UV and IR spectrum measurements

Beam profiles

Laser oscillator frequency stability, long term and short term

Laser oscillator frequency adjustment limits

Laser pulse duration

Electrical spectrum of laser oscillator detected by a high-speed photodiode

All measurements were completed by the end of December 2025.

Measuring the characteristics of the photocathode laser inside the ISO-6 clean room