<180 fs pulses
Average power 6 W
Flexibility in repetition rate - 1 to 350 kHz
Sealed oscillator and amplifier modules
Interchangeable pump modules
Broad range of frequency conversion options (harmonic generators , OPA)
Low running and maintenance costs
PHAROS is a Yb:KGW based system that delivers power sufficient for a number of materials processing applications and has a pulse duration short enough to make it attractive for the research community.
Design and performance
PHAROS is built upon traditional chirped pulse amplification concept, employing the seed oscillator, regenerative amplifier and pulse stretcher/ compressor. The oscillator is Kerr lens mode-locked with chirped mirrors used for group velocity dispersion compensation. Typical average output power of the seed oscillator is in excess of 700mW with sub-100 fs pulse duration. The laser crystal of the regenerative amplifier is non-collinearly pumped by two high brightness custom designed diode bar modules that deliver up to 50W at 980nm. Low loss BBO Pockels cell supports the operation at repetition rates up to 350kHz. The average power at repetition rates above 100kHz exceeds 6W. Maximal pulse energy for standard systems is 0.4mJ and can be increased beyond 1mJ using different cavity design that is less efficient at high repetition rates. In the standard PHAROS the output pulse duration is 280fs, somewhat varying with the repetition rate due to change in saturation level of the laser crystal. In PHAROS-SP (Short Pulse) spectral pre-shaping of the high power seed leads to nearly doubled bandwidth that is sufficient to support ~100fs pulses. The shortest pulses we obtained so far were about 170fs in Gaussian fit. The stretcher/compressor unit employs transmitting gratings that exhibit high efficiency and excellent power handling capability.
Mechanics and electronics
The opto-mechanical design of the PHAROS features sealed modules of oscillator, regenerative amplifier and stretcher/compressor, and has very small footprint (570x400mm). This foot print includes a space for harmonic generators and Pulse Picker. For OEM applications the sealed modules can be used without external box with reduced space required (480x210x280mm).
Timing electronics is placed near amplifier unit. It controls switching of Pockels cells of the regenerative amplifier and pulse picker and provides protection against optical damage of laser crystal by high intensity pulse. Power supply box (520x520x320mm) includes drivers for laser diode bars, and HV supply for Pockels cell driver. The complete system is controlled by the set of microcontrollers linked together by industrial CAN bus. Parameters of the laser can be set and monitored using Remote control pad or external PC via USB interface. Extensive software control is used for setting the operation parameters as well as for long-term stabilization.