Laser 4 Aton: 10 PW, 2 kJ

The L4 Aton beam line is designed to generate an extremely high and unprecedented peak power of 10 PW (Petawatt) during pulse duration of about 130 fs. The uncompressed energy can reach almost 2 kJ with a shot rate of 1/min, which is a major step in the field of kJ-class lasers. The architecture is based on direct compression of a broadband beam amplified by a combination of different Nd:glass slabs.

The L4 Aton system architecture

The L4 laser system can operate in two main modes:

All the energy can be used to generate a power of 10 PW in a single beam. By-pass of the compressor is possible in order to use the chirped nanosecond (ns) beam directly.

The main amplifier can deliver almost 2 kJ in a narrowband ns beam with variable temporal shaping seeded by a separate front end. At the same time, the broadband front end can seed the first main amplifier and thus provide a 200 J-class PW pulse.

The L4 laser chain is composed of a broadband ultrafast oscillator, picosecond OPCPA preamplifier, nanosecond OPCPA stages, and two main amplifier stages based on Nd:glass-gain media pumped by flashlamps. The resulting nanosecond pulses are compressed in a dielectric grating compressor.

L4 beam line design parameters (main beam)

Output pulse energy (main beam compressed)	>1,800 J in single aperture
Pulse duration (CPA regime)	<150 fs FWHM (adjustable to 100 ps)
Pulse duration (non-CPA regime)	0.5–5 ns (temporal shaping adjustable in 150 ps steps)
Repetition rate	1 shot per minute
Peak power	10 PW
Pump laser technology	flashlamp-pumped Nd:glass amplifiers
Output laser pulse energy RMS stability	better than 10% rms
Output laser beam RMS pointing stability	<10 µrad
Laser control system	Labview and EPICS
Output pulse external synchronization relative to the facility clock	<20 ps to RF clock with any delay relative to facility clock
Beam format	rectangular superGaussian
Beam size of compressed beam	<550×550 mm

L4 current parameters
Short Pulse beamline (CPA regime)

Output pulse energy	>1,500 J
Pulse duration (CPA regime)	~150 fs FWHM
Central wavelength	1060 nm
Maximum Repetition rate	1 shot per minute
Front-End Energy / repetition rate	4.8 J / 5 Hz
Pump laser technology	flashlamp-pumped Nd:glass amplifiers
Output laser pulse energy RMS stability	better than 2.5% RMS
Output laser beam RMS pointing stability	<8 µrad
Laser control system	Labview and EPICS
Output pulse external synchronization relative to the facility clock	<20 ps to RF clock with any delay relative to facility clock
Beam format	square super-Gaussian
Clear Aperture of compressed beam	650×650 mm

L4 current parameters
Long Pulse beamline (Non-CPA regime)

Design Output pulse energy	>1,900 J
Pulse duration (Non-CPA regime)	150 ps to 10ns (pulse shaping with 150ps step and high double pulse contrast)
Central wavelength	1053 nm
Maximum Repetition rate	1 shot per minute
Front-End Energy / repetition rate	30 J / 1 shot per minute
Pump laser technology	flashlamp-pumped Nd:glass amplifiers
Output laser pulse energy RMS stability	better than 2.5% RMS
Output laser beam RMS pointing stability	<8 µrad
Laser control system	Labview and EPICS
Output pulse external synchronization relative to the facility clock	<20 ps to RF clock with any delay relative to facility clock
Beam format	square super-Gaussian
Clear Aperture of output beam	323×323 mm
Auxiliary CPA Beam Energy / Pulse Duration	100 J / 150 fs

Delivery of the system

The delivery of the L4 Aton laser system was contracted with the United States-Lithuanian consortium of National Energetics and EKSPLA in September 2014.

The main subcontractors are Schott and Lawrence Livermore National Laboratory.