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Terawatt picosecond (TWps) 2-laser for fundamental
and applied investigations - MIRPILAF



Technical prospects based on the ISTC Project # 2521
- NIIEFA (Saint-Petersburg)
- NIIKI OEP (Sosnovy Bor, Leningrad region)

Project Collaborators:
Mr. J.-Claude de Miscault, CILAS (France)
Prof. Willy L. Bohn, DLR (Germany)

Mid-InfraRed Picosecond Laser Facility MIRPILAF - ISTC # 2521

Facility developed:
  • High Pressure Amplifier of short laser pulses (up to 10 atm)
  • Picosecond CO2-laser master oscillator (MO) with pulse power of 1 MW and pulse duration of 100 ps
  • Equipment for recording of picosecond laser pulses
Mid-Infrared Picosecond Laser Facility is considered as a multi-atmosphere terawatt picosecond (TWps) CO2-laser being developed on a basis of "MO-Pre-A-PA" design.

Master oscillator schematic diagram, including apparatus for recording of the laser pulse characteristics




Hybrid 2-laser





Laser characteristics:
  • CO2:N2:He - 1:1:7 gas mixture
  • specific energy input into a gas discharge - 220...300 J/l
  • maximal peak power of the laser output > 0.8 MW
  • pulse duration ~ 400 ns

Picosecond Nd-laser to control optical switches





Nd-laser characteristics:
  • Output energy: 3...5 mJ
  • Beam diameter: 2.8 cm
  • Pulse duration: 1...2 ps

Ge optical switches





Generation of picosecond CO2-laser pulse with a variable pulse width by using of Ge optical switches controlled by picosecond Nd-laser pulses

Master oscillator units



Controlling Nd-laser




Streak camera




Hybrid 2-laser




Up-conversion equipment



Master oscillator pulse characteristics



Hybrid CO2-laser pulse passed through Ge-switch (upper track),
and controling Nd-laser pulse (lower track).




Master oscillator pulse registered
by a streak camera.




Temporal profile (power temporal shape) of the master oscillator pulse


Results

  • Pulse width of the Master Oscillator pulse changes from 10 ps to 100 ps, depending on the delay between controlling pulses
  • Maximal pulse peak power - 0.8 MW

Fields of application of TWps CO2-lasers

Super strong light fields Generation of ultra short laser pulses High-power laser ablation
  • Laser-guided lightning P ~ 1 TW, t ~ 100 ps...1 ns
  • Laser acceleration of electrons P ~ 10 TW, t ~ 10 ps
  • X-ray picosecond pulses I~1016 W/cm2, t ~ 1 ps
  • Multi-charged ions for acclerators I ~ 1015 W/cm2, t ~ 1 ps
  • Non-traditional recoverable power sources on the basis of laser ablation of metal oxides P~1 TW, t ~ 10 ps
  • Creation of energy closed circuit



Schematic diagram of laser accelerator of electrons Plasma channel generated in the atmosphere by laser Generation of high-power ion beams



2-laser ring amplifier controlled by a Nd-laser.
Optical schematic diagram.

Principal pulse characteristics of the amplifier:
  • Laser beam aperture: up to 1.5 m
  • Power amplification: 105-106
  • Input pulse power: ~ 1 MW
  • Output pulse power: > 100 GW (up to 0.5 TW)
  • Output pulse width: ~ 10 ps

Self-development of a single pulse out of a pulse train*
  • unidirectional mode of radiation generation
  • active medium with a reduced gas pressure of 3 atm
  • power pumping pulse of 5 ms duration, providing multi-pass amplification (a(0)×z=90) of the laser pulse to maintain the self-development process
*V.T. Platonenko, V.D. Taranukhin. Coherent amplification of light pulses in a medium with a discrete spectrum. Quantum Electronics, Vol. 10, No. 11, 1983

2-laser ring amplifier controlled by a Nd-laser. Numerical model.

Theoretical model of the pre-amplifier is based on a numerical solution of a set of equations describing a) slowly oscillating amplitude of electric field of a light wave propagating in the laser medium, b) active medium polarization, and c) population inversion.
It is assumed that an input pulse has a Gaussian temporal shape with a width of 5, 20, and 100 ps by -2 intensity level. It is assumed the signal shape does not change, and it meets the Gaussian self-reproducing beam with an area of 1 cm2 in the active medium region. Amplitude of the input signal is equal to 6×105 V/m that corresponds to radiation intensity of 105 W/cm2.
The laser medium is described by eleventh resonance spectral lines with a central one corresponding to a wavelength of 10.59 mm. Polarization cross relaxation rate is assumed to be of 2 = 27 ps, and molecular rotation relaxation rate is R = 67 ps if the gas pressure is 3 atm. Saturation intensity is of 270 MW/cm2 if the input pulse is of 100 ps. But the saturation intensity increases inversely a square of the pulse width.

Temporal shape transformations of the laser pulse propagating in the CO2-laser ring preamplifier



2-laser ring amplifier design



Laser amplifier supply system parameters:
  • Supply voltage pulse width: 5 ms
  • Supply pulse energy: 3 kJ
  • Amplifier active gas pressure: 3 atm
  • Gas discharge gap: 3 cm
  • Controlling Nd-laser pulse width: 10 ps
  • Controlling Nd-laser pulse energy: ~ 300 mJ

MIRPILAF, technical prospects



MIRPILAF, technical prospects (case A)



MIRPILAF, technical prospects (case B)



MIRPILAF, technical prospects (case C)



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