69-0081-18_spec_femtosecond_laser_8-03-18.docx

SPECIFICATIONS FOR TURNABLE LASER SYSTEM

PR69-0081-18

The Turnable Laser System will be used to carry out mission critical, ONR funded, experiments to elucidate and understand the nanoscale physics of the ultra-fast, non-thermal, welding of plasmonic nanoparticles into IR nanoantennae. This system will be used also be used to manufacture these IR nanoantennae in bulk quantities. The system must be robust, as specified below, due to the long run times and have sufficient protection to survive operating in harsh environments (e.g. NRL infrastructure, Blue Plains, etc).

To accomplish the above tasks, the system must have the following requirements:

1. A continuously tunable (480nm-2600nm) pulsed laser system with large pulse energies across the entire tuning spectrum.

2. Pulse energy must be greater than 7 mJ and pulse width must be less than <100 fs.

3. Center wavelength must be 800 nm.

4. Pre-Pulse Contrast Ratio must be > 1000:1 and Post-Pulse Contrast Ratio must be > 100:1

5. Power Stability must be <0.5 % rms measured over 24 hours.

6. Beam pointing stability must be <10 rad rms measured over 24 hours.

7. Polarization must be linear, horizontal.

8. Beam diameter must be 11mm nominal.

9. Beam mode quality must be TEM00 and better than: M2 < 1.3

10. 40% conversion to parametric light at peak.

11. Lockouts must be standard Vitara.

12. For reliability, maintainability and simplicity the Ti:sapphire rod in regen needs to be water-only cooled (no TEC)

13. Older round-rod based Ti:S rod will be avoided, rather slab Ti:S rod design for the most efficient cooling should be used to improve cooling efficiencies.

14. The Regen pump laser needs be in same enclosure as amplifier

15. Water-cooling needs to be used for all systems and sub-systems (osc, pump, regen, S/C) to stabilize the temperature. The water cooling should come from 1 chiller (except if Vitara-T-HP is used for oscillator)

16. Shielded high-speed drivers that are water-cooled must be used on the system.

17. For maximum stability no regen optics will be mounted using posts off the sub-plate. All regen optics need to be mounted directly to temp-stabilized baseplate

18. To enhance the reliability and stability, the stretcher-compressor assembly must be O-ring sealed, which requires input and output windows on S/C assembly.

19. For independent control of injection of the seed pulse and ejection of the amplified pulse, 2 Pockels cell in regen must be used and they must be shielded with Faraday cages.

20. Must have capability to have a tunable closed box seed oscillator which produces >70nm of bandwidth.

21. The oscillator must have the capability to be locked to an external reference clock.

22. Must have capability of a CEP compatible oscillator.

23. To provide longer life, the pump laser must be capable of operating at de-rated power and be specified at >38 mJ to provide larger operational headroom.

24. Long term pulse stability must be demonstrated without recourse to active compensation systems, potentially conflicting with data collection.

25. A robustness and optimum reliability assessment (HASS testing or equivalent) should be carried out on the amplifier system, including the oscillator, pump, regen and stretcher/compressor

26. Procedures should be developed as an ongoing product development program to carry out highly accelerated life tests (HALT or equivalent using (HALT/HASS type procedures).

27. Due to volatile organic compounds in the air at NRL, which attach to and degrade the optical elements, we require that the stretcher and compressor gratings in the regenerative amplifier be shielded from these airborne pollutants.