, including research setups and adaptations, permit to experiment the idea early
- while pulse energy, mean power, wavelength for industrial production will need special lasers. Ask an optician for better advice.
I gave examples for exciplex lasers
. They exist and deliver power at interesting wavelengths directly, but the ones that process semiconductors take a room and M$ for 60W output in long pulses. Other exciplex designs may fit better.
Solid state lasers seem more adequate. They are compact, can provide short pulses in modelock operation, but their output wavelength needs a frequency multiplier that wastes much power, and the oscillators appear to give few watts at most, so several amplifier crystals (typically 6mm*3mm*3mm plus cooling) would follow to bring the desired pulse energy and mean power.
Among them, Modelocked Ti:sapphire
lasers offer pulses as short as desired: <10fs to >1ps.http://www.rp-photonics.com/titanium_sapphire_lasers.html
They typically provide mean 1W, and 800nm needs a tripler (to target iodine) or two doublers (bromine). The pulse energy, like 10nJ, isn't brilliant neither. Worse, their pump is an already inefficient pulsed laser.
The best fit among today's zoo seems to be modelocked vanadate lasers pumped by laser diodes
Diode modules exist for 800W and more, about 1/2 efficient, and the vanadates can convert 1/3 of it. Nd:Vanadate outputs 1060nm, so F*3 serves little, F*4 targets iodine well, and F*5 bromine. Nd:YVO4
is more usual, but Nd:GdVO4
is more powerful, and the uncommon Nd:LuVO4
pumped by a laser diode and followed by a KTP crystal doubler make green laser pointers. The power doesn't correspond, but their compact rugged design resembles what we need - just bigger... The attached diagram is gratefully pinched at Wikihttp://en.wikipedia.org/wiki/Neodymium-doped_yttrium_orthovanadate
produces 5W at 1064nm as 107MHz 47nJ 6.5ps from 50W at 808nm
"High-power picosecond Nd:GdVO4 laser mode locked by SHG in periodically poled stoichiometric lithium tantalate"
by Iliev H1, Buchvarov I, Kurimura S, Petrov V.
while that Nd:YVO4
produces 2.5W at 1064nm as 4MHz 640nJ 17ps from 27W at 808nm
"Stable mode-locked operation of a low repetition rate diode-pumped Nd : GdVO4 laser
by combining quadratic polarisation switching and a semiconductor saturable absorber mirror"
by Christoph Gerhard, Frédéric Druon, Patrick Georges, Vincent Couderc, Philippe Leproux
Here is a numerical example for two-photons coupling
experiments using vanadate lasers.
With 17ps pulses, a molecule free flight time of 40ps limits unwanted reactions. This corresponds to 300K and 3.6 bar for air, say 2.5 bar
for bigger radicals. -CH2
Br absorbs F*5 = 213nm with 1.5*10-18
section (and BrC2
), or 63% after 110µm.
213nm light concentrated on r=5µm diverge by r+1.4µm at 55µm before and after the focal plane. The irradiated 12400µm3
molecules, and two 5.8eV photons for each need 63% of 2.2µJ, the output of 35 amplifier
after 10% upconversion. Cumulated 9W treat 0.44mol in 24h, that's 30g housane
Marc Schaefer, aka Enthalpy