Ultrashort pulse lasers present a class of laser beam sources for industrial applications that offer outstanding features with respect to intensity, photon density
and pulse duration.
where r denotes the position, [PHI] is the photon density
, Q is the source term, and [u.sub.a] D are the absorption and diffusion coefficients, respectively.
[phi](r, t) photon density
at ([m.sup.-3]) point r, at time t 10.
In this case, the key factor that determines nonlinearity is photon density
. At the same time thermal effect also plays an important role in cell damage due to high single-photon absorption by water and heat generation in nonlinear processes.
This is paramount because the probability for a photon absorption event to occur largely depends on the photon density
or fluence rate and the photon absorption cross section of the molecule where the former may be influenced by the pulse repetition rate and the peak power.
Here [L.sub.p] = [(Gh/[c.sup.3]).sup.1/2] is the Planck length, [n.sub.c] = [u.sub.c]/[bar.E] a characteristic photon density
, and [bar.[lambda]] = c/[bar.v].
Based on a multi-layered semiconducting structure, which serves as a medium to build up photon density
that can also be tailored to emit at different wavelengths, the QC laser has proven to be a compact, useful light source for many applications.