Answer :
To solve this problem it is necessary to apply the related concepts laser pulse energy.
By definition the energy of a laser pulse in terms of number of photons is
[tex]E = N \frac{hc}{\lambda}[/tex]
Where,
[tex]\lambda =[/tex] Wavelength
N = Number of photons in each laser pulse
h = Planck constant
c = Speed of light
We need to find the wavelength, then re-arrange the equation we have
[tex]\lambda = \frac{Nhc}{E}[/tex]
Converting the unit the energy from J to eV, we have
[tex]E= 1*10^{-3}J(\frac{1eV}{1.6*10^{-19}J})[/tex]
[tex]E = 6.25*10^{15}eV[/tex]
Replacing,
[tex]\lambda = \frac{Nhc}{E}[/tex]
[tex]\lambda = \frac{(9.7*10^{14})(4.136*10^{-15})(3*10^8)}{6.25*10^{15}}[/tex]
[tex]\lambda = 192.4nm[/tex]
Therefore the wavelength of the laser is 182.4nm
Note: The Planck constant used is in units of eV.