How to calculate the energy of the second harmonic pulse and efficiency of the conversion process?

Consider second harmonic generation at the fundamental frequency corresponding to the wavelength of 1 \mu m( 10^{-6} m). Assume that the length of the laser pulses is 10 ns, energy 10mJ, and beam diameter 1mm. The effective nonlinear coefficient, the index of refraction, and the thickness of the crystal are \chi^{(2)} = 10^{-8}esu, n=1,5, and L = 1mm, respectively. Assume also that the interaction is perfectly phase-matched(\Delta k = 0 ). Calculate
(a) the energy of the second harmonic pulse
(b) the efficiency of the \omega→ 2*\omega conversion process \eta=I_2(L)/I_1(L), where I_{1,2}(L) are the output intensities of the fundamental and second harmonic beams.