Write the rate equations for all four levels of Problem 17. Write the rate equation for the photon number within the laser cavity for the system described in Problems 17 and 18. Given a 20%...

Write the rate equations for all four levels of Problem 17.

Write the rate equation for the photon number within the laser cavity

for the system described in Problems 17 and 18.

Given a 20% transmittance output coupler for a laser has a diameter

of 1 cm, the length of the cavity is L = 10cm, the length of the gain

medium is l = 7cm, the wavelength of the laser is 532nm, the index of

refraction of the gain medium is n = 1.2, and the output irradiance is

10mW/cm2. What is the number of photons in the cavity? (Hint: use

Equation 4.62)