Quantum Well Lasing: Solve the Problem Now!

[DengYang]

Hi everybody, I want to solve this problem but I'm stucked with several equations all over the books, if anybody is expert in lasing please help me!

We want to make a laser at ħω=Ec-Ev. Assume that the mirror reflectivity is [(n-1)^2] / [(n+1)^2] , where n=3.5 is the refractive index of InGaAsP, the internal loss of the laser cavity is very small, and the confinement factor is 0.02 (the power of lasing field in the QW divided by the total power in the laser cavity), calculate the threshold gain of QW in order for the laser to lase. Ec - Ev is 1.3636 eV
thank you!

 

[Asim Riaz]

The threshold gain is given by the following equation:Gthreshold = (2πn)/[(1-R)λ] Where R is the reflectivity of the mirror, n is the refractive index of the medium, and λ is the wavelength of the lasing field.Substituting the given values, we get:Gthreshold = (2π*3.5)/[(1-(n-1)^2/(n+1)^2)*1.3636eV] Gthreshold = 11.7 cm-1