Answer Happy

- Problem 2.3 (37.5 points) (Optical communications laser) You are designing a VCSEL laser based on In Gal xAsyP1-y - InP, for which In Ga1-xAsyP -y, 52 micrometers thick, is the active layer, while alternating layers of InxGa1-xAsyP1-y (of the same composition as the active layer) and InP form the dielectric mirrors. The bandgap and index of refraction for In GalxAsyP1-y (with y =(1-x)/0.465) are given by the equations below, while the absorption is given by the curve on the right: 1x108 In GaAsP 1x107 E (V)(V) = 1.35 -0.72 y +0.12y2 8 1x106 (m-1) 2.054 n(y) = 6.287+ 1.35 1- 0.6245 a[um]. E. (y)[eV] 1x105 1x104 1x103 02 0.4 0.6 0.8 LO 12 14 1.8 16 Wavelength (um)
(d) What is the spectral separation between the modes of the cavity at around 1300 nm? (e) If the gain curve of the active layer has a width of about 30 nm how many modes are emitted by the laser? (1) If the reflectivity of the back dielectric stack is about -100% and the reflectivity of the output dielectric stack is -90 % calculate the threshold gain for this laser. (g) If the carrier lifetime is tap-10 ps, calculate the threshold population inversion