- An engineer has two Ga(1-x)Al(x)As LEDs: one has band gap energy of 1.540 eV and the other has x = 0.01. find :
a. Al fraction (x) and emission wavelength of LED1
b. Eg and emission wavelength of LED2
answer :
a. Eg = 1,424 + 1.266X + 0.266X^2
1.540 = 1.424 + 1.266X+0.266X^2
X = 0.09
LED1 = Ga(0.91)Al(0.09)As
Emission Wavelength :
b. Eg = 1.424 + 1.266X + 0.266X^2 = 1.424 + 1.266(0.015) + 0.266(0.015)^2
= 1.4430 eV
- A double heterojunction InGaAsP LED emitting at a peak wavelength of 1310 nm has radiative and nonradiative recombination time of 25 and 90 ns, respectively. The drive current is 35 mA.
a Find the internal quantum efficiency and the internal power level.
b. If the refractive index of the light source material is n = 3,5, find the power emitted from the device.Asnwer :
a.
b. power emitted from device (Po) = n^2 = 3.5×3.5=12.25W - a GaAl As laser diode has a cavity length which has an effective absorption coeffient of 10 cm-1. For the uncoated facets the reflectives are 0.32
a. What is the optional gain at the lasing threshold?
b.If one end of the laser is coated with a dielectric reflector so that its reflectivityis now 90%, what is the optical gain at the lasing threshold?
c. If the internal quantum efficiency is 0,65, what is the external quantum effiency is cases (a) and (b)?
answer :
a.
b.
c. untuk kasus a
untuk kasus b 
- belum selesai … nyusul 🙂
