n = 65%
panjang gelombang = 900nm
Po = 0.5uW
Im = 10uA
q = 1,6×10^-19

tentukan u ??

jawab:
R= (n.lamda.q)/hc = (0.65x900x10^-19)/(6.625×10^-34x3x10^8)= 0.47
Ip = R.Po = 0.47×0.5=0.235

u = Im/Ip = 10/0.235 = 42.553

1. 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
   
   

2. 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

3. 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 
4. belum selesai … nyusul 🙂