2004 EE 164 Problem Set 3 Solution

2004 EE 164 Problem Set 3 Solution - EE 164 Problem 1...

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EE 164 Problem Set 3 Spring 2004 Problem 1 An LED device composed of GaAlP semiconductor material is emitting at a wavelength of 650nm. Calculate the bandgap energy for the above material. Since , solving for cg g hc E E λ = () ( ) 34 17 19 6.63 10 3 10 3.09 10 650 g c Js nm s hc EJ nm ×× == = × In eV, 19 19 3.09 10 1.91 1.6 10 geV J Ee V C × × 1.91 g E eV = Problem 2: If an optical source coupled to a fiber is forward biased with a biasing voltage of 1.75 V will generate a forward current of 24 mV . Assuming diode internal efficiency of 1.5% and coupling angle of 30 ° . a) Find the coupling efficiency. Power input to the source, 24 1.75 42 in F F PIV m A V m W =×= × = 42 in Pm W = Power output of the optical source, int o in P P η = int 0.015 42 0.63 oi n PP m W m W = × = 0.63 o W =
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b) Calculate the optical power coupled into the fiber. The power output of the optical source becomes the optical power at the input of the fiber () 0 in F PP = Efficiency, 2 c NA η = sin 30 0.5 NA = ()() 22 0.5 0.25 c NA === 0.25 c = Power coupled into the fiber, 0.25 0.63 157 Fc i n m WW µ =× = × =
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This note was uploaded on 03/23/2011 for the course EEE 174 taught by Professor Kasab during the Spring '11 term at ASU.

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2004 EE 164 Problem Set 3 Solution - EE 164 Problem 1...

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