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Unformatted text preview: density, J th . (d) If the pump current is 15mA, what is the number of photons generated per second? 7. The laser threshold current has been reduced substantially since the inception of semiconductor laser in the 1960s. State what have contributed to this reduction. 8. If a laser has a threshold current at 15mA and a maximum output power 0dBm at 65mA. Assume the P-I curve is linear when operates above the threshold current. (a) Find an expression for the output power (in mW) with a sinusoidal input 40+5cos( ω t) mA. (b) If now the laser is not perfect with d 2 P/dI 2 | I=40mA =0.005 (W/A 2 ). Use Taylor series expansion for P(I)| I=40mA and then find the corresponding optical power (in mW) of the second harmonic term (at 2 ω ) and the 2 nd-order Harmonic Distortion (in dB). ~~ END ~~...
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- Spring '10