Question

4.32 Laser diode efficiencies Consider a commercial InGaAsP FP laser diode (Mitsubishi ML720 and 725 seriesi operating at ?-1310nm for optical communications. The threshold current is 5 mA. At 1 20mA, the out- put optical power is 5 mW and the voltage across the diode is 1.1 V. Calculate external quantum efficiency (OE), external differential QE, power conversion efficiency, and the slope efficiency of the diode. What is the forward diode current that gives an output optical power of 2 mW?

Answer 1

Given that * let us consider a commercial laser diode operating at lambda = 1310 m m for optical communication * Threshold current is At f = 20 m A * The output optical power is 5 m v * The voltage across the diode is 1 . 1 v a) Required to calculate the external Quantum efficiency: - rightarrow External Quantum efficiency = optical power/h v/Diode current/e rightarrow P_ 0/E_ g/I/e rightarrow External Quantum efficiency = e p_ 0/I E_ g Here: - E = h v = proton energy E = h v = 6 . 625 times 10 ^- 34 times 3 times 10 ^8/1310 times 10 ^- 9 m (Because h is c one constant values) E_ g = 0 . 015 times 10 ^- 17 * Now external Quantum efficiency = 1 . 602 times 10 ^- 9 times 5 m/20 times 0 . 015 times 10 ^- 17 where P = Threshold current = 5 times 10 ^- 3 e = 1 . 602 times 10 ^- 9 (constant value)