This article is very useful to know or learn about how to find different types of efficiency in the laser diode.
1. External quantum efficiency :
The operational efficiency of the semiconductor laser is differential external quantum efficiency. It is the ratio of the increase in photon output rate for a given increase in the number of injected electrons.
ȠD = dpe \ dI( Eg)
Where,
pe = Optical power emitted from a device
I = Current
Eg = Band gap energy expressed in terms of electron volts
2. Internal quantum efficiency :
The internal quantum efficiency for a semiconductor laser is defined as ɳ given below :
ɳ = Number of photons generated in the laser cavity / Number of injected electron
The optimal value of internal quantum efficiency Ƞi is ranging between around 50 to 100 %.
3. Total efficiency :
The total efficiency is defined as :
ɳT = Total number of output electron / Total number of injected electrons
ɳT = Total number of output electron / Total number of injected electrons
ɳT = Pe / I. Eg
Pe / I = ȠT . Eg
ɳT = ȠD ( 1 - Ith/I )
Where Ith - threshold current
I - injection current
4. External power efficiency
It is in converting electrical input to optical output is expressed as
Ƞep = Pe / P * 100
Ƞep = Pe / IV * 100
Ƞep = ȠT ( Eg / V ) * 100
The Ƞep is also called as device efficiency.
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