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 :

ɳ

ɳ

_{T}= Total number of output electron / Total number of injected electrons
ɳ

_{T}= Pe / I. Eg
Pe / I = ȠT . Eg

ɳ

_{T}= 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.

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 :

ɳ

ɳ

_{T}= Total number of output electron / Total number of injected electrons
ɳ

_{T}= Pe / I. Eg
Pe / I = ȠT . Eg

ɳ

_{T}= 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.