Optical vs Electrical Bandwidth

[wafi_zuhdi]

Hi,

I'm a little confused about the difference between optical bandwidth and electrical bandwidth. The -3db optical bandwidth = -6db electrical bandwidth if i'm correct?

for the sake of argument, let say i'm measuring the bandwidth of an LED using a photodiode. the mesurement i'm getting from the photodiode is the electrical signal rather the optical signal. So the bandwidth of the LED would be the signal's -6db attenuation i'm getting from the photodiode. Am I correct? or do i get this totally wrong?

thanks

 

[rahdirs]

Re: optical vs electrical bandwidth

• The electrical bandwidth or -3dBe of the detector is then defined as the frequency at which the electrical power spectrum drops to 50% (or -3 dB) of its value at DC.
• Since the output current, or voltage, is proportional to input optical power, the point at which the voltage spectrum falls to 50% of its DC value is known as the optical bandwidth, or -3dBo.

Thus,in electrical regime the 3db bandwidth may be defined by the frequency when the output current has dropped to 1/sqrt(2) of the i/p current of system.

So,depends on frequency