PSD Parameter in White Light Source

[muhammad jawad]

Dear friends
Plz answer my question as follows

In properties of white light source,there is Power Spectral Density(PSD)parameter.If i tick the check box of PSD and then run a simple simulation and measure the power by power meter at the output of the white light source(when P=-50dBm)then the meter shows power in kW but when i run the same simulation without tick in PSD box and measure the power then the power shows power in mW.What is the significance of PSD box?????Normally what is better to add PSD or not adding the PSD by tick inside PSD box in component properties??

[Aadil Raza]

You only had one or two parameters off from a good simulation! The main issue here was the White Light Source, which was not centered at the correct frequency and the power was much too high (~36W) for the input signal. To fix it I set the center frequency of the white light to 450 nm, which is where your signal band is centered and I unchecked the PSD option and set the average power to 1 mW.

The technical background on the White Light source has more info on the PSD option, but basically when it is checked the power output will be the Power multiplied by the Sample rate. The background information can be found from the Help button on the component properties.

[Aadil Raza]

Read about PSD in following link

awgn noise

[muhammad jawad]

Ok thanks Aadil for reply

Plz let me know the sample rate is dependent on data rate.We cannot alone decrease or increase sample rate rather with data rate.so when data rate is higher,then sample rate is higher.Consequently,noise power is higher when PSD is checked inside box.
I am not getting what you recommended…..again asking in real systems/simulations on optisystems whether we should check or uncheck the PSD option???( plz note that i have to add white light in my simulation)

[Farid Khan]

Jawad.
you can change sample rate even without changing the data rate. just multiply sample rate with 0.1/0.2 or 2,4etc whatever rate you want by changing normal to script mode.
But remember, it sometimes changes the frequency of sinusoidal components. so try it.

[muhammad jawad]

ok thanks i try

[muhammad jawad]

Dear aadil and Farid khan
i still looking the answer that it may be that “PSD off” disables the generation of noise, and “PSD on” enables white noise in optisystems in white light source properties???IF we want to add white noise in a signal then PSD should be off on on????

[Aadil Raza]

Please uncheck i guess and try..

[muhammad jawad]

Dear adil

its works on unchecked but i think noise PSD should be in dBm/Hz.so if checked then after getting multiplied with sample rate,power becomes too high and meter cannot measure such a high power.this is the issue

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