how to draw laser signal power spectrum from it's phase noise spectrum(dBc/Hz)

[sunshineshuvo]

Hello, i have a laser phase noise data as
-50dBc/Hz @ 1KHz
-70dBc/Hz @ 10KHz
90dBc/Hz @ 100KHz
now from these data how can i draw a lase power spectrum(dbm)

thanks

Reza

 

[biff44]

Have not been keeping current in laser technology, but that sounds like incredibly good phase noise for a laser. What type is it?

But, assuming the values are correct. phase noise is measured in dBc/Hz, which is shorthand for saying "db below the carrier in a 1 hz bandwidth".

Example: if you have 10 mW of laser power, that would mean the "carrier" was at +10 dBm. At 1 KHz offset from the carrier the noise power in dBm would be +10dBm -50 dB = -40dBm in a 1 hz bandwidth.

There is a slight issue of if the noise you measured is single sideband or double sideband (3 dB difference).