(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A laser produces 15.6 dBm of power. The light is propogated through a 10dB neutral density filter that attenuates the signal so that it can be detected by a photodiode without saturation. The optical signal is steppeddown by 15dB when captured by teh photodiode and coverted to an electric signal. This signal is later amplified by 20.2 dB by an inverting amplifier. What is the output signal power from teh amplifier in mW?

2. Relevant equations

[tex] G [dB] = 10 \log_{10} \left(\frac{P_{out}}{P_{in}}\right) [/tex]

where P is the power

[tex] G [dBm] = 10 \log_{10} (P[mW]) [/tex]

3. The attempt at a solution

15.6 is in dBm while the others are in dB. How do we convert from dBm to dB??

Since G represents the gain or loss

then the total gain by the signal is -10 - 15 + 20.2 = -4.8

Thus we would use hte first equation

with G = -4.8 , Pin = 15.6 dBm and calculate Pout

would that be correct??

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Gain/loss of a laser power

**Physics Forums | Science Articles, Homework Help, Discussion**