Maximum length of an optical fiber

[yoni3468]

Hi all,

I have a question regarding a fiber optics based communications system:
The light source is a Fabry-Perot LASER, which outputs 5 longitudinal modes.
The communication rates are: $$\Delta\omega$$=100Grads$$^{-1}$$, B=10Gbs$$^{-1}$$, and the dispersion coefficient is $$\beta_{2}$$=10$$\frac{ps^{2}}{Km}$$.

What is the maximum distance of transmission we can use this system for (without using any amplifiers)?

The answers are phrased in a nutshell, and the answer is:

BLI|$$\beta_{2}$$|(4$$\Delta\omega$$) $$\leq$$ 1 $$\Rightarrow$$ L=25Km.

I have never seen this equation (What is I?). Can anybody try to explain?

Thanks in advance.

 

[Valkarie]

The equation refers to the Boundary Line of Integrity (BLI). The BLI is a formula used to calculate the maximum distance that an optical signal can travel without significant distortions. It is defined as:BLI|\beta_{2}|(4\Delta\omega) \leq 1Where \beta_{2} is the group velocity dispersion coefficient and \Delta\omega is the frequency shift between the different longitudinal modes of the laser.In this case, BLI|10\frac{ps^{2}}{Km}|(400Grads^{-1}) \leq 1 \Rightarrow L=25Km.This means that the maximum distance of transmission that can be achieved with this system is 25 kilometers without using any amplifiers.