0
1.1kviews
What does the coupling efficiency equation? $\eta = (pf / ps) =(NA)^2$ signify where pf is the power coupled to the source ps source power.
0
3views
1. The coupling efficiency is defined as a measure of amount of power emitted from an optical source that can be coupled into a fiber.

$\therefore$ Coupling efficiency

# $ɳ_c = \frac{P_{fiber}}{P_{source}}$

where

$P_{fiber}$ is the power coupled into the fiber

$P_{source}$ is the power emitted from source

1. The coupling efficiency also depends on the type of fiber.

2. Many suppliers offer optical sources along with a short fiber already coupled to the source.

3. This small section of fiber that comes along with the source is called as “flylead” or “pigtail”.

4. case 1:

$$ɳ_c = \frac{P_f}{P_s} = (NA)^2$$

$$NA = sin θ_a$$

$P_s$ = power emitted from the source

$= π^2.r_s^2.B_0$

$B_0$ is the Axial radiance

6. Case II:

$r_s\gta$

$P_f =(\frac{a}{r_s} )^2.P_s .(NA)^2$