Let us consider the behaviour of a monochromatic laser beam that is coupled into
ID: 1998467 • Letter: L
Question
Let us consider the behaviour of a monochromatic laser beam that is coupled into an optical fibre.
a) The beam is coupled into a multimode fibre. After the optical wave travels for a certain distance in the fibre, the diameter of the fibre shrinks to become a single-mode fibre. What will happen to the optical field in the fibre? Are all of the different mode components of the optical field still there?
6) Now the beam is initially coupled into a single-mode fibre. After a certain distance, the fibre expands to become a multimode fibre. What happens to the optical field in the fibre?
Explanation / Answer
Singlemode fiber has a much smaller core, only about 9 microns, so that the light travels in only one ray (mode.) it has lower loss and virtually infinite bandwidth.
a) Since the Light is a monochromatic laser beam, after travelling a certain distance there is no major loss in the mode components of the optical field
b) Since the beam is initially coupled into a single-mode fibre there are no losses, but after entering into a multimode fibre there are certain losses and interference but there will be no loss in the mode components of the optical field.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.