1050 nm Fiber Isolator
Chapter 4: Operation
Rev A, January 9, 2019
Page 5
Chapter 4 Operation
4.1. Forward Mode
Laser light enters the isolator via the input single mode fiber. A lens collimates the
light and splits it as it goes through a birefringent beam displacer polarizer. The
light then enters the rotator, which rotates its plane of polarization 45°. It then
passes through a retarder and second displacer polarizer. Finally, it exits via
another collimating lens coupling into output fiber.
4.2. Reverse Mode
Some random beam reflections will be reflected back through the fiber towards the
laser. This feedback enters the isolator and is split by the output beam displacer.
The two beams are rotated 45
by the waveplate and another 45
by the faraday
rotator. The two beams are now oriented 90
as compared to the forward beams
and walk off a second time instead of being recombined. These beams do not
couple into the input fiber and are absorbed inside the isolator housing. The laser
is now isolated from downstream reflections.
Chapter 5 Warranty
All Thorlabs fiber isolators are covered by Thorlabs
’ six-month warranty against
defects in materials and workmanship.
WARNING
Do not attempt to disassemble the isolator.
Disassembly of the isolator voids the warranty and can be unsafe.
Please contact Technical Support if you have questions regarding performance or
operations. See page 9 for contact information by region.
