THORLABS IO-F-850 User manual

IO-F-850
Fiber Isolator
User Guide

Table of Contents
Chapter 1 Safety.................................................................................1
Chapter 2 Setup..................................................................................2
2.1. Unpacking ....................................................................2
2.2. Installation Procedure...................................................2
Chapter 3 Description........................................................................3
3.1. Polarization Independent Optical Path Schematic ..........4
Chapter 4 Operation...........................................................................5
4.1. Forward Mode ..............................................................5
4.2. Reverse Mode...............................................................5
Chapter 5 Warranty............................................................................5
Chapter 6 Specifications...................................................................6
Chapter 7 Drawing .............................................................................7
Chapter 8 Regulatory.........................................................................8
8.1. Waste Treatment is Your Own Responsibility.................8
8.2. Ecological Background ..................................................8
Chapter 9 Thorlabs Worldwide Contacts.........................................9

850 nm Fiber Isolator Chapter 1: Safety
Rev B, Sept. 14, 2018 Page 1
Chapter 1 Safety
WARNING
This isolator contains a powerful permanent magnet. Keep all steel objects
and anything affected by a magnetic field at a minimum distance of 2"
(50 mm) from the isolator.
WARNING
Do NOT attempt to disassemble this isolator. The isolator must remain
contained by the isolator body. Any disassembly of the isolator voids the
warranty and can be unsafe.

850 nm Fiber Isolator Chapter 2: Setup
Page 2 17189-D02
Chapter 2 Setup
2.1. Unpacking
Note: Thorlabs aligns the isolator with unpolarized light. This unit is fusion
spliced with the laser source fiber and individually tested. See the included test
report for details.
2.2. Installation Procedure
1) Carefully remove the unit from the box by removing the pins holding the
input and output fibers. Be wary of damaging the fiber when removing
the unit from the box.
2) Place the isolator into your fiber optic system.
3) Secure the base of the isolator to the table via the 4-40 (M3) mounting
slot.
4) Orient the isolator according to the engraving on the lid.
5) Splice the fiber to the source via fusion (recommended) or mechanical
splice.
6) Turn on the power source within the isolator wavelength range (±10 nm
of the center wavelength).
7) Ensure you apply only the maximum rated power of the isolator as
indicated on this spec sheet.

850 nm Fiber Isolator Chapter 3: Description
Rev B, Sept. 14, 2018 Page 3
Chapter 3 Description
Fiber isolators protect light sources from back reflections and signals that can
cause intensity noise and optical damage. Optical isolators, also known as
Faraday isolators, are magneto-optic devices that preferentially transmit light in
the forward direction while absorbing or displacing light propagating in the
reverse direction.
This Thorlabs’ polarization-independent isolator is compatible with single mode
(SM) fibers. There is 0.8 m to 1.0 m of fiber built in to each side of the isolator,
and an arrow engraved on the body indicating the transmission direction. In
addition, each unit is tested before shipment to ensure compliance with our
specifications and a complete test report comes with every serialized part.
An isolator consists of a Faraday rotator, at least two polarizers, a half-wave
retarder and collimating lenses.
The main body of the isolator contains the Faraday rotator, polarizers and
retarder. The outer aluminum sleeves protect the input and output ports
containing the collimating lens and fiber ferrule.
This isolator is mounted on a baseplate with two 4-40 (M3) counterbored slots for
securing the unit to a breadboard or optical table. This base may be removed by
the user if desired. However, do not remove the lid as this is considered
disassembling and will void the warranty.
Part Number
The part number consists of the following:
IO (The Isolator Code)
Letter
oPolarization dependence (F/K –Independent; J/L –Dependent)
oMaximum Power Level (F/J –2W CW max; K/L - 10W CW max)
Center Wavelength (nm)
Example: The IO-F-850 isolator is a polarization independent fiber isolator
with a max power level of 2 W (CW) and a center wavelength of 850 nm.

850 nm Fiber Isolator Chapter 3: Description
Page 4 17189-D02
3.1. Polarization Independent Optical Path Schematic

850 nm Fiber Isolator Chapter 4: Operation
Rev B, Sept. 14, 2018 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.

850 nm Fiber Isolator Chapter 6: Specifications
Page 6 17189-D02
Chapter 6 Specifications
Item #
IO-F-850
Polarization
Independent
Fiber Type
Single Mode (SM), 780HP
Center Wavelength
850 nm
Operating Range
840 - 860 nm
Weight
0.92 kg
Optical Specifications
Isolation @ 850 nm
33 dB (Min)
36 dB (Typ.)
Max Powera
2 W (CW)
Insertion Loss (Without Connectors)
1.0 dB (Typ.)
1.2 dB (Max)
Polarization Dependent Loss (PDL)
≤0.25 dB
Return Loss
≥50 dB
a) The maximum power specification represents the maximum power for the combined forward and
reverse directions. Therefore, the sum of the powers in the forward and reverse directions cannot
exceed the maximum power specification.

850 nm Fiber Isolator Chapter 7: Drawing
Rev B, Sept. 14, 2018 Page 7
Chapter 7 Drawing

850 nm Fiber Isolator Chapter 8: Regulatory
Page 8 17189-D02
Chapter 8 Regulatory
As required by the WEEE (Waste Electrical and Electronic Equipment Directive)
of the European Community and the corresponding national laws, Thorlabs offers
all end users in the EC the possibility to return “end of life” units without incurring
disposal charges.
This offer is valid for Thorlabs electrical and electronic equipment:
Sold after August 13, 2005
Marked correspondingly with the crossed out
“wheelie bin” logo (see right)
Sold to a company or institute within the EC
Currently owned by a company or institute
within the EC
Still complete, not disassembled and not
contaminated
As the WEEE directive applies to self-contained
operational electrical and electronic products, this end of
life take back service does not refer to other Thorlabs products, such as:
Pure OEM products, that means assemblies to be built into a unit by the
user (e.g. OEM laser driver cards)
Components
Mechanics and optics
Left over parts of units disassembled by the user (PCB’s, housings etc.).
If you wish to return a Thorlabs unit for waste recovery, please contact Thorlabs
or your nearest dealer for further information.
8.1. Waste Treatment is Your Own Responsibility
If you do not return an “end of life” unit to Thorlabs, you must hand it to a
company specialized in waste recovery. Do not dispose of the unit in a litter bin
or at a public waste disposal site.
8.2. Ecological Background
It is well known that WEEE pollutes the environment by releasing toxic products
during decomposition. The aim of the European RoHS directive is to reduce the
content of toxic substances in electronic products in the future.
The intent of the WEEE directive is to enforce the recycling of WEEE. A
controlled recycling of end of life products will thereby avoid negative impacts on
the environment.
Wheelie Bin Logo