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MIR Free-Space Isolators (3.35 - 4.55 µm)


  • Center Wavelength: 3.4 µm or 4.5 µm
  • Minimum Isolation of 30 dB
  • Maximum Beam Size of Ø3.6 mm
  • Custom Isolators Available Upon Request

IO-4-4500-WG

In Saddle

IO-4-4500-WG

Shown in the Included Saddle (SM05RC),
Mounted on an Optical Table Using a
BA1 Base and SD1 1/4" Counterbore
Adapter Ring for 8-32 Cap Screws

IO-4-3400-WG

Removed 
from Saddle

Related Items


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Tunable Isolation Curve
Click to Enlarge

Our Adjustable Narrowband Isolators can be tuned to maximize the peak isolation for any wavelength within a narrow spectral range (shaded in this graph). See the Wavelength Tuning tab for more details.
Custom Isolators
  • Customizable Wavelength, Aperture, Max Power, Housing, Polarizers, and Operating Temperature
  • Pricing Similar to Stock Units
  • Wide Range of OEM Capabilities
  • Please Contact Tech Support or See Our Custom Isolators Page

Features

  • Minimize Feedback into Optical Systems
  • Free-Space Input and Output Ports
  • Minimum Isolation at Center Wavelength of 30 dB
  • Tunable Center Wavelength
  • Ø3.6 mm Max Beam
  • Polarization-Dependent Input

These free-space optical isolators are designed for use in the MIR spectral range (3.35 - 3.45 µm or 4.45 - 4.55 µm). Optical isolators, also known as Faraday isolators, are magneto-optic devices that preferentially transmit light along a single direction, shielding upstream optics from back reflections. Back reflections can create a number of instabilities in light sources, including intensity noise, frequency shifts, mode hopping, and loss of mode lock. In addition, intense back-reflected light can permanently damage optics. Please see the Isolator Tutorial tab for an explanation of the operating principles of a Faraday isolator.

Selection Guide for Isolators
(Click Here for Our Full Selection)
Free-Space Isolators
Spectral Region Wavelength Range
UV 365 - 385 nm
Visible 390 - 700 nm
NIR 690 - 1080 nm
Nd:YAG 1064 nm
IR 1110 - 2100 nm
MIR 3.35 - 4.55 µm
Broadband Free-Space Isolators
Fiber Isolators
Custom Isolators

Thorlabs' Adjustable Narrowband MIR Isolators are factory aligned to provide peak isolation at the specified center wavelength. They also offer the user the ability to adjust the alignment of the output polarizer with respect to the input polarizer, allowing the peak of the isolation curve to lie anywhere within a 50 - 100 nm range; see the tables below for details. Please see the Isolator Types tab for additional design details and representative graphs of the wavelength-dependent isolation.

Each isolator's housing is marked with an arrow that indicates the direction of forward propagation. In addition, all isolators have engravings that indicate the alignment of the input and output polarizers.

Thorlabs also manufactures isolators for fiber optic systems and wavelengths extending down to the UV (see the Selection Guide table to the left). If Thorlabs does not stock an isolator suited for your application, please refer to the Custom Isolators tab for information on our build-to-order options, or contact Tech Support. Thorlabs' in-house manufacturing service has over 25 years of experience and can deliver a free-space isolator tuned to your center wavelength from 244 nm to 4.55 µm.

The shaded region on each graph below represents the wavelength tuning range of the isolator. The peaks of the isolation and transmission curves can be shifted anywhere within this range by rotating the output polarizer, as detailed in the Wavelength Tuning tab. These curves show theoretical data; isolation and transmission will vary from unit to unit.

Tuning an Adjustable Narrowband Isolator

  • Optimize Our Isolators to Provide the Same Peak Isolation Anywhere Within Their Tuning Range
  • Simple Tuning Procedure, Illustrated Below, Consists Primarily of Rotating the Output Polarizer
  • Slight Transmission Losses Occur Due to Polarizer Rotation
Dependence of Transmission on Center Wavelength
Click to Enlarge

When the isolator is tuned away from its design wavelength, the maximum transmission falls because the output polarizer's transmission axis is not parallel to the polarization direction of the output light.
Tunable Isolation Curves
Click to Enlarge

Our Adjustable Narrowband Isolators can be tuned to maximize the peak isolation for any wavelength within a narrow spectral range (shaded in this graph).


Click to Enlarge

Light Not at the Design Wavelength is Partially Transmitted

Click to Enlarge

Light at the Design Wavelength is Rejected

Operating Principles of Optical Isolators
Thorlabs' Adjustable Narrowband Isolators are designed to provide the same peak isolation anywhere within a 50 - 100 nm tuning range. They contain a Faraday rotator that has been factory tuned to rotate light of the design wavelength by 45°. Light propagating through the isolator in the backward direction is polarized at 45° by the output polarizer and is rotated by 45° by the Faraday rotator, giving a net polarization of 90° relative to the transmission axis of the input polarizer. Therefore, an isolator rejects backward propagating light. See the Isolator Tutorial tab for a schematic of the beam path.

The magnitude of the rotation caused by the Faraday rotator is wavelength dependent. This means that light with a different wavelength than the design wavelength will not be rotated at exactly 45°. For example, if 4.5 µm light is rotated by 45° (that is, 4.5 µm is the design wavelength), then 4.45 µm light is rotated by 45.4°. If 4.45 µm light is sent backward through an isolator designed for 4.5 µm without any tweaking, it will have a net polarization of 45° + 45.4° = 90.4° relative to the axis of the input polarizer. The polarization component of the light parallel to the input polarizer's axis will be transmitted, and the isolation will therefore be reduced.

Since the net polarization needs to be 90° to obtain the maximum isolation, the output polarizer is rotated to compensate for the extra rotation being caused by the Faraday isolator. In our example, the new polarizer angle is 90° - 45.4° = 44.6°. This adjustment increases the isolation back to the same value as at the design wavelength.

Consequences of Wavelength Tuning Procedure
As a direct consequence of rotating the output polarizer, the maximum transmission in the forward direction decreases. 4.45 µm light propagating in the forward direction is polarized at 0° by the input polarizer and rotated by 45.4° by the Faraday rotator, but the output polarizer is now at 44.6°. The amount of the transmission decrease can be quantified using Malus' Law:

Malus's Law
Malus' Law

Here, θ is the angle between the polarization direction of the light after the Faraday rotator and the transmission axis of the polarizer, I0 is the incident intensity, and I is the transmitted intensity. The decrease in transmission is very slight for our mid-IR isolators. In our example (a 50 nm difference between the design wavelength and the usage wavelength), θ = 45.4° - 44.6° = 0.8°, so I = 0.9998 I0. This case is shown in the graphs above.

Thorlabs' isolator housings make it easy to rotate the output polarizer without disturbing the rest of the isolator. Our custom isolator manufacturing service (see the Custom Isolators tab) can also provide an isolator specifically designed for a particular center wavelength. These custom isolators are provided at the same cost as their equivalent stock counterparts. For more information, please contact Technical Support.


Illustrated Tuning Procedure

To optimize the isolation curve for a specific wavelength within the tuning range, the alignment of the output polarizer may be tweaked following the simple procedure outlined below. Only a minor adjustment is necessary to cover a range of tens of nanometers. The procedure differs slightly for different isolator packages, but the principle remains the same across our entire isolator family, and complete model-specific tuning instructions ship with each isolator.

Step 1:
Orient the isolator in the backward direction with respect to the beam (i.e., with the arrow pointing antiparallel to the beam propagation direction). A power meter with high sensitivity at low power levels should be placed after the isolator.

Use the included 5/64" hex key to loosen the isolator from its saddle.

Step 2:
Grip the isolator by the sides and gently bring it out of its saddle. It is only necessary to bring it out far enough to expose the 8-32 setscrew at the top, as shown in the photo to the left.

Step 3:
Use the included 5/64" hex key to tighten the isolator back into its saddle with the 8-32 setscrew exposed.

The isolator is mechanically stable in this position as long as the isolator has not been brought forward too much. (The amount shown in the image to the left is safe by several millimeters.) It should therefore not be necessary to reinsert the isolator at the end of the tuning procedure.

Step 4:
Loosen the exposed 8-32 setscrew using the included 5/64" hex key. At this point, the output polarizer will be free to rotate.

Step 5:
Rotate the output polarizer to minimize the power on the power meter. As explained above, the necessary adjustment should be less than 1°. Tighten the 8-32 setscrew once optimization is achieved.

As long as the isolator was not brought forward too much at the end of Step 2, the isolator will be mechanically stable in this position. Attempting to reinsert the isolator at this point may cause misalignment.

Fixed Narrowband Isolation

Fixed Narrowband Isolator

The isolator is set for 45° of rotation at the design wavelength. The polarizers are non-adjustable and are set to provide maximum isolation at the design wavelength. As the wavelength changes the isolation will drop; the graph shows a representative profile.

  • Fixed Rotator Element, Fixed Polarizers
  • Polarization Dependent
  • Smallest and Least Expensive Isolator Type
  • No Tuning

Adjustable Narrowband Isolation

Adjustable Narrowband Isolator

The isolator is set for 45° of rotation at the design wavelength. If the usage wavelength changes, the Faraday rotation will change, thereby decreasing the isolation. To regain maximum isolation, the output polarizer can be rotated to "re-center" the isolation curve. This rotation causes transmission losses in the forward direction that increase as the difference between the usage wavelength and the design wavelength grows.

  • Fixed Rotator Element, Adjustable Polarizers
  • Polarization Dependent
  • General-Purpose Isolator

Adjustable Broadband Isolation

Adjustable Broadband Isolator

The isolator is set for 45° of rotation at the design wavelength. There is a tuning ring on the isolator that adjusts the amount of Faraday rotator material that is inserted into the internal magnet. As your usage wavelength changes, the Faraday rotation will change, thereby decreasing the isolation. To regain maximum isolation, the tuning ring is adjusted to produce the 45° of rotation necessary for maximum isolation.

  • Adjustable Rotator Element, Fixed Polarizers
  • Polarization Dependent
  • Simple Tuning Procedure
  • Broader Tuning Range than Adjustable Narrowband Isolators

Fixed Broadband

Fixed Broadband Isolator

A 45° Faraday rotator is coupled with a 45° crystal quartz rotator to produce a combined 90° rotation on the output.  The wavelength dependences of the two rotator materials work together to produce a flat-top isolation profile. The isolator does not require any tuning or adjustment for operation within the designated design bandwidth.

  • Fixed Rotator Element, Fixed Polarizers
  • Polarization Dependent
  • Largest Isolation Bandwidth
  • No Tuning Required

Tandem Isolators

Tandem Isolators

Tandem isolators consist of two Faraday rotators in series, which share one central polarizer. Since the two rotators cancel each other, the net rotation at the output is 0°. Our tandem designs yield narrowband isolators that may be fixed or adjustable.

  • Up to 60 dB Isolation
  • Polarization Dependent
  • Highest Isolation
  • Fixed or Adjustable

Polarizer Types, Sizes, and Power Limits

Thorlabs designs and manufactures several types of polarizers that are used across our family of optical isolators. Their design characteristics are detailed below. The suffix of the part number of a given isolator identifies the type of polarizer that isolator contains.

Polarizer Comparison
Type Schematic
(Click to Enlarge)
Maximum Power Density Description
Very Low Power
(VLP)
VLP Polarizer 25 W/cm2 (CW, Blocking)
100 W/cm2 (CW, Transmission)
Our Very Low Power Absorptive Film Polarizers are the most compact option. For light polarized perpendicular to the polarizer's transmission axis, the max power density is 25 W/cm2, while for light polarized parallel to the polarizer's transmission axis, the max power density is 100 W/cm2.
Wire Grid
(WG)
VLP Polarizer 25 W/cm2 (CW) Wire Grid Polarizers are used in our mid-IR isolators. They consist of a linearly spaced wire grid pattern that is deposited onto an AR-coated silicon substrate.
Polarizing Beamsplitter
(PBS)
PBS Polarizer 13 - 50 W/cm2 (CW) Polarizing Beamsplitter Cubes are commonly used in low-power applications and feature an escape window useful for monitoring or injection locking.
α-BBO
Glan-Laser
(GLB)
GLB Polarizer 100 W/cm2 (CW) Thorlabs' α-BBO Glan-Laser polarizers are all based on high-grade, birefringent, α-BBO crystals with a wavelength range of 210 - 450 nm. Due to the birefringent structure of α-BBO, a phase delay is created between two orthogonally polarized waves traveling in the crystal. These are similar to the High Power (HP) polarizers, but have a different escape angle.
Low Power
(LP)
LP Polarizer 250 W/cm2 (CW)
25 MW/cm2 (Pulsed)
Our Low Power Polarizers are Glan-type, crystal polarizers, providing high transmission and power densities at the expense of a larger package than Very Low Power (VLP) and Polarizing Beamsplitter (PBS) polarizers.
Medium Power
(MP)
MP Polarizer 100 W/cm2 (CW)
50 MW/cm2 (Pulsed)
Medium Power Polarizers are Glan-type, crystal polarizers, capable of handling higher powers. The rejected beam is internally scattered, which reduces the maximum power density, but also eliminates a stray beam from the setup.
High Power
(HP)
HP Polarizer 500 W/cm2 (CW)
150 MW/cm2 (Pulsed)
High Power Polarizers are Glan-type, crystal polarizers, similar in size and transmission to Medium Power (MP) polarizers, but capable of handling higher powers. They feature an escape window suited for injection locking.
Very High Power
(VHP)
VHP Polarizer 20 kW/cm2 (CW)
2 GW/cm2 (Pulsed)
Our Very High Power Polarizers are based on Brewster windows and feature the highest power handling possible. These polarizers have larger packages than HP-based designs, but are also more economical. All VHP-based designs also feature escape windows.

Optical Isolator Tutorial

Function
An optical isolator is a passive magneto-optic device that only allows light to travel in one direction. Isolators are used to protect a source from back reflections or signals that may occur after the isolator. Back reflections can damage a laser source or cause it to mode hop, amplitude modulate, or frequency shift. In high-power applications, back reflections can cause instabilities and power spikes.

An isolator's function is based on the Faraday Effect. In 1842, Michael Faraday discovered that the plane of polarized light rotates while transmitting through glass (or other materials) that is exposed to a magnetic field. The direction of rotation is dependent on the direction of the magnetic field and not on the direction of light propagation; thus, the rotation is non-reciprocal. The amount of rotation Q equals V x L x H, where V, L, and H are as defined below.

 

Faraday Effect in an Isolator Drawing
Figure 1. Faraday Rotator's Effect on Linearly Polarized Light

Faraday Rotation

Q = V x L x H

V: the Verdet Constant, a property of the optical material, in minutes/Oersted-cm.

L: the path length through the optical material in cm.

H: the magnetic field strength in Oersted.

An optical isolator consists of an input polarizer, a Faraday rotator with magnet, and an output polarizer. The input polarizer works as a filter to allow only linearly polarized light into the Faraday rotator. The Faraday element rotates the input light's polarization by 45°, after which it exits through another linear polarizer. The output light is now rotated by 45° with respect to the input signal. In the reverse direction, the Faraday rotator continues to rotate the light's polarization in the same direction that it did in the forward direction so that the polarization of the light is now rotated 90° with respect to the input signal. This light's polarization is now perpendicular to the transmission axis of the input polarizer, and as a result, the energy is either reflected or absorbed depending on the type of polarizer.

 

Drawing of Light Propagation Through an Isolator
Figure 2. A polarization-dependent isolator. Light propagating in the reverse direction is rejected by the input polarizer.

Polarization-Dependent Isolators

The Forward Mode
In this example, we will assume that the input polarizer's axis is vertical (0° in Figure 2). Laser light, either polarized or unpolarized, enters the input polarizer and becomes vertically polarized. The Faraday rotator will rotate the plane of polarization (POP) by 45° in the positive direction. Finally, the light exits through the output polarizer which has its axis at 45°. Therefore, the light leaves the isolator with a POP of 45°.

The Reverse Mode
Light traveling backwards through the isolator will first enter the output polarizer, which polarizes the light at 45° with respect to the input polarizer. It then passes through the Faraday rotator rod, and the POP is rotated another 45° in the positive direction. This results in a net rotation of 90° with respect to the input polarizer, and thus, the POP is now perpendicular to the transmission axis of the input polarizer. Hence, the light will either be reflected or absorbed.

 

Light Propagation Through a Polarization-Independent IsolatorClick for Details
Figure 3. A polarization independent isolator. Light is deflected away from the input path and stopped by the housing.

Polarization-Independent Fiber Isolators

The Forward Mode
In a polarization independent fiber isolator, the incoming light is split into two branches by a birefringent crystal (see Figure 3). A Faraday rotator and a half-wave plate rotate the polarization of each branch before they encounter a second birefringent crystal aligned to recombine the two beams.

The Reverse Mode
Back-reflected light will encounter the second birefringent crystal and be split into two beams with their polarizations aligned with the forward mode light. The faraday rotator is a non-reciprocal rotator, so it will cancel out the rotation introduced by the half wave plate for the reverse mode light. When the light encounters the input birefringent beam displacer, it will be deflected away from the collimating lens and into the walls of the isolator housing, preventing the reverse mode from entering the input fiber.

 

General Information

Damage Threshold
With 25 years of experience and 5 U.S. patents, our isolators typically have higher transmission and isolation than other isolators, and are smaller than other units of equivalent aperture. For visible to YAG laser Isolators, Thorlabs' Faraday Rotator crystal of choice is TGG (terbium-gallium-garnet), which is unsurpassed in terms of optical quality, Verdet constant, and resistance to high laser power. Thorlabs' TGG Isolator rods have been damage tested to 22.5 J/cm2 at 1064 nm in 15 ns pulses (1.5 GW/cm2), and to 20 kW/cm2 CW. However, Thorlabs does not bear responsibility for laser power damage that is attributed to hot spots in the beam.

Dispersion Measurement of Isolator IO-5-780-HP
Figure 4. Pulse Dispersion Measurements Before and After an IO-5-780-HP Isolator

Magnet
The magnet is a major factor in determining the size and performance of an isolator. The ultimate size of the magnet is not simply determined by magnetic field strength but is also influenced by the mechanical design. Many Thorlabs magnets are not simple one piece magnets but are complex assemblies. Thorlabs' modeling systems allow optimization of the many parameters that affect size, optical path length, total rotation, and field uniformity. Thorlabs' US Patent 4,856,878 describes one such design that is used in several of the larger aperture isolators for YAG lasers. Thorlabs emphasizes that a powerful magnetic field exists around these Isolators, and thus, steel or magnetic objects should not be brought closer than 5 cm.

Temperature
The magnets and the Faraday rotator materials both exhibit a temperature dependence. Both the magnetic field strength and the Verdet Constant decrease with increased temperature. For operation greater than ±10 °C beyond room temperature, please contact Technical Support.

Pulse Dispersion
Pulse broadening occurs anytime a pulse propagates through a material with an index of refraction greater than 1. This dispersion increases inversely with the pulse width and therefore can become significant in ultrafast lasers.

τ: Pulse Width Before Isolator

τ(z): Pulse Width After Isolator

Example:
t = 197 fs results in t(z) = 306 fs (pictured to the right)
t = 120 fs results in t(z) = 186 fs

Optical Isolator in FiberBench Mount
Click to Enlarge

Custom Isolator Example
Custom Adjustable Narrowband Isolator with Different Input and Output Polarizers Optimized for 650 nm Wavelength and 40 °C Temperature.
OEM Application Services
  • Direct Integration to Laser Head Assemblies
  • Combination Isolator and Fiber Coupling Units
  • Minimum Footprint Packages
  • Filter Integration
  • Active Temperature Control and Monitoring
  • Feedback Monitoring
  • Environmental Qualification
  • Private Labeling
  • ITAR-Compliant Assembly

OEM and Non-Standard Isolators

In an effort to provide the best possible service to our customers, Thorlabs has made a commitment to ship our most popular free-space and fiber isolator models from stock. We currently offer same-day shipping on more than 90 isolator models. In addition to these stock models, non-stock isolators with differing aperture sizes, wavelength ranges, package sizes, and polarizers are available. In addition, we can create isolators tuned for specific operating temperatures and isolators that incorporate thermistors with heating or cooling elements for active temperature control and monitoring. These generally have the same price as a similar stock unit. If you would like a quote on a non-stock isolator, please fill out the form below and a member of our staff will be in contact with you.

Thorlabs has many years of experience working with OEM, government, and research customers, allowing us to tailor your isolator to specific design requirements. In addition to customizing our isolators (see the OEM Application Services list to the right), we also offer various application services.

 

Parameter Range
Wavelength Range From 244 - 4550 nma
Aperture Sizes  Up to Ø15 mm
Polarization Dependence Dependent or Independent
Max Powerb Up to 2 GW/cm²
Isolation Up to 60 dB (Tandem Units)
Operating Temperature 10 - 70 °C
  • Custom Faraday rotators, for use in the 244 to 5000 nm range, are also available.
  • 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.

Free-Space Isolators

We are able to provide a wide range of flexibility in manufacturing non-stock, free-space isolators. Almost any selection of specifications from our standard product line can be combined to suit a particular need. The table to the right shows the range of specifications that we can meet.

We offer isolators suitable for both narrowband and broadband applications. The size of the housing is very dependent on the desired maximum power and aperture size, so please include a note in the quote form below if you have special requirements.

 

Faraday Rotators

We can also offer Faraday rotators which rotate the polarization of incoming light by 45° ± 3°. These are similar to our isolators but with the polarizers at each end removed. They are available with center wavelengths from 244 to 5000 nm.

 

Parameter Range
Wavelength Range From 633 - 2050 nma
Polarization Dependence Dependent or Independent
Max Powerb (Fiber to Free-Space) 30 W
Max Powerb (Fiber to Fiber) 20 W
Operating Temperature 10 - 70 °C
  • For wavelengths shorter than 633 nm, we recommend using our free-space isolators in conjunction with our modular FiberBench accessories. Please contact Technical Support for more information.
  • 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.

Fiber Isolators

Thorlabs is uniquely positioned to draw on experience in classical optics, fiber coupling, and isolators to provide flexible designs for a wide range of fiber optic specifications. Current design efforts are focused on increasing the Maximum power of our fiber isolators at and near the 1064 nm wavelength. We offer models with integrated ASE filters and taps. The table to the right highlights the range of specifications that we can meet.

The fiber used is often the limiting factor in determining the Maximum power the isolator can handle. We have experience working with single mode (SM) and polarization-maintaining fibers (PM); single-, double- and triple-clad fibers; and specialty fibers like 10-to-30 µm LMA fibers and PM LMA fibers. For more information about the fiber options available with our custom isolators, please see the expandable tables below.

In the spectral region below 633 nm, we recommend mounting one of our free-space isolators in a FiberBench system. A FiberBench system consists of pre-designed modules that make it easy to use free-space optical elements with a fiber optic system while maintaining excellent coupling efficiency. Upon request, we can provide select stock isolators in an optic mount with twin steel dowel pins for our FiberBench systems, as shown to the left.

We are also in the process of extending our fiber isolator capabilities down into the visible region. For more information, please contact Technical Support.

Custom Fiber Isolator
Custom Free-Space Isolator for Wavelengths Below 633 nm
Optical Isolator in FiberBench Mount
Click to Enlarge

Twin Steel Pins Insert into FiberBench
Optical Isolator in FiberBench Mount
Click to Enlarge

Mounted Isolator
Polarization Independent Fiber
Polarization Maintaining Fiber

 

Make to Order Options

The expandable tables below provide information on some common isolator and rotator specials we have manufactured in the past. We keep the majority of the components for these custom isolators in stock to ensure quick builds, so these specials are available with an average lead time of only 2-4 weeks.  Please use the Non-Stock Isolator Worksheet below for a quote.

Adjustable Narrowband Isolators
Faraday Rotators
Fixed Narrowband Isolators
Fixed Broadband Isolators

 

Custom Request Form

Request a custom isolator quote using the form below or by contacting us for more information at (973) 300-3000.

Non-Stock Isolator Worksheet:
Please select your input type:   Free-Space Input  |    Fiber Input
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Free-Space Input
Wavelength or Wavelength Range (nm):
Power (W):
Max 1/e2 Beam Diameter (mm):
Isolation (dB):
% Transmission:
Notes:
Fiber Input
Wavelength or Wavelength Range (nm):
Power (W):
Polarization Sensitivity:  Dependent   |     Indepentent
Isolation (dB):
% Transmission:
Fiber:
Fiber Connector:   FC/PC   |     FC/APC   |     Other
Output:   Fiber   |     Free-Space
Notes:

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Posted Comments:
Poster:r.woodward12
Posted Date:2016-10-25 03:29:00.587
Please could you give an indication of price and lead time for custom isolators? I'm specifically interested in a free space product for use at 4 um (or even better, one with tunability from 3 to 5 um). I tried to use the online form, but this did not work on my mobile (Android) as I was unable to swipe the security feature to show the submit button! Additionally, which formula is used to ppredict performance with respect to wavelength in the displayed graphs please? I'd be interested to know how the 4.5 um off-the-shelf isolator performs at 4 um, for example. If any further information is required, please don't hesitate to contact me. Best wishes Robert Woodward
Poster:tfrisch
Posted Date:2016-10-25 11:57:21.0
Hello, thank you for contacting Thorlabs. I have contacted you directly about these inquiries.

The following selection guide contains all of Thorlabs' Free-Space Optical Isolators. Click the colored bars below to to see specifications and options for each wavelength range and isolator type. Please note that Thorlabs also offers fiber optical isolators and custom optical isolators.

Optical_Isolator

3.4 µm Polarization-Dependent Isolator

Click Image for Details
Item # IO-4-3400-WG
Type Adjustable Narrowband
Center Wavelength 3.4 µm
Tuning Range 3.375 - 3.425 µm
Operating Range 3.350 - 3.450 µm
Transmissiona 80%
Isolationa 30 dB (Min)
Performance Graph
(Click for Details)
Click for Details
Max Beam Diameterb 3.6 mm
Max Powerc 1.2 W 
Max Power Density 25 W/cm2
Compatible Mounting Adapterse FBS05
SM05RCf (SM05RC/M)
SM05TC
  • Specified at center wavelength. See Performance Graph for wavelength dependence.
  • Defined as containing 100% of the beam energy.
  • 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.
  • The blocking power density corresponds to light polarized perpendicular to the transmission axis, while the transmission power density corresponds to light polarized parallel to the transmission axis.
  • Please see below for further details.
  • One SM05RC with an 8-32 tap is included with this isolator. For an SM05RC/M with an M4 tap, please contact Tech Support prior to ordering.
Mechanical Drawing
IO-4-3400-WG Mechanical Drawing
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
IO-4-3400-WG Support Documentation
IO-4-3400-WGFree-Space Isolator, 3.4 µm, 3.6 mm Max Beam, 1.2 W Max
$2,454.00
Today

4.5 µm Polarization-Dependent Isolator

Click Image for Details IO-4-4500-WG
Item # IO-4-4500-WG
Type Adjustable Narrowband
Center Wavelength 4.5 µm
Tuning Range 4.45 - 4.55 µm
Operating Range 4.45 - 4.55 µm
Transmissiona 75%
Isolationa 30 dB (Min)
Performance Graph
(Click for Details)
Click for Details
Max Beam Diameterb 3.6 mm
Max Powerc 1 W 
Max Power Density 25 W/cm2
Compatible Mounting Adaptersd FBS05
SM05RCf (SM05RC/M)
SM05TC
  • Specified at center wavelength. See Performance Graph for wavelength dependence.
  • Defined as containing 100% of the beam energy.
  • 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.
  • Please see below for further details.
  • One SM05RC with an 8-32 tap is included with this isolator. For an SM05RC/M with an M4 tap, please contact Tech Support prior to ordering.
Mechanical Drawing
IO-4-4500-WG Mechanical Drawing
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
IO-4-4500-WG Support Documentation
IO-4-4500-WGCustomer Inspired!Free-Space Isolator, 4.5 µm, 3.6 mm Max Beam, 1 W Max
$4,039.00
Today

Isolator Mounting Adapters

These adapters provide mechanical compatibility between our isolator bodies and Ø1/2" posts or FiberBench systems.

Click Image to Enlarge FBS05 SM05RC SM05TC
Item # FBS05 SM05RC(/M) SM05TC
Isolator Diameter 0.70" 0.70" 0.70"
Mounting Options FiberBench Systems Ø1/2" Posts Ø1/2" Posts
Compatible Isolators IO-4-3400-WG
IO-4-4500-WG
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available / Ships
SM05RC Support Documentation
SM05RCØ0.70" Slip Ring for SM05 Lens Tubes, 8-32 Tap
$19.70
3-5 Days
+1 Qty Docs Part Number - Universal Price Available / Ships
FBS05 Support Documentation
FBS05FiberBench Ø1/2" Lens Tube Mount
$47.00
Today
SM05TC Support Documentation
SM05TCØ0.70" Clamp for SM05 Lens Tubes
$39.00
Today
+1 Qty Docs Part Number - Metric Price Available / Ships
SM05RC/M Support Documentation
SM05RC/MØ0.70" Slip Ring for SM05 Lens Tubes, M4 Tap
$19.70
Today
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