IR Free-Space Isolators


IR Free-Space Isolators (1120 - 2100 nm)

  • Isolation up to 60dB
  • Power Densities up to 250 W/cm2
  • Custom Isolators Available With up to 2.8 um Center Wavelength


  • Eight Center Wavelength Options: 1150, 1220, 1310, 1390, 1480, 1550, 1650, or 2050 nm
  • Fixed or Tunable Wavelength Ranges
  • Free-Space Input and Output Ports
  • Peak Isolation from 28 to 60 dB
  • Apertures up to Ø4.7 mm
  • Polarization-Dependent Input
  • Custom Isolators Available 

Thorlabs is pleased to stock a variety of free-space optical isolators designed for use in the infrared spectral range (1120 - 2100 nm). 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.

In the infrared wavelength range, we offer three types of isolators. The first type, Fixed Narrowband Isolators, contains fixed, factory-aligned optics, for which peak isolation and peak transmission occurs at a pre-defined center wavelength. Any deviation from this wavelength will cause a dip in isolation and transmission. The second type, Adjustable Narrowband Isolators, offers the user the ability to adjust the alignment of the input and output polarizers, allowing tuning of the center wavelength within a 60 - 100 nm range, depending upon the exact isolator. The third type, Tandem Fixed Narrowband Isolators (IOT-4-1550-VLP), consists of two Faraday rotators in series, boosting the isolation to 60 dB at the expense of lower transmission. 

Except for the IO-D-1550-VLP, the housing of each isolator shown here is marked with an arrow that indicates the direction of forward propagation. All isolators shown here (including the IO-D-1550-VLP) have engravings that indicate the alignment of the input and output polarizers.

Thorlabs also manufactures isolators for fiber optic systems and wavelengths down into the visible . As indicated in the tables below and pictured to the right, many of our stock isolators can also be provided in a mount designed for our FiberBench systems. If Thorlabs does not stock an isolator suited for your application, please refer to the Non-Stock 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 - 2800 nm).

Selection Guide for Isolators
Free-Space Isolators
Spectral Region Wavelength Range
UV 365 - 385 nm
Visible 395 - 690 nm
NIR 760 - 1050 nm
Nd:YAG 1064 nm
IR 1120 - 2100 nm


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