Broadband Free-Space Isolators


Broadband Free-Space Isolators (650 - 1000 nm)

  • Operating ranges as Broad as 330 nm
  • Fixed or Tunable Center Wavelength
  • Isolation up to 40dB
  • Power up to 40 W


  • Minimize Feedback into Optical Systems
  • Free-Space Input and Output Ports
  • Fixed or Tunable Wavelength Ranges
  • At Least 30 dB Isolation Over a Broad Spectral Range
  • Peak Isolation of 40 dB
  • Ø4.5 mm Apertures
  • Polarization-Dependent Input
  • Custom Isolators Available 

Thorlabs is pleased to stock a variety of free-space optical isolators designed for broadband applications in the near infrared spectral range (650 - 1000 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.

For broadband applications in the near infrared range, we offer two types of isolators. The first type, Adjustable Broadband Isolators, offers the user the ability to adjust the alignment of the input and output polarizers, allowing tuning of the center wavelength over a range greater than 200 nm and operating ranges as broad as 330 nm. The second type, Fixed Broadband Isolators (IO-5BB-800-HP), offers a nearly flat isolation of 30 dB in the 748 - 851 nm wavelength range, helping to preserve the temporal profile of the input pulse.

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 from the visible to the infrared (see the Selection Guide table to the right). 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
Broadband Free-Space Isolators


Broadband NIR Polarization-Dependent Isolators

Item # IO-5-NIR-LP IO-5BB-800-HPa IO-5-TIS2-HP
Type Adjustable Broadband Fixed Broadband Adjustable Broadband
Center Wavelength N/A 800 nm N/A
Tuning Range 700 - 925 nm N/A 780 - 1000 nm
Operating Range 650 - 980 nm 748 - 851 nm 780 - 1000 nm
Transmission 93% 88% 91%
Isolation 36 - 40 dB 30 dB 33 - 39 dB
Performance Graph
Max Beam Diameterb 4.5 mm 4.5 mm 4.5 mm
Max Power 7 W 35 W 40 W
Max Power Density 250 W/cm2 500 W/cm2 500 W/cm2
  • The mounting saddle contains one 8-32 and two 1/4"-20 taps.
  • Defined as containing 100% of the beam energy.



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