UV Free-Space Isolators


UV Free-Space Isolators (365 - 385 nm)

  • Center Wavelength of 375 nm
  • Isolation up to 30dB
  • 100 W/cm2 Power Density
  • Custom Isolators Also Available


  • Minimize Feedback into Optical Systems
  • Free-Space Input and Output Ports
  • Tunable Wavelength Ranges
  • 30 dB Peak Isolation
  • Ø3.0 mm or Ø5.0 mm Input Aperture (Model Dependent)
  • Polarization-Dependent Input
  • Custom Isolators Available 

Thorlabs is pleased to stock these free-space optical isolators, which have been designed for use in the UV spectral range (365 - 385 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.

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

In the UV wavelength range, we offer adjustable narrowband isolators. These offer the user the ability to adjust the alignment of the input and output polarizers, allowing tuning of the center wavelength within a 10 nm range and an operation range of 20 nm. 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 into the infrared (see the Selection Guide table to the left). If Thorlabs does not stock an isolator suited for your application, please refer to our Custom Isolators page 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).


375 nm Polarization-Dependent Isolators


Click Image for Details
Item # IO-3-375-GLBa IO-5-375-GLBb
Type Adjustable Narrowband Adjustable Narrowband
Center Wavelength 375 nm 375 nm
Tuning Range 370 - 380 nm 370 - 380 nm
Operating Range 365 - 385 nm 365 - 385 nm
Transmissionc 70% 70%
Isolationc 30 dB 30 dB
Performance Graph
(Click for Details)
Max Beam Diameterd 2.7 mm 4.7 mm
Max Power 3 W 8 W
Max Power Density 100 W/cm2 100 W/cm2


  • The mounting saddle contains one 8-32 and two 1/4"-20 taps.
  • The housing of this isolator cannot be freely rotated in its saddle. However, tapped holes in the housing allow the isolator to be mounted with the polarization axis either parallel or perpendicular to the base of the mount.
  • Specified at center wavelength. See Performance Graph for wavelength dependence.
  • Defined as containing 100% of the beam energy.



Isolator Mounting Adapters

These adapters provide mechanical compatibility between our isolator bodies and SM2 (2.035"-40) lens tubes, SM3 (3.035"-40) lens tubes, 30 mm cage systems, or Ø1/2" posts.


Click Image to Enlarge
Item # CP12 SM1RC(/M) SM1TC SM2A21 SM3B2
Isolator Diameter 1.2" 1.2" 1.2" 1.2" 2.0"
Mounting Options 30 mm Cage Systems Ø1/2" Posts Ø1/2" Posts SM2 Lens Tubes or Mechanics with Ø2" Bore SM3 Lens Tubes
Compatible Isolators IO-3-375-GLB IO-5-375-GLB


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