Visible Fiber Isolator (SM Fiber)


Visible Fiber Optic Isolators with SM Fiber (650 - 670 nm)

  • Center Wavelength at 660 nm
  • Isolation ≥25 dB
  • Unconnectorized SM Fiber
  • OEM and Build-to-Order Fiber Isolators Available


  • Minimize Feedback into Optical Systems
  • Operating Range of 650 - 670 nm
  • At Least 1.0 m of Unconnectorized SM Fiber on Both Sides
  • Designed for CW Applications
  • Each Unit is Individually Tested
  • Custom Isolators Available 

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 .

Isolator Schematic A polarization independent isolator. Light is deflected away from the input path and stopped by the housing.

Thorlabs' polarization-independent visible isolator, sold on this page, is compatible with single mode (SM) fibers. A length of 1.0 m of fiber is built in to each side of the isolator, and an arrow on the body indicates 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.

To achieve the specified return loss for this isolator, we recommend mechanically splicing these isolators into your optical system. The dimensional tolerance of fiber connectors will typically cause a slight misalingment of the fiber cores at the connection point. Fibers with shorter operating wavelengths, such as the SM600 fiber used in this isolator, have smaller core sizes, causing this misalignment to result in significant coupling losses. Connectorizing this isolator will also lower the maximum power that the isolator can handle. The small core size will result in an extremely high energy density at the connector's air-to-glass interface, which may result in damage to the connector and the fiber tip.


660 nm Polarization-Independent Isolator

IO-F-660 Simplified Mechanical Drawing


Item # IO-F-660
Polarization Independent
Fiber Type SM
Center Wavelength 660 nm
Operating Range 650 - 670 nm
Max Powera 0.5 W (CW)
Isolation (at Center Wavelength) ≥25 dB
Performance Graph
Insertion Loss (Without Connectors) 1.6 dB
Polarization Dependent Loss (PDL) ≤0.25 dB
Return Loss >50 dB
Fiber SM600
  • Not recommended for high-power pulsed applications. The maximum power handling of this isolator is reduced with the addition of connectors .



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