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The Working Principle Of Optical Isolator
Jul 21, 2017

Semiconductor lasers and optical amplifiers are very sensitive to reflected light from connectors, fuses, filters, and the like, and cause deterioration of performance. Therefore, it is necessary to block the reflected light with an optical isolator. An optoisolator is a light passive device that allows only light to pass in one direction and block light through the opposite direction. The light reflected by the fiber echo can be well isolated by the optoisolator, and the isolation represents the ability of the optical isolator to isolate (block) the echo. Optical isolator are a very useful device that is often used in optical paths to avoid interference and damage to light sources, pump sources, and other light emitting devices in the optical path. Including polarization-independent in-line optical isolator and polarization-dependent miniaturized optical isolator.

An opto-isolator is a passive optical device that allows only one-way light to pass through, and its working principle is based on non-reciprocity of Faraday rotation.

The light reflected by the fiber echo can be well isolated by the optical isolator. The optical isolator mainly utilizes the Faraday effect of magneto-optic crystals. The characteristics of the optical isolator are: low positive insertion loss, high reverse isolation, and high return loss.

An optoisolator is a passive device that allows the light to pass in one direction and prevents it from passing in the opposite direction. The effect is to limit the direction of the light so that the light can only be transmitted in one direction, and the light reflected by the fiber echo can be controlled by the optical isolator Good isolation, improve light transmission efficiency.

The optical isolator mainly utilizes the Faraday effect of magneto-optic crystals. Faraday effect is Faraday in 1845 first observed that the material does not have optical rotation under the action of the magnetic field through the material in the direction of polarization of light rotation, also known as magnetic rotation effect. The polarized light transmitted in the direction of the magnetic field is proportional to the product of the polarization direction rotation angle θ and the magnetic field intensity B and the material length L. Optical isolator works as shown in Figure 1.

For the forward incident signal light, through the polarizer to become linearly polarized light, Faraday spin-magnetic media and external magnetic field together with the polarization direction of the signal light is rotated 45 degrees, and just make low loss through with the polarizer into 45 Place the analyzer. For the reverse light, the linearly polarized light of the analyzer is rotated by 45 degrees when the medium is rotated, so that the direction of polarization of the reverse light is orthogonal to the direction of the polarizer, completely blocking the transmission of the reflected light The

Faraday magnetic media in the range of 1μm ~ 2μm wavelength is usually used low optical loss of yttrium iron garnet (YIG) single crystal. The new pigtail input and output of the optical isolator has a very good performance, the minimum insertion loss of about 0.5dB, isolation of 35 ~ 60dB, up to 70dB.