It allows the transmission of optical signals in the forward direction while blocking reflected energy back at the source to reduce the interference effect. So it is usually widely used in optical fiber amplifier.An optical isolator is a key component in a fiber optic system. While polarization dependent isolator allows only the light polarized in a specific direction, polarization independent isolator transmit all polarized light. The picture shows the propagation of light through a polarization independent isolator.
Instead of being focused by the second birefringent wedge, the rays diverge. Now the o-ray is at 90°, and the e-ray is at 0°. The Faraday Rotator again rotates both the rays by 45°. Light traveling in the backward direction is separated into the o-ray at 45, and the e-ray at −45° by the birefringent wedge. The output birefringent wedge then recombines the two components. This means the o-ray is now at 45°, and the e-ray is at −45°. The Faraday rotator rotates both the o-ray and e-ray by 45°. Light traveling in the forward direction is split by the input birefringent wedge into its vertical (0°) and horizontal (90°) components, called the ordinary ray (o-ray) and the extraordinary ray (e-ray) respectively. The polarization independent isolator also consists of three parts, an input birefringent wedge, a Faraday rotator, and an output birefringent wedge.
#Polarization independent optical isolator free#
Because the polarization of the source is typically maintained by the system, polarization dependent isolator is widely used in free space optical systems. The Faraday rotator is chosen to give a 45° rotation. For a polarization dependent isolator, the angle between the polarizer and the analyser, is set to 45°.
The picture shows us a Faraday rotator with an input polarizer, and an output analyser. Since the polarizer is vertically aligned, the light will be extinguished. This means the light is polarized horizontally. The Faraday rotator will again rotate the polarization by 45°. The analyser then enables the light to be transmitted through the isolator. Light traveling in the backward direction becomes polarized at 45° by the analyser. The Faraday rotator will rotate the polarization by 45°. Light traveling in the forward direction becomes polarized vertically by the input polarizer. The polarization dependent isolator consists of three parts, an input polarizer, a Faraday rotator, and an output polarizer. So, what are they and what are the differences between them? This paper will give you the answer. You may be very confused about them as you find that there is only a little difference via their names. The polarizer-based module makes a polarization dependent isolator, and the birefringent crystal-based structure makes a polarization independent isolator. According to the polarization characteristics, optical isolators can be divided into two types, including polarization dependent isolator and polarization independent isolator. At the same time, it prevents the light from going back in the opposite direction. Optical isolator allows a beam of light to stream through a single one way direction. In order to reduce the effects of the interference, an optical isolator is usually used.
These effects on the light beam may cause light energy to be reflected back at the source and interfere with source operation. Connectors and other types of optical devices on the output of the transmitter may cause reflection, absorption, or scattering of the optical signal.
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