patents, our isolators typically have higher transmission and isolation than other isolators, and are smaller than other units of equivalent aperture. When the light encounters the input birefringent beam displacer, it will be deflected away from the collimating lens and into the walls of the isolator housing, preventing the reverse mode from entering the input fiber. The faraday rotator is a non-reciprocal rotator, so it will cancel out the rotation introduced by the half wave plate for the reverse mode light. This achieves greater isolation than the single-stage design.īack-reflected light will encounter the second birefringent crystal and be split into two beams with their polarizations aligned with the forward mode light. In a dual-stage isolator, the light then travels through an additional Faraday rotator, half-wave plate, and birefringent beam displacer before reaching the output collimating lens. A Faraday rotator and a half-wave plate rotate the polarization of each branch before they encounter a second birefringent crystal aligned to recombine the two beams. In a polarization independent fiber isolator, the incoming light is split into two branches by a birefringent crystal (see Figure 3). Light is deflected away from the input path and stopped by the housing. A single-stage, polarization-independent isolator. Hence, the light will either be reflected or absorbed.įigure 3. This results in a net rotation of 90° with respect to the input polarizer, and thus, the POP is now perpendicular to the transmission axis of the input polarizer. It then passes through the Faraday rotator rod, and the POP is rotated another 45° in the positive direction. Light traveling backwards through the isolator will first enter the output polarizer, which polarizes the light at 45° with respect to the input polarizer. In a dual-stage isolator, the light exiting the output polarizer is sent through a second Faraday rotator followed by an additional polarizer in order to achieve greater isolation than a single-stage isolator. Therefore, the light leaves the isolator with a POP of 45°. Finally, the light exits through the output polarizer which has its axis at 45°. The Faraday rotator will rotate the plane of polarization (POP) by 45° in the positive direction. Laser light, either polarized or unpolarized, enters the input polarizer and becomes vertically polarized. In this example, we will assume that the input polarizer's axis is vertical (0° in Figure 2). Light propagating in the reverse direction is rejected by the input polarizer. A single-stage, polarization-dependent isolator. This light's polarization is now perpendicular to the transmission axis of the input polarizer, and as a result, the energy is either reflected or absorbed depending on the type of polarizer.įigure 2. In the reverse direction, the Faraday rotator continues to rotate the light's polarization in the same direction that it did in the forward direction so that the polarization of the light is now rotated 90° with respect to the input signal. The output light is now rotated by 45° with respect to the input signal. The Faraday element rotates the input light's polarization by 45°, after which it exits through another linear polarizer. The input polarizer works as a filter to allow only linearly polarized light into the Faraday rotator. V: the Verdet Constant, a property of the optical material, in radians/T ĭ: the path length through the optical material in meters.Īn optical isolator consists of an input polarizer, a Faraday rotator with magnet, and an output polarizer. Faraday Rotator's Effect on Linearly Polarized Light Faraday Rotation For product customization or special requirements, please contact Lfiber’s sales department for availability.Figure 1.So that if any connectors needed, for the pigtail type it’s better to choose the 900μm loose tube jacket instead of the 250μm bare fiber. Bare fiber should not support the weight of the connector.For device with connectors, IL is 0.3dB higher, RL is 5.0dB lower.For CW high-power optical interconnection, we recommend fusion splice without connectors.The high power fiber optic circulator is customizable and the above specifications are subject to change without notice.Specifications of High Power Fiber Optic Circulator
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