Castech's high power Optical Circulator could routes incoming signals from Port1 to Port2, incoming port2 signals to port3. This component has excellent performance of low insertion loss, low PDL and high stability.
Castech's high power Optical Circulator could routes incoming signals from Port1 to Port2, and incoming port2 signals to port3. This component has excellent performance of low insertion loss, low PDL and high stability. The parameters can be customized according to customer requirements.
Operating Wavelength Range
Isolation in band at 23℃
Insertion Loss at 23℃
Polarization Dependent Loss
Return Loss (Input/Output)
HI1060Fiber/PM Fiber or Specify
Optical Power (Average)
3, 5, 10Wor Specify
Peak Pulse Power
10KW or Specify
980,1030,1064 or other
(900μm Loose Tube)
(3mm Loose Tube)
The main component of the optical isolator is the Faraday rotator. The magnetic field B, applied to the Faraday rotator causes a rotation in the polarization of the light due to the Faraday effect. The angle of rotation θ is given by θ=vBL, where v is the Verdet constant of the magneto-optic material, and L is the length of the magneto-optic material. Specifically for an optical isolator, the values are chosen to give a rotation of 45°.
Faraday rotator is an important optical element in an isolator. The characteristics of a Faraday rotator include a high Verdet constant, low absorption coefficient, low non-linear refractive index and high damage threshold. The two most commonly used materials for the 700–1100 nm range are terbium doped borosilicate glass and terbium gallium garnet crystal (TGG). For infrared wavelength range, typically for the 1300-4000nm, yttrium iron garnet crystals are used (YIG).
Faraday rotator provides non-reciprocal rotation while maintaining linear polarization. That is, the polarization rotation due to the Faraday rotator is always in the same relative direction. So in the forward direction, the rotation is positive 45°. In the reverse direction, the rotation is −45°. This is due to the change in the relative magnetic field direction, positive one way, negative the other. This then adds to a total of 90° when the light travels in the forward direction and then the negative direction. This allows the higher isolation to be achieved.
Optical isolator according to its physical principles can be divided into polarization dependent isolator and polarization independent isolator.The polarization dependent isolator, or Faraday isolator, is made of three parts, an input polarizer (polarized vertically), a Faraday rotator, and an output polarizer, called an analyser (polarized at 45°).
Polarization dependent isolators are typically used in free space optical systems. This is because the polarization of the source is typically maintained by the system. In optical fibre systems, the polarization direction is typically dispersed in non polarization maintaining systems. Hence the angle of polarization will lead to a loss.
The polarization independent isolator is made of three parts, an input birefringent beam displacer, a Faraday rotator, a half-waveplate, and an output birefringent beam displacer.
Polarization independent isolators are typically used in fiber laser systems to maintain frequency stability, such as industrial processing areas etc.
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