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Single Mode Polarizing Fiber

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Polarizing Optical Fiber for 830 nm and 1064 nm




  • Polarizes Light Transmitted Through Fiber
  • High Briefringence Produces High Polarization Extinction Ratios
  • 830 nm or 1060 nm Design Wavelength
  • 100 nm, Broad, Stable Operating Window

Features

  • 100 nm Bandwidth
  • >30 dB Extinction Ratio
  • Design Wavelengths: 830 nm or 1060 nm
  • Applications:
    • Fiber Optic Gyroscopes
    • Coherent Communications
    • Current Sensors

Thorlabs' Polarizing (PZ) fibers, also known as Zing™ fibers, are specialty optical fibers in which one and only one polarization state is allowed to propagate. Light with all other polarization directions experience significant optical loss and thus are not propagated through the fiber. To create this effect, our PZ fiber utilizes bow-tie geometry to create an extreme birefringence. This birefringence ensures that only light with the proper polarization direction is guided through the fiber, whereas all other polarization directions experience high loss.

These PZ fibers offer a broad polarizing bandwidth (~100 nm), high extinction ratio (>30 dB), and low attenuation. The polarizing window and extinction ratio can be tuned by coiling the PZ fiber (referred to as fiber deployment). Coiling the fiber to smaller diameters will narrow the polarization window and shift the window to lower wavelengths (see Graphs tab for more information). The polarizing window is defined between the 20 dB Fast Edge and 1 dB Slow Edge (see graph to the right). Straight or coiled, Thorlabs' PZ fibers deliver top-of-the-line performance.

PZ fibers are all-fiber devices with several advantages over in-line polarizers, such as lower insertion loss, higher extinction ratio, and no complex component assemblies or bulky packaging (see the PZ Tutorial tab). This cost-effective fiber delivers a high extinction ratio (ER), a bandwidth so wide that it will polarize at the design operating wavelength (830 nm for HB830Z and 1064 nm for HB1060Z) even if the fiber is stressed, an ER and insertion loss that is stable with temperature, and long-term reliability in use. Our PZ fiber cleaves, handles, and splices just as any other fiber would and is compatible with standard PM fiber systems (both panda and bow-tie). This fiber also terminates just like any other PM fiber that requires low-stress epoxy and alignment of the key to the axis.

It is important to note that PZ fibers are not the same as Polarization-Maintaining (PM) fibers. While PM fibers maintain the linear polarization state when the polarization direction is aligned with the birefringence axis, they are also capable of propagating any polarization direction. Unlike PM fibers, PZ fibers suffer no polarization cross-talk, which makes them ideal for polarization-sensitive applications.

These fibers can be ordered as connectorized patch cables using our custom cables configurator.

Item #Polarizing Windowa,bCladding DiameterCoating DiameterMFDc NAdCutoff
(Typ.)e
AttenuationBeat LengthExtinction Ratioa20 dB Fast Edgea,b1 dB Slow Edgea,b
HB830Z 820 ± 30 nm 80 ± 1 µm 170 µm ± 3% 5.0 µm 0.14 400 - 600 nm ≤0.02 dB/m
@ 830 nm
≤1.04 mm
@ 830 nm
≥30 dB ≤790 nm >850 nm
HB1060Z 1064 ± 50 nm 125 ± 1 µm 245 µm ± 5% 7.0 µm 0.14 ≤0.02 dB/m
@ 1064 nm≤0.8 mm
@ 633 nm≥30 dB≤1015 nm≥1105 nm
  • Typical polarization performance with deployment conditions of 5 m fiber length in a Ø89 mm (Ø3.5") coil
  • Refer to graph to the top right for definition
  • Mode Field Diameter (MFD) is specified as a nominal value. It is the diameter at the 1/e2 power level in the near field. For more information, please see the MFD Definition tab above.
  • Numerical Aperture (NA) is specified as a nominal value.
  • Typical value, actual cutoff value is dependent upon fiber deployment

 

FiberHB830ZHB1060Z
Polarizing Windowa,b 820 ± 30 nm 1064 ± 50 nm
Cladding Diameter 80 ± 1 µm 125 ± 1 µm
Coating Diameter 170 µm ± 3% 245 µm ± 5%
Mode Field Diameterc 5.0 µm 7.0 µm
Numerical Apertured 0.14 0.14
Cutoff Wavelength (Typical)e 400 - 600 nm  
Attenuation ≤0.02 dB/m @ 830 nm ≤0.02 dB/m @ 1060 nm
Beat Length ≤1.04 mm @ 830 nm ≤0.8 mm @ 633 nm
Extinction Ratioa ≥30 dB
20 dB Fast Edgea,b ≤790 nm ≤1015 nm
1 dB Slow Edgea,b >850 nm ≥1105 nm
Core-Cladding Concentricity ≤1 µm ≤0.75 µm
Coating-Cladding Offset ≤10 µm
Coating Material Dual Acrylate
Operating Temperature -40 to 85 °C
Proof Test Level (1.4 GN/m2) 100 kpsi
  • Typical polarization performance with deployment conditions of 5 m fiber length in a Ø89 mm (Ø3.5") coil
  • Refer to graph to the right for definition
  • Mode Field Diameter (MFD) is specified as a nominal value. It is the diameter at the 1/e2 power level in the near field. For more information, please see the MFD Definition tab above.
  • Numerical Aperture (NA) is specified as a nominal value.
  • Typical value, actual cutoff value is dependent upon fiber deployment

 

PZ Fiber Overview

Polarizing (PZ) fiber (i.e., Zing™ fiber) is a specialty optical fiber that will guide only one polarization direction, thus polarizing light that is propagated through the fiber. This form of single-polarization transmission carries several benefits over single mode (SM) or polarization-maintaining (PM) fiber. While PM fiber maintains the polarization direction that is aligned with the birefringence axis, cross talk occurs since the PM fiber is capable of guiding any polarization direction. SM fiber can be stressed to induce birefringence , which causes the fiber to behave much like a wave plate. While the polarization axis can be manipulated in this case, the SM fiber does not polarize the light.

In contrast, PZ fiber guides only one polarization direction; all other directions are unguided. As a result, PZ fibers will polarize the light guided through it, creating excellent suppression of unguided polarization directions. While in-line polarizers can provide between 20 and 30 dB suppression of unwanted polarization directions, PZ fibers can realize >30 dB suppression at the design wavelength. Additionally, by stressing the fiber, the polarization window can be manipulated and the user can realize suppression of over 35 dB. Because stress on a PZ fiber can alter its operation, "deployment" of the fiber becomes an essential quality. Deployment refers to how the fiber is laid out, whether it is straight, coiled, or randomly piled.

Using PZ Fiber

It is important to note that the deployment of the PZ fiber is key to its performance. Our PZ fiber has a very wide polarizing window, the width and center wavelength of which depends on how the fiber is deployed (see the Graphs Tab). In nominal usage of the fiber around its designed wavelength, the PZ fiber will polarize for any deployment. For other usage, however, the user should ensure that the deployment shifts the polarization window such that the window overlaps the source. This method works best with a narrow linewidth souce such as a laser. For broadband sources, the PZ fiber needs to be coiled appropriately such that the width and center wavelength of the polarization window can overlap the source.

It is advantageous to use a depolarizer at the input of the PZ fiber because it ensures the light is evenly polarized, avoiding power variations that can occur with all types of polarizers. The depolarizer can be made from two sections of PM fiber spliced at 45° (length will depend on the source). In this system, the PZ fiber is also typically coupled to the depolarized output at 45° to take full advantage of the depolarizing effect (Note: If using patch cables, one termination should be rotated 45° relative to the other where the depolarizer fiber meets the PZ fiber, by offsetting the key in either fiber at 45°). When the input light to the PZ fiber is depolarized, the light incident upon the fast and slow axes of the PZ fiber is equal, resulting in consistent 3 dB rejection and stable output power. The figure below shows an example system for using our polarizing fibers with an unpolarized light source.

FiberABCD
HB830Z 830 nm Laser Source SM800 Fiber Coiled HB830Z Fiber Aligned PM780-HP Fiber
HB1060Z 1060 nm Laser Source SM980 Fiber Coiled HB1060Z Fiber Aligned PM980-XP Fiber

Coiling our PZ fiber to smaller diameters will create a narrower polarization window and blueshift the center wavelength. Coiling the PZ fiber can result in a better polarization extinction ratio, although it can lead to greater loss. If loss is too high, the coil is too tight; conversely, if the polarization extinction ratio is too low, the coil is not tight enough. For example, to achieve an extinction ratio of 35 dB with our HB1060Z PZ Fiber, 2 m of fiber is coiled into Ø5 cm loops. The diagram above demonstrates how this is implemented. Unpolarized light was sent into the PZ fiber, which is coiled to produce the desired effect. The PZ fiber was then spliced into a PM fiber, which goes out to the system. For additional performance stability, it is recommended to use 3 - 5 m of HB1060Z fiber or 4 - 10 m of HB830Z. However, due to the high birefringence of the PZ fiber, the polarization window will still be broad, giving the user a wide variety of packaging and deployment options.

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