Manual Fiber Polarization Controllers
Full Polarization Control with Paddles
The animation above shows an ideal case. The fractional retardance of each paddle depends upon many factors, including the wavelength, the number of fiber loops, and the fiber type. For more details, please see the Operation
- Convert Between Linear, Circular, and Elliptical Polarization States
- Operates over Full Fiber Bandwidth
- Available with 1 of 6 Preloaded Fibers (See Specs Tab for Details)
- Empty Controllers Accept Bare Fiber and ≤Ø900 µm Jacketed Fibers
- FC/PC- or FC/APC-Connectorized Fibers (2.0 mm Narrow Key)
- Three Loop Diameters Available
- Three-Paddle Controllers: 1.06" or 2.2"
- Two-Paddle Controllers: 0.71"
Thorlabs' Fiber Polarization Controllers use stress-induced birefringence produced by wrapping the fiber around two or three spools to create independent wave plates that will alter the polarization of the transmitted light in a single mode fiber. The fast axis of the fiber is in the plane of the spool, allowing an arbitrary input polarization state to be adjusted by rotating the paddles. See the animation to the right and the Operation tab for more details.
The controllers are available in a 3-paddle configuration with either 1.06" or 2.2" diameter loops as well as a mini 2-paddle configuration with 0.71" diameter loops. Thorlabs offers an empty controller in each style to allow the user to insert a fiber of their choice. They are also available preloaded with one of six fiber types, although the preloaded fiber may be replaced with another fiber should a different wavelength range be required for future applications. See the Specs tab for the available configurations. All of our controllers accept bare and ≤Ø900 µm jacketed single mode fibers. For fibers with higher bend loss (e.g., Corning's SMF-28e+), use the FPC560, which features the largest spools and therefore the least bending.
Thorlabs also offers a compact PLC-900 In-Line Polarization Controller. This controller creates a single continously variable wave plate similar to a Soleil-Babinet compensator, which allows polarization control over the full Poincaré sphere.
3-Paddle Fiber Polarization Controllers
|Number of Paddles||3|
|Loop Diameter||1.06" (27 mm)||2.2" (56 mm)|
|Footprint (L x W)||8.5" x 1.0" (215.9 mm x 25.4 mm) in Narrowest Configuration|
8.5" x 2.51" (215.9 mm x 63.8 mm) in Widest Configuration
|12.5" x 1.0" (317.5 mm x 25.4 mm) in Narrowest Configuration|
12.5" x 4.85" (317.5 mm x 123.2 mm) in Widest Configuration
|Specifications for Preloaded Fiber (As Shipped by Thorlabs)|
|Operating Wavelength Rangea||N/A||1260 - 1625 nm||N/A||1260 - 1625 nm|
|Design Wavelengthb||N/A||1310 nm||N/A||1310 nm|
|Mode Field Diameter||N/A||8.6 ± 0.4 µm @ 1310 nm|
9.7 ± 0.5 µm @ 1550 nm
|N/A||9.2 ± 0.4 µm @ 1310 nm|
10.4 ± 0.5 µm @ 1550 nm
|Cladding||N/A||125 ± 0.7 µm||N/A||125 ± 0.7 µm|
|Coating||N/A||245 ± 5 µm||N/A||245 ± 5 µm|
|Cutoff Wavelength||N/A||≤1260 nm||N/A||<1260 nm|
|Jacketing||N/A||Ø900 µm Tight Buffer||N/A||Ø900 µm Tight Buffer|
|Loop Configuration||N/A||2 Loops - 3 Loops - 2 Loops||N/A||3 Loops - 6 Loops - 3 Loops|
|Fiber Length||N/A||2 m||N/A||5 m|
|Working Fiberc||N/A||70 cm||N/A||145 cm|
|Bend Loss||N/A||≤0.1 dB||≤0.1 dB||N/A||≤0.1 dB||≤0.1 dB|
Miniature 2-Paddle Fiber Polarization Controllers
|Number of Paddles||2|
|Loop Diameter||0.71" (18 mm)|
|Foot Print (L x W)||3.06" x 0.5" (77.72 mm x 12.70 mm) in Narrowest Configuration|
3.06" x 1.75" (77.72 mm x 44.5 mm) in Widest Configuration
|Specifications for Preloaded Fiber (As Shipped by Thorlabs)|
|Operating Wavelength Rangea||N/A||450 - 600 nm||600 - 800 nm||780 - 970 nm||980 - 1060 nm||1260 - 1625 nm|
|Design Wavelengthb||N/A||488 nm||633 nm||780 nm and 850 nm||980 nm||1310 nm|
|Mode Field Diameter||N/A||3.3 µm @ 488 nm|
3.4 µm @ 514 nm
|4.3 µm @ 633 nm|
4.6 µm @ 680 nm
|5.0 ± 0.5 µm @ 850 nm||5.9 µm @ 980 nm|
6.2 µm @ 1060 nm
|8.6 ± 0.4 µm @ 1310 nm|
9.7 ± 0.5 µm @ 1550 nm
|Cladding||N/A||125 ± 1.0 µm||125 ± 1.0 µm||125 ± 1.5 µm||125 ± 0.5 µm||125 ± 0.7 µm|
|Coating||N/A||245 ± 15 µm||245 µm ± 5%||245 ± 15 µm||245 ± 10 µm||245 ± 5 µm|
|Cutoff Wavelength||N/A||400 -0/+50 nm||550 ± 50 nm||730 ± 30 nm||920 ± 50 nm||≤1260 nm|
|NA||N/A||0.10 - 0.14||0.10 - 0.14||0.13||0.14||0.14|
|Jacketing||N/A||Ø900 µm Hytrel Tubing||Ø900 µm Tight Buffer|
|Loop Configuration||N/A||3 Loops - 3 Loops||3 Loops - 3 Loops||4 Loops - 4 Loops||2 Loops - 2 Loops||3 Loops - 3 Loops|
|Fiber Length||N/A||2 m +7/-0 cm|
|Working Fiberc||N/A||80 cm||80 cm||75 cm||85 cm||80 cm|
|Bend Loss||N/A||<0.1 dB|
These manual polarization controllers utilize stress-induced birefringence to create two or three independent fractional wave plates to alter the polarization in single mode fiber that is looped around two or three independent spools to create the independent fractional wave plates (fiber retarders). The amount of birefringence induced in the fiber is a function of the fiber cladding diameter, the spool diameter (fixed), the number of fiber loops per spool, and the wavelength of the light. (NOTE: the desired birefringence is induced by the loop in the fiber, not by the twisting of the fiber paddles). The fast axis of the fiber, which is in the plane of the spool, is adjusted with respect to the transmitted polarization vector by manually rotating the paddles. To transform an arbitrary input polarization state into an arbitrary output polarization state, a combination of three paddles (a quarter-wave plate, a half-wave plate, and a quarter-wave plate) or two paddles (quarter-wave plate and a quarter-wave plate) is used. The retardance of each paddle may be estimated from the following equation:
Here, φ is the retardance, a is a constant (0.133 for silica fiber), N is the number of loops, d is the fiber cladding diameter, λ is the wavelength, and D is the loop diameter. While this equation is for bare fiber, the solution for Ø900 µm jacketed fiber will be similar enough that the results for this equation can still be used (i.e., the solution will not vary by a complete loop N for Ø900 µm jacketed fiber).
Three-Paddle Polarization Controllers
A three-paddle polarization controller combines a quarter-wave plate, half-wave plate, and quarter-wave plate in series to transform an arbitrary polarization state into any other polarization state. The first quarter-wave plate would transform the input polarization state into a linear polarization state. The half-wave plate would rotate the linear polarization state, and the last quarter-wave plate would transform the linear state into an arbitrary polarization state. This is illustrated in the animation on the Overview tab. Therefore, adjusting each of the three paddles (fiber retarders) allows complete control of the output polarization state over a broad range of wavelengths from 500 to 1600 nm). Using FPC030 as an example, a plot of calculated retardation per paddle versus wavelength is shown in Figure 1 for a fiber with a cladding diameter of 125 μm. For fiber with a cladding diameter of 80 μm, the retardation per paddle versus wavelength is shown in Figure 2. The FPC030 has a loop diameter of 27 mm.
Click to EnlargeFigure 1:
Plot of the retardance per paddle for silica fiber with Ø125 µm cladding on the FPC030, which has a loop diameter of 27 mm.
Click to EnlargeFigure 2:
Plot of the retardance per paddle for silica fiber with Ø80 µm cladding on the FPC030, which has a loop diameter of 27 mm.
Figures 3 and 4 show the results for Ø125 µm and Ø80 µm clad fiber, respectively, for the FPC560 controller, which has three paddles with a loop diameter of 56 mm. The larger loop diameter is ideal for fibers with higher bend loss.
Click to EnlargeFigure 3:
Plot of the retardance per paddle for silica fiber with Ø125 µm cladding on the FPC560, which has a loop diameter of 56 mm.
Click to EnlargeFigure 4:
Plot of the retardance per paddle for silica fiber with Ø80 µm cladding on the FPC560, which has a loop diameter of 56 mm.
Miniature Two-Paddle Polarization Controller
The miniature two-paddle polarization controllers use two quarter-wave plates to transform an arbitrary polarization state into any other polarization state. In the two-paddle configuration, however, the control of the polarization will be coupled between the two paddles. The design of the FPC020 allows complete control of the output polarization state over a broad range of wavelengths. Figures 5 and 6 show the calculated retardation per paddle for Ø125 µm and Ø80 µm clad bare fiber, respectively, for the FPC020, which has a loop diameter of 18 mm.
Click to EnlargeFigure 5:
Plot of the retardance per paddle for bare silica fiber with Ø125 µm cladding on the FPC020, which has a loop diameter of 18 mm.
Click to EnlargeFigure 6:
Plot of the retardance per paddle for bare silica fiber with Ø80 µm cladding on the FPC020, which has a loop diameter of 18 mm.