Metrotek's Product

 

I. Introduction

General Phtotonics Corporation’s Polarization Controllers use a mechanical fiber squeezer (shown in the following figures), which can be rotated about the fiber to convert an arbitrary input polarization to any desired output polarization. Tightening the knob on the fiber squeezer applies pressure to the fiber sandwiched between two pressure plates in the center portion of the device, producing a linear birefringence in this portion of the fiber with its slow axis in the direction of applied pressure. The retardation between the slow and fast axes can be varied between 0 and 2p by changing the applied pressure. In addition, the induced birefringent axes can be varied from 0 to more than p/2 by rotating the fiber squeezer about the fiber. This way, an all fiber Babinet-Soleil compensator is created.

II. Two polarization controller versions are available

  1. The PLC-003 (standard) is the in-line version of the polarization controller. It can be inserted in a fiber optic system to control the polarization state of light without disconnecting any part of the system. It can be used by simply inserting a length of fiber into the slot located on top of the device.

  2. The PLC-004 (with female connectors) come with a connector terminated length of specially coated fiber already inserted in the device, enabling the end-user to attach connector terminated fibers to their input and output ports.

III. Operating Instructions

Note: Please Follow Steps 1-4 for the PLC-003 polarization controller only.

Step 1. Remove the two fiber clamps on the left and right ends of the device by unscrewing the four 4-40 hex screws. Care should be taken when removing the center cap by unscrewing the two 2-56 hex cap screws to prevent some small parts in the cap from dropping out and getting lost.

Step 2. You will find a slot in each of the two side blocks and a slot in the center stainless steel part. Rotate the center part and align its slot with those in the two side blocks.

Step 3. Locate a section of fiber (with 250 um coating*) in your setup and drop a section of this fiber into the slot. Put the two fiber clamps back on top of the fiber. Make sure the fiber is straight in the device and securely held by the fiber clamps in the V-grooves below. The pressure on the fiber clamps should be just enough to hold the fiber. Do not overly tighten the screws.

Step 4. Put the center cap back on top of the stainless steel part and tighten the two hex cap screws. Now you are ready to operate. Go to Step 6 for additional operation instructions.

Note: Please follow Steps 5 for the PLC-004 only.

Step 5. Connect the polarization controller in line with your set-up by using the fiber bulkhead connectors (PLC-004).

Step 6. Launch light into the fiber going through the polarization controller which in turn is connected to the polarization sensitive device. Monitor the output power with the help of an optical power meter. Follow Steps 7-8 to optimize the polarization state for the device, indicted by a maximum power reading.

Step 7. Apply pressure to the center portion of the fiber by tightening the knob on the rotatable fiber squeezer while monitoring the optical power. If applying pressure causes an increase in monitored optical power, keep increasing the pressure until the monitored optical power starts to decrease.

NOTE
Please do not apply excessive pressure to the fiber by overtightening the screw. In most cases, sufficient pressure can be generated by tightening the screw half way.

Step 8. Rotate the fiber squeezer while maintaining the applied pressure on the fiber, to fine-tune the output polarization. Adjust the pressure and orientation of the fiber squeezer iteratively until the maximum monitored optical power is obtained. This indicates that the optimal polarization is achieved. In most cases, the desired polarization can be achieved in 2 or 3 iterations.

Step 9. If applying additional pressure causes little change in the monitored optical power, or causes the optical power to decrease, release the pressure and rotate the center portion to a new position. Repeat Steps 7 and 8 if turning the knob causes an increase in monitored optical power. Following this procedure will result in a minimum number of iterations.

*Most of such fibers have a 250um buffer coating. Fibers with a 900um jacket are not recommended. However, 900um fibers can be accommodated through the use of our specially designed jumpers.


For more information, contact:
Metrotek
Phone: (727) 547-8307
Fax: (727) 547-0687

E-mail: fiberoptics@metrotek.com

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