Fiber Holding Block

• Slots for Common Vytran Fiber Inserts (Sold Separately Below)
• Vacuum Port for Small Fiber Retention When Used with Vacuum-Compatible Inserts (Sold Separately Below)
• Lid Lever for Overcoming Magnet Force
• Mounting Features:
  • 8-32 (M4 x 0.7) Tapped Hole for Post Mounting
  • 1/4" (M6) Counterbores for Breadboard Mounting

The FHB2(/M) Fiber Holding Block uses a top and bottom insert (sold separately below) to retain fiber for processing or coupling applications. A vacuum pump (not offered by Thorlabs) aids in the retention of small fibers when used with vacuum-compatible bottom inserts (available separately below). The block can be Ø1/2" or Ø1" post-mounted or directly mounted to a breadboard or other optomech using the tapped hole or counterbores in the base, respectively. The block's base can also be removed and rotated 180° for flexibility with mounting and vacuum tube positioning.

To use the FHB2(/M) block, first mount it as desired and install the inserts as detailed below. If using a vacuum pump, attach 5/32" (4 mm) OD tubing to the block, pull lightly on the orange sleeve protruding from the vacuum fixture to secure the tube, connect the tubing to the pump, and turn the pump on. Lastly, insert the fiber, close the block's lid, and raise the lever to engage the clamp magnets. We recommend using a vacuum pump that can provide vacuum equal to or better than -27 kPa (-203 mmHg, -270 mbar, -8 "Hg) and with a flow rate of 5 L/min or more.

Insert Installation
To install a bottom V-groove insert in the fiber block base, first orient the insert such that the desired V-groove side is facing up. Place the insert in the base, ensuring it is fully seated and that the end is flush on the side of the block where the bare fiber will protrude. To secure the insert, gently tighten the two 4-40 nylon-tipped setscrews using the included 0.05" hex key. To remove the bottom insert, back off the two set screws (one full turn counter-clockwise should be sufficient). The insert should slide freely side-to side and can easily be removed by "overhanging" one end of the insert and then lifting it up and out with the hex key. The top inserts can be similarly installed and removed using the two setscrews accessible on the front side of the block's top.

• Top Inserts for Fiber Holding Blocks
• For Fiber Outer Diameters (Cladding/Coating) from 57 µm to 3.198 mm (See the Fiber Holder Inserts Tab for Information on Choosing Inserts)
• Single-Sided and Dual-Sided Inserts Available (See Table G2.1)

These top inserts are placed in the FHB2 fiber holding block along with either a bottom or transfer insert to secure the fiber. The inserts clamp the cladding, buffer, or coating of the fiber and can accommodate outer diameters of up to 3.198 mm. The Fiber Holder Inserts tab includes information to aid in selecting and installing the correct combinations of top and bottom inserts to accommodate different fiber diameters.

The VHA standard top inserts come in single-sided and dual-sided versions. These standard inserts can also be used in our Automated Glass Processors, LDC401 Series of Fiber Cleavers, FPS301 Stripping and Cleaning Station, and LFS4100 Splicing System.

• Clamp Fiber Outer Diameters from 57 µm to 3.198 mm when Used with Top Inserts (Available Above)
• VHD and VHF Series of Inserts Have Holes for Vacuum Suction to Aid in Retention of Small Fibers when Used with Vacuum Pump (See the Table G3.1)
• VHF Transfer Inserts are Used with VHT1 Transfer Clamp to Aid in Transferring a Fiber with ≤Ø1.047 mm Coating between Compatible Vytran Systems
  • GPX3400 and GPX3600 Glass Fiber Processing Stations
  • GPX4000LZ CO₂ Laser Glass Processor
  • LDC401 Series and LDC450B Fiber Cleavers
  • FPS301 Fiber Preparation Station
  • LFS4100 Splicer
• Interchangeable by the User

These bottom inserts each have a V-Groove on one or both sides that can accommodate a range of diameters (as indicated in Table G3.1). Bottom inserts are sold individually, and one is required to use the fiber holding block. The top (available above) and bottom fiber holder inserts can be paired in different combinations, outlined on the Fiber Holder Inserts tab above, to accommodate fiber with outer diameters from 57 µm to 3.198 mm.

Three types of bottom inserts are available. Standard bottom inserts for fiber with an outer diameter <Ø1.047 mm have vacuum holes to help position the fiber in the groove. For certain fiber diameters, we also offer transfer inserts (Item #s beginning with VHF) designed to work with the VHT1 transfer clamps (available below) that aid in moving the fiber between compatible Vytran stations while maintaining coarse alignment. The VHE series of fiber holder bottom inserts have a V-Groove on one (VHE25 and VHE30) or both sides (VHE10, VHE15, and VHE20) but do not include vacuum holes. The VHF transfer inserts and VHE bottom inserts can both be installed in other, compatible Vytran stations, although the VHE bottom inserts cannot be used with the VHT1 transfer clamp.

If using the FHB2(/M) block as a stand-alone device, the VHD series or VHE series inserts will be sufficient. If moving fibers between the holding block and Vytran systems, a transfer insert and VHT1 transfer clamp (available below) can be used for certain fiber sizes, as indicated in Table G3.1. For information on how to assemble transfer inserts, see the Fiber Holder Inserts tab.

• Clamp and Graphite V-Grooves Used with Transfer Bottom Inserts to Move Fiber Between Vytran Systems
• One VHT1 Transfer Clamp Required with Each Transfer Bottom Insert
• Transfer Clamps are Also Compatible with GPX Fiber Processors, LDC401 Series and LDC450B Fiber Cleavers, the FPS301 Fiber Preparation Station, and the LFS4100 Fusion Splicer
• Graphite V-Grooves for Supporting Fibers ≤Ø550 µm
• V-Grooves Accept Diameters from 80 µm to 550 µm

These Transfer Clamps and V-Grooves are used with the VHF Transfer Bottom Inserts sold above to move a single fiber between the FHB2(/M) fiber block and various Vytran systems with minimal loss of alignment. For example, a fiber can be placed in a transfer insert and cleaved using the LDC401 Fiber Cleaver. Then, the entire transfer insert and fiber can be moved to a glass processor for splicing.

The VHT1 clamp secures transfer inserts with a magnetic lid that prevents axial movement of the fiber and can be used to hold the insert during transport without touching the fiber itself. For fibers with diameters ≤550 µm, a graphite V-groove is available to support the fiber during processing (please see Table G4.1 for more information). To provide extended support along the length of the fiber and reduce the amount of overhang during processing, we also offer 0.594" long V-grooves (Item #s VHG125L, VHG250L, and VHG500L). The graphite V-grooves are secured by tightening two setscrews on the transfer insert. For information on how to assemble transfer inserts, see the Fiber Holder Inserts tab.

Click to Enlarge
Figure G5.2  The Double-V-Slot with Pins inserts feature eccentric adjustment pins that are used to bring two fibers into very close proximity for splicing together. The VHD320C insert is shown above.

• Bottom Inserts with Grooves for Holding Multiple Fibers
• Used When Creating Fused Couplers or Combiners
• Vacuum Holes for Aligning Fibers in V-Grooves or Slots
• Multiple Insert Types Available (See Table G5.1 for Options)

Multi-Fiber Inserts are designed for applications requiring two or three fibers to be tapered and fused together, such as when making wavelength division multiplexers, fused fiber couplers, or power combiners.

Side-by-Side inserts have a U-shaped groove for holding two fibers tightly together in parallel. Double-V-Slot inserts feature two parallel V-grooves on the same side of the insert that each hold a single fiber. The Double-V-Slot with Pins inserts additionally feature eccentric offset adjustment pins that are used to bring the two fibers in close contact during processing (see Figure G5.2). Triple-V-Slot inserts have a V-groove in the middle and two V-grooves adjacent on both sides that allow a signal fiber to be fused with two pump fibers.

The grooves machined into the inserts ensure the fiber is centered within the fiber holder. Vacuum holes at the bottom of the transfer inserts are used for holding and aligning small fibers within the V-groove. Recommended top inserts for each multi-fiber insert are indicated in Table G5.1. Alignment of the fibers will not be maintained when these inserts are transferred between systems.

These inserts are also compatible with our automated glass processors.