Fiber Holding Block
![](https://www.thorlabs.us/Images/GuideImages/15174_FiberBlock_3.jpg)
- Secure Single or Multiple Fibers Using Inserts
- Compatible Inserts for Securing Fibers up to Ø3 mm
- Vacuum-Ready for Small Diameter Fiber Retention
FHB2
Fiber Holding Block
(Inserts and Pump
Sold Separately)
VHA05
Top Insert,
Ø410 µm - Ø1269 µm
VHD750
Bottom Insert,
Ø516 µm - Ø1047 µm
VHF160
Transfer Bottom Insert,
Ø112 µm - Ø208 µm
VHT1
Clamp for
Transfer Inserts
VHG500L
Graphite V-Groove,
Ø450 µm - Ø500 µm
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![](https://www.thorlabs.us/images/tabimages/Fiber_Holding_Clamp_A1-350.jpg)
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Fiber Holder with Inserts, Fiber, and Vacuum Pump Attached
Quick Links |
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Fiber Holding Block |
Top Inserts |
Single-Fiber Bottom Inserts |
Fiber Transfer Clamp & Graphite V-Grooves |
Multi-Fiber Bottom Inserts |
Features
- Post- or Breadboard-Mountable Fiber Holder
- Required V-Groove Inserts Sold Separately Below
- Transfer Inserts Compatible with Select Vytran® Splicers and Glass Processors
- Vacuum Port for Small Fiber Retention (Pump Not Included)
The FHB2(/M) Fiber Holding Block is designed to secure bare fiber for processing or coupling applications and includes a vacuum port on the rear for aid in retaining small fibers while loading/unloading. A wide selection of top and bottom inserts (one of each required to use the holding block) are also available separately below. A lever on the front of block aids in overcoming the force of the clamping magnets. An 8-32 (M4 x 0.7) tapped hole and 1/4"-20 (M6 x 1.0) counterbores in the base enable direct breadboard or post mounting.
To securely hold a fiber with a particular diameter, a set of top and bottom inserts must be installed in the fiber holding block; these are sold separately below and held in place using nylon-tipped 4-40 setscrews with 0.05" (1.3 mm) hexes.
Fiber Holder Inserts Selection Guide (Top Inserts and Standard or Transfer Bottom Inserts)
Introduction
Fiber Holder Inserts, which are designed to hold various sized fibers within the fiber holding block, must be purchased separately. Standard and transfer bottom inserts have V-grooves to hold the fiber, while the top inserts each feature a recessed, flat surface that clamps the fiber against the V-groove in the bottom insert. Each top and bottom insert is sold individually. For multi-fiber inserts, which are used to make fused couplers or combiners, the recommended top inserts are listed in the multi-fiber insert table.
The table below indicates the maximum and minimum outer diameters that can be accommodated by different combinations of top and bottom inserts. It also indicates how far offset the fiber will be for recommended combinations of top and bottom inserts. Note that this outer diameter may be the fiber cladding, jacket, or buffer. If one side of the fiber is being discarded, it is preferable to clamp onto the cladding of this section except in special cases (such as non-circular fiber) where the coating or buffer may be preferable. Sections of fiber that are not being discarded should always be clamped on the coating or buffer in order to avoid damaging the glass.
![V-Groove Inserts](https://www.thorlabs.us/images/tabimages/V-Groove_Plate_Alignment_D1-500.gif)
Each V-groove can accommodate a range of fiber sizes.
Legend | ||
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Best Fit | |
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Second Best Fit: Try these options if the best fit does not incorporate your fiber sizes. | |
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Third Best Fit: Try these options if the other two categories do not incorporate your fiber sizes. |
Fiber Holder Insert Selection Chart
- First, select the bottom insert that matches your fiber size most closely.
Example: For a Ø800 µm fiber, the VHF750 insert is the closest match, since it is only 50 µm smaller. - On the chart below, look to the right of your chosen bottom insert. Select a compatible top insert based on the accepted diameter size range shown in each cell.
Example: For the Ø800 µm example fiber from step 1, the green cell is in the 750 µm groove column for the VHA05 top insert, which has two grooves. The numbers listed in the green cell indicate that this combination of inserts is good for fibers from 728 to 963 µm in diameter. Our Ø800 µm fiber is within this range, so this is a good choice. There are several other options as well that will accommodate a Ø800 µm fiber as well, but the green shading in the chart indicates that the 750 µm groove in the VHA05 provides the best fit. - The second line of numbers in each cell shows the range of offsets that can be expected for any given combination of top and bottom inserts.
Example: If we choose a VHF750 bottom insert and the Ø750 µm groove in the VHA05 top insert, we can use fiber as small as 728 µm, in which case the center of the fiber would sit 23 µm below the surface of the bottom insert. We could also clamp a fiber as large as 963 µm, in which case the center of the fiber would sit 213 µm above the surface of the bottom insert. We could interpolate to find the offset experienced by our hypothetical 800 µm fiber, but it turns out that in a 60° V-groove, the offset is equal to the outer diameter difference. So in our example, that means that the center of our fiber is going to sit 50 µm above the bottom insert surface, since it is 50 µm larger than the fiber that the bottom insert was designed for (800 - 750 = 50). - Holding blocks designed for fibers less than Ø1000 µm have vacuum holes, designed to aid in aligning small fiber within the groove, while bottom inserts for fibers of Ø1000 µm or larger do not have these holes. The fiber holding block can be used with a vacuum pump that provides a small holding force via these holes, keeping small fibers in place as the clamps are lowered. Inserts with vacuum holes are indicated by a superscript "d" in the table below.
Top Insert Item # | VHA00a | VHA05b | VHA10b | VHA15b | VHA20b | VHA25 | VHA30 | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Accepted Diameter (Nominal) | ≤320 µm | 400 µm | 500 µm | 750 µm | 1000 µm | 1250 µm | 1500 µm | 1750 µm | 2000 µm | 2250 µm | 2500 µm | 3000 µm | |
Bottom Insert Item # |
Accepted Diameter (Nominal) |
Min / Max Accepted Fiber Diameter (µm) Min / Max Fiber Offset (µm) |
|||||||||||
VHD080c | 80 µm | 57 / 100 -23 / 21 |
- | - | - | - | - | - | - | - | - | - | - |
VHD125c | 125 µm | 88 / 161 -37 / 36 |
- | - | - | - | - | - | - | - | - | - | - |
VHD160c or VHF160c,d |
160 µm | 112 / 208 -49 / 48 |
- | - | - | - | - | - | - | - | - | - | - |
VHF250c or VHF250c,d |
250 µm | 177 / 320 -73 / 69 |
275 / 323 23 / 74 |
- | - | - | - | - | - | - | - | - | - |
VHD400c or VHF400c,d |
400 µm | 279 / 519 -122 / 119 |
377 / 517 -23 / 117 |
410 / 519 -9 / 119 |
- | - | - | - | - | - | - | - | - |
VHD500c or VHF500c,d |
500 µm | 346 / 592 -153 / 93 |
447 / 647 -53 / 147 |
476 / 711 -24 / 211 |
560 / 795 61 / 296 |
- | - | - | - | - | - | - | - |
VHD750c or VHF750c,d |
750 µm | 516 / 759 -234 / 9 |
617 / 970 -132 / 221 |
643 / 878 -107 / 128 |
728 / 963 -23 / 213 |
812 / 1047 62 / 297 |
- | - | - | - | - | - | - |
VHE10b | 1000 µm | - | - | 773 / 1008 -172 / 63 |
858 / 1093 -88 / 147 |
943 / 1178 -3 / 232 |
1036 / 1271 90 / 325 |
- | - | - | - | - | - |
1250 µm | - | - | - | 1034 / 1269 -176 / 59 |
1119 / 1354 -91 / 144 |
1212 / 1447 2 / 237 |
1288 / 1523 78 / 313 |
- | - | - | - | - | |
VHE15b | 1500 µm | - | - | - | - | 1280 / 1515 -172 / 63 |
1373 / 1608 -79 / 156 |
1449 / 1684 -2 / 233 |
1534 / 1769 82 / 314 |
- | - | - | - |
1750 µm | - | - | - | - | - | 1534 / 1770 -159 / 76 |
1611 / 1846 -83 / 152 |
1695 / 1930 2 / 237 |
1772 / 2007 78 / 313 |
- | - | - | |
VHE20b | 2000 µm | - | - | - | - | - | - | 1787 / 2022 -171 / 64 |
1871 / 2106 -86 / 149 |
1947 / 2183 -10 / 225 |
2032 / 2267 74 / 309 |
- | - |
2250 µm | - | - | - | - | - | - | - | 2033 / 2268 -167 / 68 |
2109 / 2344 -91 / 144 |
2193 / 2429 -6 / 229 |
2278 / 2513 78 / 313 |
- | |
VHE25 | 2500 µm | - | - | - | - | - | - | - | - | 2270 / 2505 -172 / 64 |
2355 / 2590 -87 / 148 |
2439 / 2675 -2 / 233 |
2609 / 2844 167 / 402 |
VHE30 | 3000 µm | - | - | - | - | - | - | - | - | - | 2692 / 2944 -256 / -4 |
2777 / 3029 -171 / 81 |
2946 / 3198 -2 / 250 |
Fiber Holder Insert Assembly and Installation
After you select the correct fiber inserts for your nominal fiber diameter, the fiber inserts need to be installed into the fiber holding block, as illustrated in the video below to the left using our Vytran processing stations. With the FHB2 holding block, the bottom insert needs to be flush with the bare fiber side of the block for the vacuum holes to align. Standard fiber inserts are meant to remain installed in the block when processing fibers of the same size, while fiber transfer inserts are used to move a fiber from one block to another, or to a compatible Vytran machine for additional processing. Transfer inserts consist of a fiber holder bottom insert, fiber transfer clamp, and graphite V-groove that require assembly as illustrated in the video below to the right using a processing station. The steps are similar for the FHB2 holding block.
Posted Comments: | |
Lawrence Hughes
 (posted 2023-12-01 12:29:14.557) I am using a FHB2 for fiber process development and would like to install an LED into the insert (as is done on the splicer).
Is it possible to purchase the led with silicone pad for use with inserts not used in splicers?
Can you quote 5 pieces if they are available?
THanks, cdolbashian
 (posted 2023-12-15 09:19:44.0) Thank you for reaching out to us with this feedback. I have reached out to you in order to clarify your inquiry and determine feasibility on our end. |
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Components
Included
- Fiber Holding Block
- 0.050" Hex Key
Must be Purchased Separately
- Fiber Holder Top Insert (One Required)
- Fiber Holder Bottom Insert (One Required)
Optional Accessories (Not Offered by Thorlabs)
- Vacuum Pump
- 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.
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Top Inserts | ||
---|---|---|
Item # | Side 1 Accepted Diameter (Min/Max) |
Side 2 Accepted Diameter (Min/Max) |
VHA00 | 57 µm / 759 µma | 275 µm / 970 µm |
VHA05 | 410 µm / 1008 µm | 560 µm / 1269 µm |
VHA10 | 812 µm / 1515 µm | 1036 µm / 1770 µm |
VHA15 | 1288 µm / 2022 µm | 1534 µm / 2268 µm |
VHA20 | 1772 µm / 2505 µm | 2032 µm / 2944 µm |
VHA25 | 2278 µm / 3029 µm | N/A |
VHA30 | 2609 µm / 3198 µm | N/A |
- 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 to the Right for Details)
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 above 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.
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Single-Fiber Bottom Insertsa | ||||
---|---|---|---|---|
Item # | Transfer Insert |
Side 1 Min/Max Accepted Diameter |
Side 2 Min/Max Accepted Diameter |
Vacuum Holes |
VHD080 | No | 57 µm / 100 µm | N/A | Yes |
VHD125 | No | 88 µm / 161 µm | ||
VHD160 | No | 112 µm / 208 µm | ||
VHF160 | Yesb | |||
VHD250 | No | 177 µm / 323 µm | ||
VHF250 | Yesb | |||
VHD400 | No | 279 µm / 519 µm | ||
VHF400 | Yesb | |||
VHD500 | No | 346 µm / 795 µm | ||
VHF500 | Yesb | |||
VHD750 | No | 516 µm / 1047 µm | ||
VHF750 | Yesb | |||
VHE10 | No | 773 µm / 1271 µm | 1034 µm / 1523 µm | No |
VHE15 | No | 1280 µm / 1769 µm | 1534 µm / 2007 µm | |
VHE20 | No | 1787 µm / 2267 µm | 2033 µm / 2513 µm | |
VHE25 | No | 2270 µm / 2844 µm | N/A | |
VHE30 | No | 2692 µm / 3198 µm | N/A |
- 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 to the Right)
- VHF Transfer Inserts are Used with VHT1 Transfer Clamp to Aid in Transferring a Fiber with ≤Ø1.047 mm Coating between Compatible Vytran Systems
- 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 the table to the right). 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 the table to the right. For information on how to assemble transfer inserts, see the Fiber Holder Inserts tab.
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Graphite V-Grooves | ||
---|---|---|
Item # | Accepted Diametera (Min / Max) |
Groove Length |
VHG125 | 80 µm / 125 µm | 0.313" |
VHG125L | 80 µm / 125 µm | 0.594" |
VHG200 | 150 µm / 200 µm | 0.313" |
VHG250 | 200 µm / 250 µm | 0.313" |
VHG250L | 200 µm / 250 µm | 0.594" |
VHG300 | 250 µm / 300 µm | 0.313" |
VHG350 | 300 µm / 350 µm | 0.313" |
VHG400 | 350 µm / 400 µm | 0.313" |
VHG450 | 400 µm / 450 µm | 0.313" |
VHG500 | 450 µm / 500 µm | 0.313" |
VHG500L | 450 µm / 500 µm | 0.594" |
VHG550 | 500 µm / 550 µm | 0.313" |
- 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 the size table to the right 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.
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Multi-Fiber Bottom Inserts | |||
---|---|---|---|
Item # | Type (Click for Drawing) |
Accepted Diameters | Recommended Top Inserta |
VHD125S | Side-by-Side | 125 µm / 125 µm | VHA00 |
VHD250S | Side-by-Side | 250 µm / 250 µm | |
VHD320S | Side-by-Side | 320 µm / 320 µm | |
VHD250V | Double-V-Slot | 250 µm / 250 µm | |
VHD320V | Double-V-Slot | 320 µm / 320 µm | |
VHD165C | Double-V-Slot w/ Pins | 165 µm / 165 µm | |
VHD250C | Double-V-Slot w/ Pins | 250 µm / 250 µm | |
VHD320C | Double-V-Slot w/ Pins | 320 µm / 320 µm | |
VHD550C | Double-V Slot w/ Pins | 550 µm / 550 µm | |
VHS250250 | Triple-V-Slot | 250 µm / 250 µm / 250 µm | |
VHS250400 | Triple-V-Slot | 250 µm / 400 µm / 250 µm | |
VHS250500 | Triple-V-Slot | 250 µm / 500 µm / 250 µm | |
VHS300350 | Triple-V-Slot | 300 µm / 350 µm / 300 µm | |
VHS320400 | Triple-V-Slot | 300 µm / 400 µm / 300 µm | |
VHS320550 | Triple-V-Slot | 320 µm / 550 µm / 320 µm | VHA05 |
![](https://www.thorlabs.us/images/tabimages/Multi-Fiber_Inserts_A3-150.jpg)
Click to Enlarge
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 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 photo to the left). 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 the table to the right. 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.