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CO₂ Laser Glass Processing System
Splicing of Ø20 µm Core / Ø400 µm Cladding Passive Fiber to Active Fiber
Fiber Holder Bottom Transfer Insert
Transfer Clamp with Magnetic Lid
Glass Processor Workstations, Inserts, and Accessories All Sold Separately
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When splicing, the laser forms an annular beam shape that uniformly heats the fiber ends and then the two fibers are carefully pushed together.
The GPX4000LZ offers the most advanced glass shaping features of our Vytran® fiber processing workstations. Unlike our other glass processors, the furnace tower on the GPX4000LZ uses two user-exchangeable heat sources. The primary 40 W CO2 laser heat source enables the fabrication of advanced features such as large end caps (fuse directly to end caps up to Ø5 mm; see examples below) or complex terminations. It also does not require purge gas or consumable filaments, which greatly reduces the maintenance needed. The laser optical head can be swapped for a standard filament fusion furnace that allows the use of existing filament-based recipes on the GPX4000LZ. The combination of these two modes provides users the flexibility to develop fabrication recipes that best suit their application. Fully-automated XY and rotational alignment using our True Core Imaging technology is compatible with both heating modes. The glass processing workstation, computer with process development and operation software, and power supply are integrated into a rolling cart for easy movement in the workspace.
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Examples of end-capped fibers: a) Ø4.0 mm silica end cap fused onto a Ø250 µm fiber and b) Ø1.25 mm silica end cap fused onto a Ø125 µm fiber.
The CO2 laser heat source outputs a 40 W (CW) beam that uniformly and directly heats the fiber end (see image to the right) leaving no residue or contamination on the fiber surface. High-performance axicon lenses are used to shape the laser beam into an annular (i.e., doughnut) beam shape. Two optical heads for focusing the laser beam are included with the workstation; the splice head is optimized for splicing and tapering processes, while the end-cap head is designed for heating and fusing large end caps onto the ends of optical fibers.
The filament-based heat source, which uses either a graphite or iridium omega-shaped filament, can accommodate a wide range of fiber cladding diameters and specialty fiber types using the same system. Precise control over fiber position and orientation enables a number of advanced fiber processing applications from low-loss splicing in dissimilar fibers to the creation of adiabatic fiber tapers, fiber terminations, or fused fiber couplers. Three filaments are included with the GPX4000LZ and additional or replacement filaments can be purchased separately below.
True Core Imaging
Options and Accessories
Several optional add-ons are available for these systems to enable specialized applications. Multi-fiber holder bottom inserts are used when fabricating couplers or combiners and are designed to hold two or three fibers in close proximity during heating. The GPXLZWCS Liquid Cooling System helps cool the furnace assembly during extended heating using the filament heating mode and is recommended for customers interested in creating long fiber tapers.
Fiber Holder Inserts Selection Guide (Top Inserts and Standard or Transfer Bottom Inserts)
Fiber Holder Inserts, which are designed to hold various sized fibers within the glass processors, 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, as the fiber outer diameter clamped by the left and right holding blocks may not be the same. At least two top inserts and two bottom inserts are required to operate the glass processor. 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. This may require different sets of fiber holder inserts to be used in the left and right holding blocks. In this case, it is important to minimize the difference in the offsets introduced by the left and right sets of inserts when attempting to produce high-quality splices.
Each V-groove can accommodate a range of fiber sizes.
Fiber Insert Selection Chart
Example Splice, Taper, and End-Cap Files
Each glass processor workstation is shipped with a PC and monitor pre-installed with the GUI software for operating the glass processor. An abbreviated library of splice process files, listed to the right, is included for common splicing and tapering procedures. The GUI and splice library software enables users to create their own splice files for new processes or to customize existing files as necessary. Please contact Tech Support for inquiries regarding your specific application.
The sections below illustrate several fiber splicing and tapering applications that can be programmed through the software GUI.
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Figure 1. Screenshot of PM Fiber Alignment Configuration Window
The end-view alignment process is initiated by pulling the fibers back so that an end-view mirror can be inserted between two fiber end faces. An LED illuminates the fiber cladding, allowing the software to image the fiber end. Then, the image of the fiber end face is displayed and used to automatically align the cores of the two fibers. PM alignment parameters can be set for each fiber type as shown Figure 1 to the right. This window consists of four parameters: diameter (fiber cladding), fiber type, and two PM geometry parameters for both the left and right fiber. If these parameters are not known, it is possible to directly measure them using the displayed image of the fiber end face.
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Figure 2. Screenshot of Taper Geometry Customization Window
Fiber Taper Customization
During the tapering process, three different regions are created. Initially, the fiber is elongated and tapered under constant heating creating the "down taper" region where the fiber diameter is decreasing. Once the fiber has been tapered down to a desired diameter, a constant rate of elongation is applied so that there is a region with a reduced, but constant diameter, known as the "waist" of the fiber. Finally, the pulling force on the fiber is reduced until finally it is no longer elongating, creating the “up taper.” The filament temperature and pull velocities are controlled to achieve the desired geometry of the fiber.
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Figure 3. Screenshot of Tension Monitor and Control System
Tension Monitoring System
As an example, a standard Ø400 to Ø200 µm taper should be pre-tensioned to approximately 20 g. The desired pre-tension is applied by pulling the fiber in fine steps using one of the fiber holding blocks. During the taper process, the fiber tension is monitored to help adjust the tension parameters and improve the resulting taper. For example, if the tension drops to 0 or negative values, the heating should be decreased because the glass has been softened too much. Conversely, if the tension increases beyond a given set point, heating should be increased because the fiber has not been sufficiently softened.
Laser Safety and Classification
Safe practices and proper usage of safety equipment should be taken into consideration when operating lasers. The eye is susceptible to injury, even from very low levels of laser light. Thorlabs offers a range of laser safety accessories that can be used to reduce the risk of accidents or injuries. Laser emission in the visible and near infrared spectral ranges has the greatest potential for retinal injury, as the cornea and lens are transparent to those wavelengths, and the lens can focus the laser energy onto the retina.
Safe Practices and Light Safety Accessories
Lasers are categorized into different classes according to their ability to cause eye and other damage. The International Electrotechnical Commission (IEC) is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC document 60825-1 outlines the safety of laser products. A description of each class of laser is given below:
Must be Purchased Separately
Optional Accessories and Replacement Items
The GPX4000LZ CO2 Laser Glass Processor Workstation integrates the furnace tower, fiber holding blocks, computer with operation and process development software, and other operational equipment into an easy-to-use rolling cart that can be positioned anywhere in the lab.
This workstation features automatic XY and rotational alignment of the fiber and is specially designed for processing polarization-maintaining fibers as well as specialty fibers with microstructured cores using the True Core Imaging Technology. Precision fiber handlers can translate and position a fiber in XY with a resolution of 0.25 µm and rotate a fiber up to 190° with a resolution of 0.02°. The included fiber holders can translate along the fiber axis up to 105 mm or 180 mm using the CO2 laser or filament heating modes, respectively. This allows the furnace to heat large portions of the input fiber(s) and is ideal for many applications including thermally diffusing core dopants to achieve low-loss splices between highly dissimilar fibers or for fabricating long adiabatic fiber tapers. The fiber holding blocks can also pull vacuum through fiber holder inserts with vacuum holes to help secure the fiber within the insert.
The workstation includes the fiber holders, optical heads, furnace tower, CCD camera for imaging, PC and monitor pre-installed with the control software, and mirror tower for side- and end-view imaging. For operating in the filament heating mode, the workstation is fitted with a high-purity PTFE gas line and a gas regulator equipped with a CGA-580 output port; a DIN 477 Number 6 output port connector is also included. Replacement filaments can be purchased separately below.
Top and bottom inserts for the fiber holders, both of which are required to operate the glass processor workstation, can be purchased separately below. Optional multi-fiber holder bottom inserts for making couplers or combiners are also available below. Customers interested in splicing end caps can purchase end-cap holders that are compatible with the fiber holding blocks used in the glass processor workstation.
Installation and training by one of our application engineers is recommended for this system; please contact Tech Support for more details.
Fiber Holder Inserts, which consist of one top insert and either a bottom or transfer insert, are placed in the fiber holding blocks of the optical glass processor to secure the fiber during splicing or tapering. The inserts clamp the cladding, buffer, or coating of the fiber and can accommodate outer diameters of up to 3.198 mm. Please refer to the Fiber Holder Insert tab for more information on pairing the top and bottom inserts sold here.
Two types of top inserts are compatible with the GPX4000LZ. The VHA standard top inserts come in single-sided and dual-sided versions. These standard inserts can also be used in the Automated Glass Processors, LDC401 Series of Fiber Cleavers, FPS300 Stripping and Cleaning Station, and LFS4100 Splicing System. The VHB00 and VHB05 top inserts feature an indent for LED illumination from the automated glass processor workstations and are necessary for end-view imaging and alignment of the cores of polarization-maintaining and microstructured specialty fibers.
Fiber Holder Inserts, which consist of one top insert and a bottom insert, are placed in the fiber holding blocks of the optical glass processor to secure the fiber during splicing or tapering. Bottom inserts are magnetically held within the fiber holding blocks of the glass processors and other compatible systems. The V-groove machined into the bottom inserts ensures the fiber is centered within the fiber holder; inserts with different V-groove sizes are available (see the Fiber Holder Insert tab for more information on pairing top and bottom standard or transfer inserts). Vacuum holes at the bottom of the transfer inserts are used for holding and aligning small fibers within the V-groove.
Three types of bottom inserts are compatible with the glass processors: transfer bottom inserts, standard bottom inserts, and multi-fiber bottom inserts (sold further below). Transfer bottom inserts (indicated with Item #'s starting with VHF) allow for a single fiber to be transferred between the LDC401 Series of Fiber Cleavers, FPS300 Stripping and Cleaning Station, and the GPX4000LZ CO2 Laser Glass Processor with minimal loss of alignment. For example, a fiber can be placed in a transfer insert and cleaved using the LDC401 cleaver, then the entire transfer insert can be placed in the LFS4100 Splicing System for splicing. This process works because the transfer inserts are precisely located within each Vytran system, and the VHT1 Transfer Clamp (sold directly below) prevents axial movement of the fiber during transport. Transfer inserts are equipped with vacuum holes that provide a small suction force to hold the fiber in place. All of these transfer inserts require the VHT1 Transfer Clamp (sold below); transfer inserts for fiber outer diameters ≤550 µm also require a Graphite V-Groove (sold below).
Standard Fiber Holder Bottom Inserts (indicated by Item #'s starting with VHE) can be used with fibers with large-diameter fibers. These inserts come in single-sided and dual-sided versions. The standard bottom inserts can also be used in the LDC401 Series of Fiber Cleavers, FPS300 Stripping and Cleaning Station, Automated Glass Processors and LFS4100 Splicing System. Unlike transfer inserts, alignment of the fibers will not be maintained when these inserts are transferred between systems.
These Transfer Clamps and V-Grooves are used with the VHF Transfer Bottom Inserts sold directly above to move a single fiber between 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.
For fibers with diameters ≤550 µm, a graphite V-groove must be purchased to support the fiber when splicing (please see the size table to the right for more information). The 1.094" long V-grooves are designed for use only with the GPX4000LZ CO2 laser heating mode, while the 0.313" and 0.594" long V-grooves are used with the filament heating mode. The graphite V-grooves are secured by tightening the two setscrews in the transfer insert.
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The VHD320P features adjustment pins that are used to bring two fibers into very close proximity for splicing.
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 VHD320P insert additionally features offset adjustment pins that are used to bring the two fibers in close contact during splicing (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 alllow a signal fiber to be fused with two pump fibers.
These bottom inserts are magnetically held within the fiber holding blocks of the glass processors and other compatible systems. 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.
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An Ø8 mm end cap with a Ø1 mm lead-in is secured within the front clamp of the ECH8C.
These holders secure and position end caps in the glass processor workstation during the fusion process. Holders for end caps with outer diameters ranging from 1.8 mm to 8.0 mm are available. Clamp- and lid-style.
Holders with Vacuum Suction
Holders with Flexure Clamp
Holders with Magnetic Lid
The GPXLZWCS Liquid Cooling System is an optional add-on for our GPX4000LZ Glass Processor that helps keep the furnace tower cooled during extended heating operations when using the filament heating mode. It is highly recommended for customers interested in fiber tapering, mode adapter, or fiber termination applications. If the GPXLZWCS is ordered at the same time as the GPX4000LZ Glass Processor Workstation, it can be installed at the factory prior to shipping.
The GPXLZWCS has a 157 mL reservoir to cycle high-performance liquid coolant (700 mL bottle of coolant included) at flow rates of up to 4 L/min with a cooling capacity of 590 W at 25 °C ambient temperature; click here for an MSDS safety sheet. Tubing and fittings for connecting to the GPX4000LZ are included. The cooling system can be powered either through a 12 VDC Molex Connector (via the included computer slot adapter) or externally using the included 110/120 VAC power adapter.
Filament Assemblies contain a graphite or iridium omega-shaped resistive heater element encased within a protective shroud. The filaments sold here are compatible with the automated glass processors; those indicated in the table to the right as splice filaments are also compatible with the LFS4100 Splicing System and other GPX Series Automated Glass Processors.
A selection of six graphite and three iridium filament assemblies for fibers with claddings up to Ø1800 µm are available. Graphite filaments are capable of achieving the high temperatures necessary for splicing or tapering large-diameter fibers while outgassing less than filaments made from other metals. Alternatively, iridium filaments heat fibers at slightly lower temperatures than graphite filaments, making these ideal for working with soft glass fibers. Although the heating lifetime of a filament is approximately 40 minutes, this can vary depending on a number of factors including argon quality, splice/taper duration, and fiber glass quality.
Filaments are optimized for splicing or tapering applications; this is not restrictive, however, as splice filaments can be used for tapering. Splice filaments have an opening in the top of the assembly body, while tapering filaments are closed off at the top to minimize exposure to contaminants. Different filament bodies are distinguished by the version number (e.g., V2, V6, T3) engraved on the assembly body.
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USC2 Ultrasonic Cleaner and USC2NVT Nest for Vytran Transfer Bottom Inserts
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The cleaning intensity and duration controls are located on the rear of the cleaner.
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Thorlabs' Vytran® USC2 Ultrasonic Fiber Cleaner is designed for volume processing of bare fiber. Adjustment knobs for cleaning intensity and cleaning duration allow the user to easily set repeatable cleaning parameters. The dunking jig offers adjustable immersion depth and is compatible with interchangeable fiber holder nests (each sold separately). A red LED indicates when the cleaning cycle is active. The 100 mL solvent tank is only suitable for use with acetone or isopropyl alcohol.
Tilting the dunking jig submerges the fiber in the tank and initiates the ultrasonic cleaning process. The ultrasonic agitation ceases after the chosen cleaning duration. The height of the fiber holder above the solvent tank can be changed over a 0.5" (12.7 mm) range using the knurled adjuster on the side of the dunking jig, visible in the photo above.
The knurled adjuster can also be reversed to disengage the bare fiber nest and switch it out for another fiber holder nest. Each cleaner is shipped with a bare fiber nest installed in the dunking jig. The USC2NVT Nest (sold separately) is designed for use with Vytran transfer bottom inserts. Accessories are available for the Vytran fiber nest to support a wider range of usage scenarios, including a clamp for standard bottom inserts and spacers for recessing inserts farther from the solvent tank. We also offer nests for Fujikura® and Fitel® fiber holders (each sold separately). Please see the complete product presentation for more information.