Direct answer
Coupling ratio describes how output power is divided; it does not independently establish low loss. Review branch insertion loss, excess loss and the definition of uniformity alongside ports, wavelength range and connector inclusion. A sample report explains fields but cannot replace delivery evidence for the actual lot or serial number.
Align denominators and ports
Corning's definitions normalize ratio to summed outputs and compare input with summed outputs for excess loss. Branch insertion loss includes power division. A 50/50 label alone therefore cannot establish how much input power reaches the outputs.
Use this guide to review passive-coupler and monitoring-branch reports. Draw the ports before reading values; results for another input direction or band may not address the requirement.
| Metric | Review | Do not infer |
|---|---|---|
| Coupling ratio | Output allocation | Lossless transmission |
| Branch insertion loss | Input-to-branch loss | Equal results for all branches |
| Excess loss | Input versus summed outputs | Each branch's allocation |
| Uniformity | Range and difference definition | Equal output powers |
| Measurement scope | Ports and connector inclusion | Identical finished constructions |
A balanced ratio can coexist with loss
For an original arithmetic example, assume 1 mW input and two outputs of 0.45 mW each. Each represents 50% of summed output, but total output is 0.9 mW. This illustrates the denominator only, not a measured device, allowed loss or quotation value.
When comparing two 50/50 quotations, check their loss definitions, bands and delivered construction. Connector-excluded data and connectorized-assembly data need aligned boundaries before comparing the smaller number.
Require an explicit uniformity definition
The Thorlabs sample report uses uniformity for insertion-loss variation across bandwidth; Corning compares insertion loss between output ports. Identical names cover different comparisons. Retain each definition and specify the range and decision rule required by the project.
Retain the original English field with its translated explanation. Where names overlap, obtain the calculation definition instead of inferring denominators or statistical scope from words such as uniformity, balance or consistency.
Separate specification bandwidth from plot extent
The sample distinguishes specified bandwidth from extended plots and states room-temperature, designated-input and connector-excluded conditions. Marked SAMPLE, it cannot establish conformity of a project sample or shipment.
Retain complete pages rather than cropping the flattest trace segment. A wavelength appearing on a plot does not itself establish a guaranteed operating band; use the agreed specification and conditions.
| Record | Retain | Resolve differences |
|---|---|---|
| Port map | Input, outputs, fiber IDs | Align input direction |
| Metric table | Original name, definition, units | Establish denominator/range |
| Plots and specification | Plot span and approved band | Do not extend guarantees |
| Test conditions | Temperature, connectors, planes | Check finished scope |
| Traceability | Part, revision, delivery identifier | Separate samples from shipments |
Define delivered construction in the RFQ
Provide port topology, operating band, allocation needs and interface drawing, then request a verification method for each required property. Agree limits and records rather than filling them from a generic sample.
For multifiber assemblies, map the relevant fibers to device ports. One coupler report cannot cover every trunk fiber and connection automatically. Related pages support test connections and system-loss review without asserting a confirmed ARRANEX coupler offering.
Procurement FAQ
- Does correct ratio prove low loss? Review loss and measurement boundary separately.
- Is uniformity output-to-output difference? Use the report's explicit definition.
- Can an extended plot establish operating bandwidth? Check the approved specification.
- Can a sample report serve as shipment evidence? Obtain records matching the actual delivery identifiers.
- What belongs in the RFQ? Port map, band, allocation, finished interfaces and reporting scope.
Related products and reading
- Test connection reference cords
- Passive TAP path-loss budgeting
- Optical splitting versus multifiber fanout
- Insertion-loss and return-loss guide
Related pages support requirements review. Materials, service conditions, performance and delivery scope depend on mutually confirmed specifications.
Contact an engineer with drawings and validation requirements
Sources and review date
Reviewed on 2026-10-19. Source dates remain separate from the review date. Manufacturer examples explain terminology; procurement tables are editorial recommendations, not ARRANEX specifications or certifications.
Sources checked: 2026-10-19