22 checks. Every module.
“Every optic is tested” covers a 1E-12 bit error rate at 70 °C, and it covers plugging it in to see whether the light comes on. Here is exactly what ours means — including which checks run on a sample rather than on everything.
The headline numbers
What “tested” means here
This is a production-line quality control process. It happens where the module is built, on the line that builds it, using the test equipment on that line. It is not a second round of testing performed on receipt in a warehouse, and we are not going to imply that it is.
It matters because “we test every optic” is a claim a lot of suppliers make and mean very different things by — ranging from a full optical performance suite down to confirming the module powers up. What follows is a specific documented process with named equipment, written pass criteria, sampling proportions, and a defined route for anything that fails.
Every module is performance tested. A proportion are additionally stress tested at high temperature.
Those are two different sentences, and most testing pages only publish the first one. The coverage table further down this page says exactly which checks are which.
The process is documented for the 40G and 100G module lines, which is where the detail below comes from.
All 22 steps, in order
Grouped into five stages. Steps marked Key process are flagged as such in the quality control chart itself — they are the four where a mistake is hardest to catch later.
Materials, firmware and identity
- 1 · Materials preparation Check the materials correspond to the bill of materials. Run at the start of every shift and after any model change or machine adjustment.
- 2 · Firmware burningKey process
Select and burn the corresponding firmware for the part being built.
Equipment: PC, burning board, power supply, turnover tray, anti-static wrist strap
- 3 · Firmware verification A separate step on a dedicated firmware detection system, confirming the correct firmware was actually written. Not the same as burning it.
- 4 · Serial number written The corresponding serial number is written to the module.
Build and assembly
- 5 · Cable installation and adhesive dispensingKey process
The written criteria are specific: the adhesive must be properly covered, must not
overflow, and the cure is 30 seconds of irradiation.
Equipment: dispensing machine, dispensing fixture, turnover tray, anti-static wrist strap
- 6 · Initial optical engine power testKey process The optical engine's power output must fall within range before it goes any further — so a bad engine is caught before anyone builds a housing around it.
- 7 · Housing and optical engine assembly
The engine seats on the base with the right tension, the pull ring is checked for normal
opening and closing, the position of the thermal conductive adhesive is
checked, and the appearance is inspected.
Why it matters: the thermal adhesive is the difference between a module that dissipates heat into its cage as designed and one that runs hot in a dense switch — a fault that does not show on a bench and does show up in a warm rack months later.
Optical performance
- 8 · Eye diagram debugging
Extinction ratio and the other optical parameters must meet requirements. Judged by the
test software rather than by eye.
Equipment: direct current supply, BERT, thermometer, fixed light source, test board, optical power meter, optical attenuator, fibre patch cord
- 9 · Module debuggingKey process
The parameters watched here are P0 (output power), LOS (loss of signal),
Icc (supply current) and DDM calibration.
Why it matters: DDM is how the module reports its own power, bias current and temperature back to your switch — the numbers you read in the interface table. An uncalibrated module reporting nonsense diagnostics is worse than one reporting nothing, because it sends you looking in the wrong place.
- 10 · Initial performance testing
70 °C, a bit error rate of 1E-12, zero bit errors, with P0,
extinction ratio and DDM monitoring within requirement.
Why that number: 1E-12 is the bit error ratio objective IEEE 802.3 sets for Ethernet PHYs — the module is held to the same figure the standard holds the link to.
- 11 · Fibre transmission testing At 25 °C for 60 seconds, again at 1E-12 with zero bit errors, with P0, extinction ratio and DDM monitored throughout.
- 12 · High-temperature testing Runs on a 5% sample, not on every module. Said plainly because it is the kind of thing that usually gets rounded up to “every”.
Cleaning, coding and the switch test
- 13 · End face cleaning and inspection
Under a microscope fibre end-face inspector.
Equipment: microscope end-face inspector, end face cleaner, dust-free paper, alcohol, cotton swabs · Why it matters: contamination on an end face is the single most common cause of loss on an optical link, and it looks like a marginal link at the far end rather than a dirty connector.
- 14 · Appearance cleaning and inspection
- 15 · Labelling The label must be undamaged and attached within the specified range.
- 16 · EEPROM programming
The module's code file is written with the specific requirements for the order.
Equipment: PC, card reader for EEPROM programming, power supply, barcode scanning gun
- 17 · EEPROM and serial number verification
Reads back manufacturer, part number, serial number, date, threshold, PAGE0 and
PAGE1 and confirms each matches the order.
Why it matters: this is the coding step, and it decides whether the optic works in your switch. A switch reads that EEPROM to identify the module, and on many platforms uses what it reads to choose a link-layer setting such as FEC mode. Get it wrong and the link stays down while logging nothing useful about the transceiver.
- 18 · Switch testing The module goes into an actual switch. Checks are module locking and unlocking, link establishment, and EEPROM information, judged by the switch itself.
QA, packaging and warehouse entry
- 19 · QA appearance sampling inspection By the quality department rather than by production.
- 20 · Packaging and labelling Vacuum packaging, appearance check, label and quantity verification.
- 21 · Finished appearance and outer box QA inspection Packing appearance, model, standards, label information and quantity, on a C=0 acceptance basis — the sample is rejected on a single defect.
- 22 · Finished goods storage Order quantity, product information and packaging integrity, checked on every box.
And when something fails, at any of the 22 steps, the route is the same.
The unit is isolated and identified, a nonconforming product disposal form is raised, and a corrective and preventive action report follows. Failures are not simply set aside — they generate a record, which is what makes a recurring fault visible rather than a series of unrelated one-offs.
Which checks run on everything, and which run on a sample
This is the question to ask any optics supplier, so here is our answer without being asked.
| Check | Coverage |
|---|---|
| Firmware verification | 100% |
| Eye diagram and extinction ratio | 100% |
| Performance test — 70 °C, 1E-12, zero errors | 100% |
| Fibre transmission — 60 seconds at 25 °C | 100% |
| End face inspected under a microscope | 100% |
| Appearance cleaning and inspection | 100% |
| EEPROM programming and verification | 100% |
| Tested in a live switch | 100% |
| Packaging and warehouse-entry checks | 100% |
| High-temperature stress test | 5% sample |
| QA appearance inspection | 5–20% |
| Outer box inspection | C=0 sampling |
On top of that, eight in-process stations — firmware burning, serial writing, adhesive dispensing, initial power testing, housing assembly, module debugging, labelling and QA appearance — carry a 5–20% independent quality inspection twice a day, in addition to the 100% operator check at each station.
What we do not claim
Being specific about what is done means being equally specific about what is not.
We do not thermal-cycle every module
High-temperature testing is a 5% sample. Every module is tested at 70 °C and at 25 °C, which is not the same as cycling it between them.
We do not test to −40 °C
The documented temperatures in this process are 70 °C and 25 °C. Modules specified for industrial temperature ranges are a different specification and should be ordered as one.
We do not re-test on receipt
This is production-line quality control at the point of manufacture, not a second pass in a warehouse.
We do not publish an MTBF figure
We do not have one derived from our own field data, and quoting somebody else's would be meaningless.
Six questions to ask any optics supplier
These separate a real process from a claim. Ask them of us, and ask them of whoever else you are quoting.
Anyone with a real process can answer this immediately, with numbers.
“We test for errors” is not an answer. 1E-12 with zero errors at 70 °C is.
If it is not, every diagnostic reading you take from that module afterwards is decoration.
Cheap to do, expensive to skip, and invisible until it is a fault.
Coding faults do not show up any other way.
If the answer is not “isolated, recorded, and the failure analysed”, the process has no feedback loop.
Testing tells you it was built right
It does not tell you whether it is the right module. That is a coding and specification question, and it is answered before you order rather than after.
