Every 800G and 1.6T transceiver leaving a production line has to be measured, often more than once and often at several temperatures. Test instruments are expensive, and connecting fibers by hand is slow and wears out connectors. An optical switch matrix solves both problems: it lets a few instruments serve many devices under test, and it changes the optical path in milliseconds under software control.
How a switch matrix is used on a test line
- Aging and burn-in tests in coherent module mass production, where many modules run for hours and are checked in turn.
- Multi-channel parallel screening, where one analyzer or BERT is shared across many device ports.
- High and low temperature reliability fixtures, where devices sit in a chamber and the switch routes each one to the instruments outside.
Some 800G and 1.6T transceiver manufacturers already buy N×M optical switches for this kind of production testing. Note that the switch is part of the test system; it is not a transceiver and does not change the data rate of the device under test.
Choosing the matrix size
N×M matrices are available from 4×4 up to 64×64. 32×32 is one of the most frequently shipped sizes because it matches a typical test rack, and 64×64 has shipped for larger lines. Size the matrix for the number of instrument ports (N) and device ports (M) you need at peak, plus spare ports for reference paths and calibration. For very small setups, compact MEMS cross-connects in 4×4 and 8×8 configurations are an option.
Specifications that matter
- Insertion loss: ≤2.6 dB at 32×32 and ≤3.0 dB at 64×64. Include it in your power budget so the instrument still sees enough signal.
- Switching time: under 20 ms, short enough that path changes do not dominate the test cycle.
- Wavelength range: single-mode 1260–1650 nm, or multimode 850 ±40 nm.
- Interfaces: LC/UPC optical ports, with RJ45 or RS232 control for test automation software.
- Form factor: an integrated 2U rack-mount unit.
Integration tips
Keep fiber lengths and connector counts identical on every path so that each device sees the same loss, and calibrate each path once with a reference. Drive the switch from the same software that runs the instruments, so that every measurement is logged together with the path it used. If repeatability and polarization behavior matter for your measurement, tell us the test you run and we will confirm the relevant figures.