Fiber Sensing

MEMS optical switches — the multiplexing engine. Our 1×N / M×N MEMS switches scale to 128 channels with 10⁹-cycle durability and ±0.05 dB repeatability: at one poll per channel per minute, that is decades of duty with a channel-to-channel loss that never drifts enough to fake an event. The repeatability figure is the whole game — an OTDR judges a cable by comparing one scan against the next, so the switch must re-couple to the same loss on every single actuation. Typical insertion loss of 1.0 dB keeps the power budget intact. PM versions hold polarization for coherent φ-OTDR, and software-defined matrix switches serve multi-instrument test labs.

Circulators — one fiber, both directions. At the interrogator front end, a 3-port circulator steers the launch pulse into the sensing fiber and routes the weak backscatter to the receiver. OTDR is a listed application of our standard and mini circulators — isolation to 40 dB and return loss to 50 dB keep the launch pulse out of the detector, and the mini package (Φ ≤ 3.0 × L ≤ 25 mm) is what fits the front end into an SFP-sized module. For multi-channel interrogators, the 8-in-1 arrayed circulator packs eight independent circulators into an 82 × 45 × 11.5 mm package.

The architecture lives or dies on the baseline. A polling system flags trouble by differencing scans, so every link in the front end must contribute no drift of its own: channel crosstalk of ≥ 40 dB keeps a neighboring fiber's reflection from masquerading as an event, directivity of ≥ 50 dB stops the launch pulse leaking backward into the source, and eight arrayed circulators share one thermal environment instead of drifting eight different ways.

Monitoring hybrids & specialty switches. Tap-PD hybrids (ITPD / TAPD, 1–10% tap ratios, hermetically sealed detectors) supervise launch power in-line so the system knows its own baseline — the hermetic seal is the hard part, since a bare photodiode in a monitoring tap is a humidity failure waiting for the field. Where a polling scheme calls for extreme endurance or latching behavior, magneto-optical switches (>100 billion cycles, no moving mirror and therefore no wear-out curve) and mechanical 1×1 / 1×2 / 2×2 switches cover the special cases.

Qualified for the field. Every device is batch-proven and qualified to Telcordia GR-1221 / GR-1073, with wide-temperature designs, custom wavelengths, fiber types and package outlines as routine practice for sensing programs.