Photo: Damage in fiber-optic phase modulator

Result of electrical breakdown in fiber-optic phase modulator

This is a part of waveguide after electrical breakdown in a travelling-wave 8GHz phase modulator (JDS Uniphase UTP PM-130-080, now discontinued). The gold electrodes and lithium niobate substrate melted and obviously partially evaporated in the arc. Voltage was supplied to the left side of the thin electrode; breakdown occurred at 20 to 30 V, probably due to contamination left in the modulator after we had to open its hermetic package. The surface optical waveguide (can't be seen) made in the crystal somewhere near the electrode gap also got damaged: optical attenuation rose by 10dB.
This panoramic image was composed of three photographs taken through a microscope. Just to clarify: this is not the actual explosion, this is what's left after it (permanent debris).

A general view of the open modulator (see left image) is available as 800x1600 JPEG (300dpi) or 3200x6400 JPEG (1200dpi; 3MB). This is a flatbed scan: the device was placed top side down on the scanner glass, just as a paper document.

These pictures from Quantum hacking lab gallery illustrate New Eavesdropping Strategies in Quantum Cryptography page, Optic, Electrooptic and Fiber-Optic Components directory and are included in Picture Collection (ref. nr. a66-30comp) on Photo Pages

Tech info on top microphotograph: Bausch & Lomb Micro Zoom microscope (zoomed out), Bausch & Lomb Industrial 25x 0.31NA objective, Bausch & Lomb 10x W.F. ocular; built-in halogen lamp illuminator set at max. brightness; microscope focused with eye looking through its objective. Fujichrome Sensia II 100 film, Canon EOS 3, EF 50mm 1:1.4 USM lens, 80B filter stuck to the microscope ocular as close as possible, lens set at focusing scale infinity, lens centered relative to the ocular by image of its closed-down aperture; f/1.4 (actual aperture seemed to be limited by microscope) 1.3sec, spot metering: gold(?) deposit ("flame") +1, (green) surface of lithium niobate crystal 0; viewfinder image was grainy and poor; tripod. Taken on July 19, 2000. Scanned on Nikon LS30 scanner.

Tech info on the general view: Agfa DuoScan T1200 flatbed scanner, 1200dpi, full density range, no post-scan adjustments.

Vadim Makarov