Thermal and Mechanical Tests of Loose-tube and Military Tactical
Fiber-optic Cables

A. Navarrini, R. Plambeck and E. Fields
Radio Astronomy Lab, University of California, Berkeley

We report on comparative tests of two types of fiber-optic cables,
a loose-tube currently in use at BIMA, and a much more flexible
tight-buffer military tactical one. A 1310 nm signal AM modulated
at 3 GHz was sent through two fibers within the same cable and the
phase and the phase difference variations were monitored when:
1) cycling the temperature of the cables in a thermal chamber;
2) moving or bending the cables. The measurements show that the
loose-tube cables are largely to be preferred for their lower
differential phase change between parallel fibers caused by
temperature variation and mechanical stresses.