Teledyne LeCroy WaveExpert 9000_NRO9000_SDA100G Getting Started Manual - Manual (Page 32)

30 ISSUED: September 2005 WE-GS-E Rev A
Connector Torque
In order to maintain bandwidth performance and minimize loss, connections to the instrument
modules should be torqued to the appropriate tightness. The connectors all have standard 3/8
inch nuts on them and should be torqued to 8 in-lbs. using an appropriate torque wrench. The
100 GHz module has a unique connector that requires a smaller torque value of 4 in.-lbs. This
module is supplied with the appropriate torque wrench.
Optical Modules
Several optical modules are also available for use with the WaveExpert mainframe. The modules
are outlined in the table below. Optical modules are available in single-mode and multimode
configurations. The single-mode modules are designed to operate over wavelengths in the 1280
to 1620 nm range, while the multimode module covers the 750 to 1620 nm range. Single-mode
and multimode fibers are characterized by different diameters. Multimode fiber, as its name
implies, allows many “modes” or group velocities to propagate, while single-mode allows only
one. The diameter of multi-mode fiber is much larger than that of single-mode fiber (50 to 62.5 nm
vs. 9.5 nm) so connecting a multimode fiber to a single-mode one will result in a large amount of
signal attenuation caused by the difference in area of the connector faces. Since the energy in a
multimode signal is spread out into the many modes propagating in the fiber, at the boundary with
the single-mode fiber only one of these modes will pass through.
Module Wavelength Range Fiber Type Fiber Diameter
SO50 1280-1620 nm Single mode 10 µm
SO25 1280-1620 nm Single mode 10 µm
SO10 750-1650 nm Multimode 62.5 µm
Single-mode fiber has a narrow core diameter that allows only one mode to propagate. This type of fiber is very
low loss, so it is the choice for long-haul communications.
Multimode fiber has a much wider core diameter that allows many modes to propagate. This type of fiber has
higher loss, but is less costly, is easier to work with, and is the choice for LAN and other short-haul applications.