Agilent Technologies 86120C, User Manual

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2-41
Making Measurements
Cleaning Connections for Accurate Measurements
• Is an instrument- grade connector with a precision core alignment re-
quired?
• Is rep eatability tolerance for reflection and loss imp ortant? Do your
specifications take repeatability uncertainty into account?
• Will a connector degrade the return loss too much, or will a fusion
splice be required? For example, many DFB lasers cannot operate with
reflections from connectors. Often as much as 90 dB isolation is needed.
Figure 2-3. Basic components of a connector.
Over the last few years, the FC/PC style connector has emerged as the
most p op ular connector for fiber- op tic ap p lications. While not the
highest performing connector, it represents a good compromise
between performance, reliability, and cost. If properly maintained and
cleaned, this connector can withstand many repeated connections.
However, many instrument sp ecifications require tighter tolerances
than most connectors, including the FC/PC style, can deliver. These
instruments cannot tolerate connectors with the large non- concentrici-
ties of the fiber common with ceramic style ferrules. When tighter
alignment is required, Agilent Technologies instruments typ ically use a
connector such as the Diamond HMS- 10, which has concentric toler-
ances within a few tenths of a micron. Agilent Technologies then uses
a sp ecial universal adap ter, which allows other cable typ es to mate
with this precision connector. See
Figure 2- 4 .