Principle of Operation of PriTel's Optical Clock Multiplier (see Applications Note)        Return to previous page

PriTel’s OCM uses Optical Time Domain Multiplexing to increase the
input pulse rate.  As shown in the schematic below, this is
accomplished by dividing the input pulse into two separate legs of a
Mach-Zehnder fiber interferometer.

One leg provides a variable pulse delay and amplitude equalization,
and the other leg, a fixed bit-pattern delay.  The two pulses are then
recombined, interleaving them to produce a repetition rate of two
times the input rate.

Schematic Diagram of PriTel's Optical Clock Multiplier, Model OCM-4

The OCM-4 unit has two cascaded stages of 2X.  The OCM-8 and
OCM-16 add additional stages of 2X and 4X to the OCM-4.

As shown in the schematic, there is an intermediate optical tap, and
the OCM-4 can be configured to provide 2X output pulses.  This
feature allows the researcher to align the experimental setup at lower
rates.  When the OCM is operating at 4X output, this 2X intermediate
port has unequalized pulses with a reduced input extinction ratio.

For Bit Error Rate Testing with PRBS, the input data pattern is
delayed by ½ the pattern length and then recombined to produce the
same PRBS at twice the repetition rate.  For the example of 2⁷-1 bits
at 10 GHz, the bit-pattern delay in the first stage of the OCM-4 is 6.4
nsec, and 3.2 nsec in the second stage.  For researchers who use
several different bit-pattern/pulse-rate combinations, kits are
available enabling the user to reconfigure the OCM.

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