THORLABS INT-POL-1300, Operation Manual

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3 Detailed Description
INT-POL-1300 / page 9
0 15 30 45 60 75
-60
-50
-40
-30
-20
-10
0
10
A
m
plitude (dB
)
Frequency (MHz)
Figure 4: INT-POL-1300 RF OUTPUT frequency response
The balanced detector RF-OUTPUT includes an active filter section to suppress the
generation of aliasing frequencies in the digitized fringe signal, which would degrade
the quality of the OCT image. The active filter is designed for a sample rate of
50 Msample/sec. Signal frequencies beyond 25 MHz are suppressed by more than
20 dB. For different sample rates, the filter design can be modified accordingly -
please contact Thorlabs GmbH for details.
The signal monitor outputs ( and MONITOR-) allow observation of the
power levels on each detector and can be used as independent power meters for
each channel. The conversion gain of the monitor outputs is 5V/mW. The maximum
output voltage swing of the MONITOR output is +10 V for high impedance loads
(+1.5 V into 50

). Saturation of MONITOR outputs will occur at optical power level
greater than 2 mW, reaching the detector. The power level on each detector depends
on PBS splitting ratio, i.e. input polarization.
To achieve same power levels polariza-
tion controllers previous the optical inputs are needed.
The 3 dB bandwidth of the MONITOR signal is DC-5 MHz. Figure 4 shows a typical
frequency response curve of INT-POL-1300 MONITOR signal. For this measurement
a test signal was applied to one input port only. MONITOR outputs can be used to
measure RF modulated signals on each detector separately.