BCB-
4 User’s Manual
Page 8 of 14
Optilab, LLC
600 E. Camelback Road, Phoenix, AZ 85012
Phone: (602) 343-1496, Fax: (602) 343-1489, Email: [email protected]
3. Troubleshooting
S
YMPTOM
P
OSSIBLE
C
AUSE AND
S
OLUTION
U
NIT NOT BIASING
CORRECTLY
C:
Improper bias pin connection setting.
S:
Check to ensure that the cable between the BCB-4 and the
intended optical modulator is made correctly.
C:
Optical input to the modulator is too high/low.
S:
Due to the photodiode feedback design, the ability to bias the
modulator depends on the amount of photodiode current
feedback to the BCB-4. If the feedback power is greater than -10
dBm, it may saturate the BCB-4 photodiode current
measurement. If it is lower than -20 dBm, then the feedback
strength may be insufficient.
C:
Onboard photodiode input is too high/low.
S:
Ensure that the optical input level through the tap port is
between -20 dBm and -10 dBm for optimum performance.
C:
Improper polarization input to modulator.
S:
Check the input polarization type and axis alignment of your
modulator and confirm the input seed source is matching. An
improper optical input axis alignment will render the BCB biasing
(especially minimum mode) insufficient.
C:
No feedback loop and/or Vpi value is set incorrectly.
S:
If using a feedback loop, the Vpi programmed DAC value must
be set to 00000. If not using a feedback loop, the Vpi DAC value
should be calculated and programmed to the unit. Refer to
Appendix B of this manual for calculating and/or setting the Vpi
DAC value.
U
NIT DOES NOT POWER
UP
.
C:
Improper power connection.
S:
Please ensure that 6-pin power/com and 4 pin Molex cables
are connected properly and not damaged. Please refer to
Appendix A at the end of this manual for proper wiring if the 4-pin
Molex connector.
I
NCORRECT BIAS POINT
SETTING
C:
Improper software bias point setting
S:
Connect to the BCB-4 via the RS232 setting, and check the
current bias point setting, and make adjustment accordingly.