8
4. Free space alignment
Back-to-back in a single MUX/DEMUX configuration
The first step is to align a single multiplexer in a back-to-
back measurement. The light coming from the multiplexer will
be sent to a mirror and back to the system being used in the
demultiplexer configuration.
Minimum material:
•
Light source at the required wavelength
•
Light circulator
•
PowerMeter
•
Mirror
•
Lens
•
Infrared detector card
Recommended material:
•
Optical switch
•
Multichannel power meter
•
Circulator on each channel
Sending the light back to the system will enable the
measurement of insertion losses and the basic functionality of
the multiplexer.
Depending on the material available, possible options are Figure
1 with only 1 lens, or Figure 2 with two lenses. We recommend
option 2 with two lenses as it gives more flexibility and precision.
It also makes it easier to view the light with an infrared card.
MPLC
L1
M1
Mirror to reflect the light
Colimated beam at the
output of the multiplexer
Lens to focus the light on
the mirror
Figure 1: Illustration of a single MPLC measurement using a single lens.
MPLC
L1
M1
Mirror to reflect the light
300
µ
m radius waist colimated beam
at the output of the multiplexer
Two lenses used as a telescope to adapt
the beam size.
L2
Figure 2: Illustration of a single MPLC measurement using two lenses.
