An optical intensity control system for use with an optical switch
providing individual signal paths between input and output ports. The
system has a optical splitters connectable to output multiplexers of the
switch and also has variable optical intensity controllers (VOICs) for
insertion into the individual signal paths. The VOICs individually
control the intensity of optical signals present in the signal paths in
accordance with intensity control signals. An equalizer is connected to
the splitters and to the VOICS, for producing an estimate of the optical
power of each individual switched optical signal and generating the
intensity control signals. The equalizer is adapted to controllably
isolate individual switched optical signals. In this way, individual and
independent control of the power on each optical channel is provided,
wavelength-dependent losses introduced by all the devices in the switch
including the WDM devices at the output of the switch are accounted for
and one optical coupler is required for each output optical fiber. Coarse
equalization may be provided for each multiplexed optical signal either
at the switch input or output, permitting a reduction in the dynamic
range over which the VOICs inside the switch are required to operate.