An optical spectrum analyzer for analyzing at least n wavelengths of light is
disclosed having a tunable filter with an input port and an output port and a periodic
output response with a free spectral range FSR and having a bandwidth
B. An AWG is optically coupled to receive light from the output port; and for distributing
the light spatially at other locations in a wavelength dependent manner. Optically
coupled with the AWG are m detectors for detecting wavelength or channel information.
The number of detectors, m is less than n when a single detector is associated
with a single channel; and m is less than 2n when two detectors are associated
with a single channel.
