Although optical-spectrum analysis and polarization measurement methods are not generally related, a collaborative effort by scientists at Tianjin University (Tianjin, China), General Photonics (Chino, CA), and the University of Southern California (Los Angeles, CA) has resulted in a polarimeter-based optical-spectrum analyzer (P-OSA) that measures with a speed and resolution that cannot be achieved using traditional grating-based, filter-based, or interferometric methods. In fact, the method works so well that it has been used to successfully measure the instantaneous wavelength, direction of wavelength change, and even the spectral shape of both step-tuned and swept-wavelength sources--data that cannot be obtained by conventional spectral measurement techniques. Conventional OSA measurement techniques prevent simultaneous achievement of high resolution, wide spectral range, and fast measurement speed. For example, measurement range and spectral resolution are inversely proportional in Fabry-Perot filter-based OSAs; one must be sacrificed for the other. And while diffraction-grating-based OSAs with a charge-coupled-device (CCD) sensor can be fast, resolution and scanning range are limited by the size of the CCD and high diffraction orders from the grating if the spectral range is too large or the grating period is too small.
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