Patent ID: 7180599

Claim:
An apparatus comprising: a polarization controller that receives light having a wavelength as a function of time, and selectively sets a state of polarization of said received light, and provides a polarized output having a first state of polarization or a second state of polarization; a first determination unit that (a) receives said polarized output, and (b) determines a first reference wavelength as a function of time for said first state of polarization, and a second reference wavelength as a function of time for said second state of polarization; a second determination unit that (a) receives, from a device under test (DUT), a signal as a function of time, wherein said DUT generates said signal in response to said light, and (b) determines, from said signal, a property of said DUT as a function of time; and a processing unit that processes (i) said first reference wavelength as a function of time, (ii) said second reference wavelength as a function of time, and (iii) said property of said DUT as a function of time, and determines a property of said DUT as a function of wavelength.