Sketch, principle, and specification of the spectroscopic MO system. (a) White light from tungsten halogen lamp is fiber-coupled and collimated through the lens L1 (f = 100 mm, NA = 0.055), focused on the sample through L2 and re-collimated by L3 (L2, L3: f = 10 mm, NA = 0.40), and detected by the spectrometer through a collimation lens (L4) coupled to the fiber. The light intensity is adjusted by the neutral density filter (ND). z-axis is in the horizontal plane and parallel to the light propagation direction. Sample (S) mounted on a xy plane-motorized stage is placed between the polarizer (P, φ) and analyzer (A, −45°). Magnetic field is applied along z-axis and CCD is used for imaging and checking focus condition of L2. QW denotes achromatic quarter-wave plate and is inserted when measuring Faraday ellipticity. (b) Spectrum of light intensity measured by the spectrometer. (c) Standard deviation of light intensity by 800 repeated measurements. (d)–(f) Experimental distribution of light intensity at three typical wavelengths. Solid lines are the Gaussian distribution of Eq. (5). (g) Standard deviation of angle is inversely proportional to the light intensity (I) and proportional to its standard deviation (σ I ) as shown in the inset (I = 60 000 counts).
(a) Light intensity spectra after passing through the glass sheet and (b) its standard deviation. (c) Standard deviation of θ F over 800 measurements. (d) Statics of θ F at 650 nm over 800 measurements and fitting to Gaussian distribution.
(a) Faraday rotation and ellipticity spectra of Au/[Pt/Co]n/Au thin film measured by this setup with polarizer at 0°, blue diamond is the Faraday rotation measured by using a LD at 656.8 nm with a differential detector. (b) MO loop extracted from the spectroscopic data at 656.8 nm, and (c) that by differential detector with a LD at 656.8 nm.
Transmittance and magnetic field induced Faraday rotation of bulk GaAs (0.625 mm thick). Inset shows the enlarged view near band edge.
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