Gian-Thompson polarizer

The excitation of the t-PL was carried out using a continuous wave NdrYLF laser with a wavelength of 266 nm (hio = 4.66 eV), i.e. a photon energy between the GaN (3.5 eV) and AIN (6.2 eV) band gaps. The laser spot was about 1.5 am in diameter. The density of QDs in our samples is about lO" cm, so about 10 QDs was excited in the experiment. Polarization of radiation from the sample was rotated by a half-wave plate and was analyzed by Gian Thompson polarizer. The p-PL signal was detected by a liquid-nitrogen cooled UV-enhanced CCD camera. 

Figure 1 OHD-RIKES experimental setup. DX = Doubling crystal GLP = Gian laser polarizer GTP = Glan-Thompson polarizer HWP = half-wave plate PD = photodiode PDC = prism dispersion compensator QWP = quarter-wave plate SF = spatial filter. (From Ref. 34.)...

Polarized radiation may be produced rather more easily than at longer wavelengths, by the use of a Gian Thompson prism or, over part of the range, by Polaroid. 

The set-up is similar to the one used in normal saturation spectroscopy but the probe beam is now blocked by crossed polarizers that are placed at opposite sides of the absorption ceU. The polarizer in front of the cell is used to increase the linear polarization of the laser beam, which is frequently already well polarized. A matched pair of polarizers (frequently Gian-Thompson prisms. Fig. 6.46) can have a rejection ratio of 10 to 10 in the crossed position. The pump beam is circularly polarized and induces an anisotropy... 

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