Polarization selection optics

Levenson, M. D., and Eesley, G. L. 1979. Polarization selective optical heterodyne detection for dramatically improved sensitivity in laser spectroscopy. Appl. Phys. 19 1-17. Librizzi, R, Viapianni, C., Abbruzzetti, S., and Cordone, L. 2002. Residual water modulates the dynamics of the protein and of the external matrix in trehalose-coated MbCO An infrared and flash-photolysis study. J. Chem. Phys. 116 1193-1200. 

For optimum performance, CD measurements require a polarization modulated source. In principle, any of the polarization-selective optical devices discussed earlier could be mechanically moved to create the required modulation. However, this approach is problematic in that it is difficult to implement physically, the mechanical movement may introduce noise into the measurement situation, and there are limitations to the rate at which the polarization can be modulated. A preferable approach is to use an electronic device to effect the required phase retardation. Although a number of devices have been used for this purpose (e.g. magneto-optical, Kerr effect, etc.), modern CD instruments rely upon either the Pockels effect, or photoelastic modulation for this function. 

M.D. Levenson, G.L. Eesley, Polarization selective optical heterodyne detection for dramatically improved sensitivity in laser spectroscopy. Appl. Phys. 19, 1 (1979)... 

All lasers have the following three fundamental components (see Figure 1). The gain medium, the business end of the laser, is the medium in which excited states are created which will produce stimulated emission. The exciter is the source of energy for production of the excited states in the gain medium. Finally, the optical resonator determines the directionality, wavelength selectivity, optical feedback, polarization, and other characteristics of the stimulated emission from the gain medium. 

Films of pure CNLCs have a unique transmission behavior as CP light with the same sense of circular polarization as the CNLC is filtered out by reflection, while CP light of the opposite handedness as the CNLC film is transmitted. This selective optical transmission characteristic is referred to as a one-dimensional photonic stop-band or a selective reflection band. The stop-band is centered at a certain wavelength Ac, which is dependent on the pitch length p and the average refractive index n of the CNLC ... 

As discussed earlier, the PEM is, in many ways, an ideal modulation device for polarization-selective measurements. Thus, the optimum simultaneous multiwavelength CD instrument should incorporate both the PEM and CCD, and at the same time allow the PEM to operate at its resonant frequency. One way to overcome the basic incompatibility of the PEM and CCD is to use an optical demodulation scheme in which the two oppositely polarized components would be directed by a polarizing beamsplitter, to either different areas of the same CCD, or to different CCDs [14]. Since two distinct detector areas would be accessed by the oppositely polarized light, pixel-to-pixel sensitivity variations may be a significant source of noise. 

Xripathy, S. K., Viswanathan, N. K., Balasubramanian, S., and Kumar, J. Holographic fabrication of polarization selective diffractive optical elements on azopolymer film. Polym. Adv. Technol. 2000,11, pp. 1-5. 

The method takes advantage of an excite and probe technique with polarization selective detection. A circularly polarized pxnnp pulse of ps duration generates a coherent superposition of atomic substates. The coherence induces an optical anisotropy in the atomic sample, which oscillates exactly with the splitting frequency of the respective substates. 

Polarization-Selective Substrate-Mode Volume Holograms and Its Application to Optical Circulators... 

Huang, Y. (1994). Polarizing-selective volume holograms general design. Applied Optics, Vol. 33, pp. 2115-2120... 

Polarization-Selective Substrate-Mode Volume Holograms and Its Application to Optical Circulators introduces polarization-selective substrate-mode volume holograms which are applied in several novel designs of optical circulator. The described optical circulators have a number of advantages such as polarization-independence, compactness, high isolation, low polarization mode dispersion, easy fabrication, and low cost. In addition, the port number of the proposed multi-port device can be expanded easily. 

Although optical vibrational techniques are less sensitive than electron-based spectro-metric methods, these techniques are employed extensively for thin-film characterization because of the specific and characteristic vibrational spectrum shown by various functional groups and molecules present in the film. The most commonly used vibrational spectroscopic techniques are infrared (IR) and Raman spectroscopy. Because of the interference caused by absorption of IR by the underlying substrate, IR reflection-adsorption spectroscopy (IRRAS) and its polarization modulation (PM) analog, PM-IRRAS, which uses the polarization selectivity of surface adsorption, are typically employed to characterize thin films (Gregoriou and Rodman, 2006). 

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