• Korean Journal of Optics and Photonics
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• v.33 no.2
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• pp.59-66
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• 2022

A free-form Mueller matrix ellipsometer (MME) based on independent control of the azimuthal angle of each polarizing element is introduced. The azimuthal angles of the polarizer and the matching compensator which generate the optimum Stokes vectors of an incident beam are investigated for the polarization state generator, where the spectral responses of the retardation angle and transmittance ratio of a nonideal compensator are taken into account. Similarly, the azimuthal angles of the analyzer and the corresponding compensator are investigated for the polarization-state detector, to unambiguously determine the Stokes vector of the outcoming beam from the sample, and explicit expressions for the Stokes elements are derived. Since the suggested technique enables one to utilize a nonideal quarter-wave plate as the compensator for an MME, it will contribute to the construction and application of a Mueller matrix spectroscopic ellipsometer (MMSE) operating over a wide spectral range from deep ultra-violet to near infrared.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.1-7
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• 2004

The development of direct receiver techniques is expected to be a solution for future wideband or multi-band wireless systems based on software defined radio. In this Paper, we study the regeneration of I and Q signals for the SDR based direct conversion receiver, so that we can handle a wide bandwidth and maintain maximal flexibility in system utilization. After modeling the basic system considering the real wireless communication environment, and studying the impact of imperfect phase imbalance on the performance of a direct conversion receiver, we propose a suboptimal I and Q signal regeneration algorithm for the system. The proposed algerian regenerates I and Q signals using a real time early-late compensator which effectively estimates phase imbalances and gives feedback in a directreceiver. The proposed algorithm is shown to mitigate the impact of AWGN and improves performance especially at low SNR channel condition. According to the computer simulation, the BER performance of the proposed system is at least about 4 dB better than conventional systems under $45{\~}55$ degrees random phase errors.