Coherence and polarization optics

Electromagnetic coherence

Partial coherence and partial polarization are fundamental characteristics of light fields. Interest in them has significantly increased in recent years as the progress in optical sciences has led to the utilization of photonic components that operate in regimes necessitating full electromagnetic (vector) description. Examples of such components include optical microcavities, photonic crystal elements, and plasmonic structures involving evanescent near fields.

Researchers at UEF contribute to the development of theoretical foundation for treating polarization and electromagnetic coherence in both beam fields and general non-paraxial wave fields, including the near-field situations. The research covers both theoretical and experimental work. Recently, we have directed our research also towards quantum-field formulation of electromagnetic coherence and to the development of ghost polarimetry with classical light.

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RECENT PUBLICATIONS:

[1] A. Shevchenko, M. Roussey, A. T. Friberg, and T. Setälä, “Polarization time of unpolarized light”, Optica 4, 64 (2017).

[2] A. T. Friberg and T. Setälä, “Electromagnetic theory of optical coherence”, J. Opt. Soc. Am A 33, 2431 (2016). (Invited)

[3] A. Hannonen, A. T. Friberg, and T. Setälä, “Classical spectral ghost ellipsometry”, Opt. Lett. 41, 4943 (2016).

[4] K. Blomstedt, T. Setälä, J. Tervo, B. J. Hoenders, J. Turunen, and A. T. Friberg, “Vector-valued Lambertian fields and their sources”, Phys. Rev. A 93, 053813 (2016).

[5] A. Norrman, T. Setälä, and A. T. Friberg, “Generation and electromagnetic coherence of unpolarized three-component light fields”, Opt. Lett. 40, 5216 (2015).

[6] L.-P. Leppänen, K. Saastamoinen, A. T. Friberg, and T. Setälä, “Interferometric interpretation for the degree of polarization of optical beams”, New J. Phys. 16, 113059 (2014).

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Optical coherence in near fields

Optical evanescent near fields are examples of genuine three-component electromagnetic fields whose coherence and polarization properties cannot always be investigated with the traditional beam-field techniques. In order to access their coherence properties novel near-field nanoprobing methods must be developed. In addition, extra richness to near-field electromagnetic coherence is brought by the possible resonant surface-wave excitations such as surface plasmon polaritons whose presence may significantly alter the statistical properties of near fields.

At UEF we are developing the one-probe and two-probe polarization and coherence detection methods for the quantification of optical beams and near fields. The work benefits from the nanofabrication facilities of UEF where various nano-particle probes can be fabricated. We also focus on the effect of surface plasmon polaritons and the analysis of their coherence properties.

CONTACT PERSONS:

RECENT PUBLICATIONS:

[1] A. Norrman, S. A. Ponomarenko, and A. T. Friberg, "Partially coherent surface plasmon polaritons", EPL, in press.

[2] L.-P. Leppänen, K. Saastamoinen, J. Lehtolahti, A. T. Friberg, and T. Setälä, ‘’Detection of partial polarization of light beams with dipolar nanocubes’’, Opt. Express 24, 1472 (2016).

[3] L.-P. Leppänen, K. Saastamoinen, A. T. Friberg, and T. Setälä, “Detection of electromagnetic degree of coherence with nanoscatterers: comparison with Young's interferometer”, Opt. Lett. 40, 2898 (2015).

[4] A. Norrman, T. Setälä, and A. T. Friberg, “Partial coherence and polarization of a two-mode surface-plasmon polariton field at a metallic nanoslab”, Opt. Express 23, 20696 (2015).

[5] A. Norrman, T. Setälä, and A. T. Friberg, “Long-range higher-order surface-plasmon polaritons”, Phys. Rev. A 90, 053849 (2014).

[6] L.-P. Leppänen, A. T. Friberg, and T. Setälä, “Partial polarization of optical beams and near fields probed with a nanoscatterer”, J. Opt. Soc. Am. A 31, 1627 (2014).

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Optical coherence of non-stationary fields

Optical coherence of non-stationary fields

Individual pulses in pulse trains from, e.g., mode-locked lasers or supercontinuum sources are typically not identical and thus the train can be considered as a partially spectrally and temporally coherent ensemble of realizations.

The aim is to model the correlation properties of such pulse trains using the coherence theory of non-stationary fields, numerical simulations of supercontinuum generation, and experimental measurements with techniques such as frequency-resolved optical gating. The models for spectral and temporal coherence then allow one to simulate the results of interferometric and other experiments with pulse trains, and to optimize the experimental setups.

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Keywords: coherence; polarization; near fields; non-stationary fields