| 1. |
- Burvall, Anna, et al.
(författare)
-
Simple lens axicon
- 2004
-
Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 43:25, s. 4838-4844
-
Tidskriftsartikel (refereegranskat)abstract
- We present the design of a cemented doublet-lens axicon made from spherical surfaces only. Compared with diffractive axicons, refractive cone axicons, and earlier lens axicons with aspheric surfaces, this element is inexpensive and easy to manufacture even with large apertures. The lens axicon is based on the deliberate use of the spherical aberration of the surfaces. The design principles of the element and its characterization, numerically and experimentally, are presented in detail. Although performance was traded for simplicity and robustness, the results show that the lens axicon has the main axicon properties: a narrow, extended line focus of relatively constant width.
|
|
| 2. |
|
|
| 3. |
- Lindberg, J., et al.
(författare)
-
Spectral analysis of resonant transmission of light through a single sub-wavelength slit
- 2004
-
Ingår i: Optics Express. - 1094-4087. ; 12:4, s. 623-632
-
Tidskriftsartikel (refereegranskat)abstract
- We analyze the spectral properties of resonant transmission of light through a sub-wavelength slit in a metal film. We show that the enhanced transmission can be understood in terms of interfering surface-wave-like modes propagating in the slit. We characterize the effect of geometrical and material properties of the slit on the transmission spectrum. Furthermore, we show that the wavelength of the transmission resonance strongly depends on the surrounding medium. This effect may be utilized in sensors, imaging, and the detection of, e.g. biomolecules.
|
|
| 4. |
- Setala, T., et al.
(författare)
-
Intensity fluctuations and degree of polarization in three-dimensional thermal light fields
- 2004
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 29:22, s. 2587-2589
-
Tidskriftsartikel (refereegranskat)abstract
- The normalized intensity fluctuations of arbitrary electromagnetic wave fields obeying Gaussian statistics are expressed in terms of the three-dimensional degree of polarization. This general formulation implies an important physical result concerning the polarization of planar fields and the dimensionality of the formalism. The results are expected to be particularly useful in intensity interferometry.
|
|
| 5. |
- Setala, T., et al.
(författare)
-
Universality of electromagnetic-field correlations within homogeneous and isotropic sources
- 2003
-
Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 67:2
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the structure of second-order correlations in electromagnetic fields produced by statistically stationary, homogeneous, and isotropic current distributions. We show that the coherence properties of such fields within a low-loss or nondissipative medium do not depend on the source characteristics, but are solely determined by the propagation properties, and that the degree of coherence of the field is given by the sinc law. Our analysis reproduces the known results for blackbody fields, but it applies to a wider class of sources, not necessarily in thermal equilibrium. We discuss the physics behind the universal behavior of the correlations by comparing the results with those obtained by an electromagnetic plane-wave model.
|
|
| 6. |
- Setälä, T., et al.
(författare)
-
Intensity fluctuations and the degree of polarization in Gaussian random electromagnetic fields
- 2004
-
Ingår i: Riao/Optilas 2004: 5th Iberoamerican Meeting On Optics And 8th Latin American Meeting On Optics, Lasers, And Their Applications, Pts 1-3: Ico Regional Meeting. - : SPIE. - 081945575X ; , s. 1124-1128
-
Konferensbidrag (refereegranskat)abstract
- For an electromagnetic beam described by Gaussian statistics the normalized intensity fluctuations are known to depend on the beam's degree of polarization. With general non-paraxial random electromagnetic waves, such as optical near fields, a complete characterization of the polarization state requires a 3 x 3 coherence matrix and a three-dimensional degree of polarization. We demonstrate that, under the assumption of Gaussian statistics, the normalized intensity fluctuations in the three-dimensional case are expressible in terms of the three-dimensional degree of polarization. Since such a general description can be employed even for beams with only a transverse electric field, several important physical results follow from comparison of the three-dimensional and usual two-dimensional formulations. The results are expected to be particularly important in intensity interferometry.
|
|
