We suggest vortex phase elements to detect the polarization state of the focused incident beam. We analytically and numerically show that only the types of polarization (linear, circular, or cylindrical) can be distinguished in the low numerical aperture (NA) mode. Sharp focusing is necessary to identify the polarization state in more detail (direction or sign). We consider a high NA micro-objective and a diffractive axicon as focusing systems. We show that the diffractive axicon more precisely detects the polarization state than does the micro-objective with the same NA.
We analytically and numerically show that by introducing asymmetry into axicon design it becomes possible to generate the longitudinal E-field component on the optical axis for linearly and circularly polarized incident beams. Binary axicons with high numerical aperture (NA) are fabricated in three configurations—axisymmetric and spiral, and bi-axicon—by electron beam lithography. Experimental measurements for the near-field diffraction of the most common and easy to implement incident beams—linearly and circularly polarized—are conducted. The experimental results agree with the theoretical analysis.
Исследуется пространственное распределение интенсивности остросфокусированного пучка Гаусса-Лагерра в зависимости от состояния однородной (линейной и круговой) поляризации и порядка вихревой фазы. Показано, что наибольшее влияние состояние поляризации оказывает на продольную компоненту электрического вектора светового поля. Наибольшее визуальное различие в картине общей интенсивности в зависимости от поляризации наблюдается при использовании вихревой фазы первого порядка. Использование аксикона позволяет усилить фокусировку по сравнению с апланатическим объективом. Ключевые слова: острая фокусировка, пучки Гаусса-Лагерра, оптические вихри, аксикон. Цитирование: Савельев, Д.А. Особенности острой фокусировки вихревых пучков Гаусса
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