Associated With Spatial Filtering Of The Thermo-optical Subwavelength Interference

Correlated imaging and correlated interference were first realized with quantum entangled system. However, the recent studies showed that the thermal light sources can also realize correlated imaging and correlated interference, and thus brake the limitation of quantum entangled source. The inquiry that correlated imaging concerns quantum entanglement or classical correlation was evoked. From that on, correlated interference and correlated imaging became a hot topic. We propose the idea of correlated filtering in the correlated interference experiment in this thesis. Correlated filtering can increase the visibility degree of the correlated interference fringes. We design an incoherent two-photon interferometer to obtain sub-wavelength interference fringes by two-photon intensity measurement.Visibility is one of the important quality parameter for optical imaging. If the visibility of the correlated images in the experiment becomes larger, the correlated images become clearer, and more details of the objects can be reflected, we finally can find more information of the objects. We theoretically analyze an important factor, the correlated area of the light beam, in correlated imaging and correlated interference experiment. We find that the field intensity is proportional to the correlated area of the light beam. Following with the theoretical analysis and correlated filtering, we insert an optical diagraph into the empty arm, in accordance with the symmetrical position of the object. By diminishing the size of the optical diagraph, we can obtain the correlated interference fringes with good visibility.Sub-wavelength interference experiment with entangled two-photons verified quantu-m lithography, which can surpass the classical diffraction limit. The sub-wavelength interference with thermal light, which occurs at symmetrical positions, can not be used in quantum lithography. In the thesis we design an incoherent interferometer to obtain the sub-wavelength interference fringes by two-photon intensity measurement at the same position. In the interferometer, the field wave front in the input plane is inverted in one arm to the output plane. We also find in the sub-wavelength interference experiment that the sub-wavelength interference fringes are independent of the alignment and super-position of the two correlated beams. If the centers of the two beams are not overlapped, we can still obtain the sub-wavelength interference fringes. The center of the fringes is positioned at the center of the two beams. Therefore, our experiment design can fit for rough conditions.