Research Projects

The proposed project aims to design, develop, and demonstrate inhomogeneous waveplates based on the principle of conjugate optics, specifically utilizing the Alvarez– Lohmann (AL) approach. Traditional waveplates are homogeneous in nature and offer fixed phase retardance and fast axis orientation; however, advanced optical applications in structured light generation, singular optics, beam shaping, and adaptive photonics increasingly demand waveplates with spatially varying phase retardance and fast axis orientation distribution, also called inhomogeneous waveplates. These components are critical for tailoring complex light fields, including optical vortices and vector beams, for cutting-edge applications in optical communication, microscopy, and quantum optics. The concept of conjugate optics, as employed here, involves two freeform optical elements with cubic surface profiles arranged along the optical axis. By introducing a lateral shift, the total device thickness varies within the effective aperture region. This variation in effective thickness leads to a corresponding change in the phase distribution across the aperture. By extending this concept with birefringent materials, this lateral shifting enables precise control over the local birefringence properties, effectively allowing the engineering of inhomogeneous retardance and fast axis orientation patterns. Such a mechanism offers a reconfigurable, passive, and highly tunable platform for generating spatially variant polarization states and phase distributions. This project will address both the theoretical design and experimental realization of these wave- plates. Theoretical modeling will be carried out to determine the required surface profiles and displacement parameters for achieving desired phase distributions (e.g., for generating cylindrical vector beams, radial polarization states, or tunable vortex beams). The fabrication of the designed elements will employ modern techniques such as electron beam lithography or direct laser writing, ensuring the required precision for sub-wavelength optical structures. The key novelty of this work lies in exploiting the AL configuration to create inhomogeneous optical retarders that are mechanically tunable, flexible in design, and scalable for a wide range of wavelengths and applications. We noticed that these ideas are not tried by anyone in the optics community. The outcome of this project is expected to lead to compact and versatile optical devices suitable for use in next-generation optical systems, including adaptive optics, optical trapping, and photonic computing.