This study presents a phase-modulation technique capable of flexibly extending the depth-of-field (DOF) of any diffraction pattern. This method, deep diffractive optics (DDO), involves integrating a needle-shaped beam phase modulator with a conventional phase pattern design. Our findings reveal that these current DDOs can significantly extend the DOF over traditional diffractive optics by a factor of five. This method holds broad potential for applications in various optical devices, systems, and emerging fields of photonics.

A three-wavelength-converted light source based on patterned quantum dot film fabricated by a photolithographic process and blue led was proposed to on-axis multi-wavelength digital holography. A patterned quantum dot film was fabricated based on a photolithographic process. Each process was executed based on quantum dot particles-SU8 photoresist mixture. To improve the conversion efficiency of a quantum dot film, TiO2 film was also patterned among quantum dot films as a role of scattering barrier. From the experiment result, a stepped object with 1.8µm height was reconstructed, and amplified noise could be suppressed from 88nm to 19nm.

The Bragg selectivity of holograms recorded in polymers often fits poorly to theory derived for perfectly rigid hosts. We present closed-form and numerical solutions of the coupled-mode equations for distorted holograms in soft hosts. Fits extract index contrast, thickness and distortion from Bragg selectivity that strongly deviates from existing theory.

Rotated chirped volume Bragg gratings(r-CVBGs) have recently emerged as a unique optical element with use in a diverse and wide range of applications including compact spectrometers, pulse phase modulation, and others. They are offering noteworthy advantages over conventional surface gratings including compactness, robustness, and high-power handling capabilities. The recording of r-CVBGs in photo-thermo-refractive-glass (PTR) utilizing holographic techniques brings flexibility to the design of the grating while requiring careful and precise recording system alignment. The comprehensive design and fabrication process of r-CVBGs provides insights for the future development of these promising optical components.

Fresnel zone aperture (FZA) lensless imaging encode the incident light into hologram-like pattern, so that the scene image can be refocused by back propagation method. However, the inherent twin image and inaccuracy focusing distance degrade the imaging quality. This brings difficulties for the target classification and recognition applications. We proposed a high-quality reconstruction and autofocusing method for FZA lensless imaging. By investigating the image sharpness metrics on the back propagation images, the accuracy focusing distance could be estimated. Total variation regularization based alternating direction method of multipliers algorithm is proposed to suppress the twin image existing in the back propagation reconstruction. Experimental results show that the proposed method can significantly improve the target recognition rate from 4.06% to 90.00%.

Wide field of view (FOV) free space optical communication systems (FSOCs) have gained attention due to their potential for enhanced data transmission and expanded coverage. These systems can use volume holographic optical elements (HOEs) for their narrow filtering. However, HOE filtering characteristics depend on the substrate thickness, limiting the FOV for thicker substrates. Multiplexing can enhance the FOV but reduces the refractive index modulation. To overcome these limitations, we propose a novel method that involves writing plane wave beams to a hollow cylindrical substrate, thus doubling the FOV. Experimental and theoretical results support this approach, offering the potential for 360° panoramic FSOCs.

The Bragg selectivity of a volume hologram is a crucial characterization metric, but distorted Bragg selectivity curves obtained from holograms in soft media cannot be evaluated by existing analysis techniques. We demonstrate that distorted Bragg curves arise from mechanical strain within the polymer network, causing non-uniform distortion of the grating fringe spacing. We then present a method for obtaining spatially resolved Bragg selectivity curves and for evaluating the local and global hologram fidelity.

This study demonstrates a coherent frequency modulated continuous wave (FMCW) scanning lidar system coupled with range-selective coherent FMCW digital holography (DH), yielding broad field-of-view point cloud images and high-resolution holographic images of objects at selected ranges. The integration of DH into a Cassegrain telescope enables long-range phase-sensitive imaging, improving upon traditional DH systems. A chirped frequency modulation technique is used to capture holograms at specified ranges, with a current range resolution of 7 cm. The research details the technicalities, challenges, and future directions of this approach, which marks a substantial advancement in coherent 3D imaging and sensing technologies.