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We present a simple and robust approach to reduce laser speckle, which has limited the adoption of lasers in imaging and display applications. We use colloidal solutions that can quickly reduce speckle contrast due to the Brownian motion of…

Optics · Physics 2017-03-30 Brandon Redding , Graham Allen , Eric R. Dufresne , Hui Cao

Rotating Synthetic Aperture Radar (ROSAR) can generate a 360$^\circ$ image of its surrounding environment using the collected data from a single moving track. Due to its non-linear track, the Back-Projection Algorithm (BPA) is commonly used…

Signal Processing · Electrical Eng. & Systems 2023-09-18 Wei Zhao , Cai Wen , Quan Yuan , Rong Zheng

As light propagates along a waveguide, a fraction of the field can be reflected by Rayleigh scatterers. In high-quality-factor whispering-gallery-mode microresonators, this intrinsic backscattering is primarily caused by either surface or…

We theoretically investigate a scheme in which backward coherent anti-Stokes Raman scattering (CARS) is significantly enhanced by using slow light. Specifically, we reduce the group velocity of the Stokes excitation pulse by introducing a…

Optics · Physics 2017-01-03 Li Gong , Haifeng Wang

A highly stable diode-pumped circulation-free liquid dye laser in a vertical external cavity is reported. The design is simple (no fabrication process step required, no fluid circuitry), compact (~ cm sized), and cost-effective. An optical…

Optics · Physics 2022-03-31 A. Hamja , S. Chénais , Sebastien Forget

This paper presents experimental results that allow for the performance evaluation of a straight-line reference alignment system based on pseudo-nondiffracting Layer beams. Sensors, developed specifically for this system, feature four…

Using conventional refraction-based optical lens, it is challenging to achieve both high-resolution imaging and long-working-distance condition. To increase the numerical aperture of a lens, the working distance should be compensated, and…

Optics · Physics 2018-09-12 YoonSeok Baek , KyeoReh Lee , YongKeun Park

Fourier-based optical computing operations, such as spatial differentiation, have recently been realized in compact form factors using flat optics. Experimental demonstrations, however, have been limited to coherent light requiring laser…

Optics · Physics 2021-12-07 Xiaomeng Zhang , Benfeng Bai , Hong-Bo Sun , Guofan Jin , Jason Valentine

Laser cutting of semiconductor wafers and transparent dielectrics has become a dominant process in manufacturing industries, encompassing a wide range of applications from flat display panels to microelectronic chips. Limited by the…

We observe that focusing a femtosecond laser beam simultaneously chirped in time and space domains in glass can efficiently suppress the optical aberration caused by the refractive index mismatch at the interface of air and the glass…

Optics · Physics 2018-08-15 Peng Wang , Wei Chu , Wenbo Li , Yuanxin Tan , Jia Qi , Yang Liao , Zhanshan Wang , Ya Cheng

We report a diffuse Maxwellian illumination scheme for wide-field retinal laser Doppler holography. Inserting an engineered diffuser in the illumination arm transforms a spatially concentrated near-infrared laser focus into an angularly…

We describe a two-beam interference structured illumination fluorescence microscope. The novelty of the presented system lies in its simplicity. A programmable electro-optical spatial light modulator in an intermediate image plane enables…

Coherent beam combination is one promising way to overcome the power limit of one single laser. In this paper, we use a Multi-Plane Light Converter to combine 12 fibers at 1.03 micron with a phase locking setup. The overall loss measurement…

Light source is a foundational to photonic science and technology. However, a significant challenge remains in generating and distributing coherent light from a single on-chip source with high phase stability across multiple channels.…

Optics · Physics 2026-02-05 Xiangrui Hou , Dongyi Wang , Fangyu Wang , Congwei Lu , Zhaoju Yang , Guancong Ma

Each successive generation of x-ray machines has opened up new frontiers in science, such as the first radiographs and the determination of the structure of DNA. State-of-the-art x-ray sources can now produce coherent high brightness keV…

3D surface reconstruction is essential across applications of virtual reality, robotics, and mobile scanning. However, RGB-based reconstruction often fails in low-texture, low-light, and low-albedo scenes. Handheld LiDARs, now common on…

Image and Video Processing · Electrical Eng. & Systems 2024-12-02 Nikhil Behari , Aaron Young , Siddharth Somasundaram , Tzofi Klinghoffer , Akshat Dave , Ramesh Raskar

In absence of a lens to form an image, incoherent or partially coherent light scattering off an obstructive or reflective object forms a broad intensity distribution in the far field with only feeble spatial features. We show here that…

We develop a green light source with low spatial coherence via intracavity frequency doubling of a solid-state degenerate laser. The second harmonic emission supports many more transverse modes than the fundamental emission, and exhibit…

We demonstrate speckle noise reduction in an in-line holographic imaging system using a Zwitterion-doped liquid crystal dynamic scatterer (LCDS) cell diffuser. Integrated into a minimally modified bright-field microscope, the LCDS actively…

We present the experimental realization of a laser system for ground to satellite optical Doppler ranging at the atmospheric turbulence limit. Such a system needs to display good frequency stability (a few parts in 10^{-14}) whilst allowing…

Optics · Physics 2013-11-12 Nicola Chiodo , Khelifa Djerroud , Ouali Acef , Andre Clairon , Peter Wolf