3D coherent single shot lidar imaging beyond coherence length.

Advancements in remote sensing and autonomous vehicle technologies made lidars equally important for unmanned objects alongside cameras. Therefore, precise 3D lidar imaging and point cloud generation have become important subjects. Although existing coherent lidar technologies provide precise imaging results, the spectral linewidth of the laser sources becomes a key limitation over long distances as it defines the maximum detection range.

Ranging and velocimetry measurements by phase-based MTCW lidar.

We propose a complementary phase detection algorithm to enhance the capabilities of the multi-tone continuous wave (MTCW) lidar for single-shot simultaneous ranging and velocimetry measurements. We show that the phase of the Doppler-shifted RF tones and the amount of the induced Doppler frequency shift can be used to extract the phase and velocity information, simultaneously. A numerical case study and experimental work have been performed for the proof of concept.

Simultaneous ranging and velocimetry with multi-tone continuous wave lidar.

In this paper, we demonstrate analytical modeling and experimental verification of simultaneous ranging and velocimetry measurements in multi-tone continuous wave lidars. To assess the ranging performance of the proposed lidar, a comparative experiment of the multi-tone continuous wave and time-of-flight techniques is performed. The average deviation in ranging is ∼0.

Laser-Inscribed Diamond Waveguide Resonantly Coupled to Diamond Microsphere.

An all-diamond photonic circuit was implemented by integrating a diamond microsphere with a femtosecond-laser-written bulk diamond waveguide. The near surface waveguide was fabricated by exploiting the Type II fabrication method to achieve stress-induced waveguiding. Transverse electrically and transverse magnetically polarized light from a tunable laser operating in the near-infrared region was injected into the diamond waveguide, which when coupled to the diamond microsphere showed whispering-gallery modes with a spacing of 0.

Silicon microsphere whispering gallery modes excited by femtosecond-laser-inscribed glass waveguides.

We report on the coupling of whispering gallery modes in a 500-μm-radius silicon microsphere to a femtosecond-laser-inscribed glass optical waveguide. The shallow glass waveguide with a large mode field diameter in the near-infrared is written at a depth of 25 μm below the glass surface, resulting in a high excitation impact parameter of 525 μm for the microsphere. The excited whispering gallery modes of the silicon microsphere have quality factors of approximately 10 in the 90° elastic scattering and 0° transmission.

Spatial intensity profiling of elastic and inelastic scattering in isotropic and anisotropic liquids by immersion of a spherical silicon photocell.

The transverse spatial intensity distribution of elastic and inelastic light scattering in passive and active as well as weak and strong scattering liquid media has been studied by using Sphelar One p-n junction silicon spherical photocells. We immersed a Sphelar One in these scattering solutions and measured the photoconductive response in reverse biased photodiode (PD) configuration. The passive weak scattering medium was pure ethanol (EtOH), whereas the passive strong scattering medium was 5CB nematic liquid crystal (NLC).