arXiv subjects

Isha Sharma

Publications and source records attributed to Isha Sharma.

5 recordsLinked to original sources

arXiv2026

Widely tunable SNAP microresonators via translation of side-coupled optical fibers

We demonstrate free spectral range (FSR) tunable Surface Nanoscale Axial Photonics (SNAP) microresonators induced by side-coupled parallel optical fiber segments. By translating one segment relative to the other, we tune the coupling length from $900~\mu$m to $100~\mu$m and thereby tune the microresonator FSR from $5$ pm to $50$ pm, with an estimated precision of better than $0.003$ pm. The microresonator Q-factor exceeds $10^5$ and can potentially be significantly increased in a clean lab environment. Possible applications of the demonstrated device include miniature and low-loss tunable delay lines and optical frequency comb generators, as well as ultraprecise tunable optical sensors.

physics.optics↗

arXiv2025

3D Gaussian Modeling and Ray Marching of OpenVDB datasets for Scientific Visualization

3D Gaussians are currently being heavily investigated for their scene modeling and compression abilities. In 3D volumes, their use is being explored for representing dense volumes as sparsely as possible. However, most of these methods begin with a memory inefficient data format. Specially in Scientific Visualization(SciVis), where most popular formats are dense-grid data structures that store every grid cell, irrespective of its contribution. OpenVDB library and data format were introduced for representing sparse volumetric data specifically for visual effects use cases such as clouds, fire, fluids etc. It avoids storing empty cells by masking them during storage. It presents an opportunity for use in SciVis, specifically as a modeling framework for conversion to 3D Gaussian particles for further compression and for a unified modeling approach for different scientific volume types. This compression head-start is non-trivial and this paper would like to present this with a rendering algorithm based on line integration implemented in OptiX8.1 for calculating 3D Gaussians contribution along a ray for optical-depth accumulation. For comparing the rendering results of our ray marching Gaussians renderer, we also implement a SciVis style primary-ray only NanoVDB HDDA based ray marcher for OpenVDB voxel grids. Finally, this paper also explores application of this Gaussian model to formats of volumes other than regular grids, such as AMR volumes and point clouds, using internal representation of OpenVDB grid class types for data hierarchy and subdivision structure.

cs.GR↗

arXiv2025

Widely FSR tunable high Q-factor microresonators formed at the intersection of straight optical fibers

We present a new class of high-Q tunable microresonators formed at the intersection of two straight silica optical fibers, whose free spectral range (FSR) can be widely tuned by fiber rotation. The proposed configuration avoids the limitations of traditional monolithic microresonators that lack FSR tunability required for a wide range of photonic applications. Using small rotation angles (1-15 mrad), we demonstrate a tunability of the FSR from 2 pm to 10 pm, enabled by microscale fiber displacements that reshape the resonator profile over millimeter scales. The proposed approach minimizes mechanical stress, supports miniaturization, and is suitable for integration with MEMS. It paves the way for the fabrication of tunable delay lines, ultralow repetition rate broadband frequency comb generators, and nonlocal optofluidic sensors on a chip.

physics.optics↗

arXiv2025

3D Gaussian Particle Approximation of VDB Datasets: A Study for Scientific Visualization

The complexity and scale of Volumetric and Simulation datasets for Scientific Visualization(SciVis) continue to grow. And the approaches and advantages of memory-efficient data formats and storage techniques for such datasets vary. OpenVDB library and its VDB data format excels in memory efficiency through its hierarchical and dynamic tree structure, with active and inactive sub-trees for data storage. It is heavily used in current production renderers for both animation and rendering stages in VFX pipelines and photorealistic rendering of volumes and fluids. However, it still remains to be fully leveraged in SciVis where domains dealing with sparse scalar fields like porous media, time varying volumes such as tornado and weather simulation or high resolution simulation of Computational Fluid Dynamics present ample number of large challenging data sets. The goal of this paper hence is not only to explore the use of OpenVDB in SciVis but also to explore a level of detail(LOD) technique using 3D Gaussian particles approximating voxel regions. For rendering, we utilize NVIDIA OptiX library for ray marching through the Gaussians particles. Data modeling using 3D Gaussians has been very popular lately due to success in stereoscopic image to 3D scene conversion using Gaussian Splatting and Gaussian approximation and mixture models aren't entirely new in SciVis as well. Our work explores the integration with rendering software libraries like OpenVDB and OptiX to take advantage of their built-in memory compaction and hardware acceleration features, while also leveraging the performance capabilities of modern GPUs. Thus, we present a SciVis rendering approach that uses 3D Gaussians at varying LOD in a lossy scheme derived from VDB datasets, rather than focusing on photorealistic volume rendering.

cs.GR↗

arXiv2020

AMP: Authentication of Media via Provenance

Advances in graphics and machine learning have led to the general availability of easy-to-use tools for modifying and synthesizing media. The proliferation of these tools threatens to cast doubt on the veracity of all media. One approach to thwarting the flow of fake media is to detect modified or synthesized media through machine learning methods. While detection may help in the short term, we believe that it is destined to fail as the quality of fake media generation continues to improve. Soon, neither humans nor algorithms will be able to reliably distinguish fake versus real content. Thus, pipelines for assuring the source and integrity of media will be required---and increasingly relied upon. We propose AMP, a system that ensures the authentication of media via certifying provenance. AMP creates one or more publisher-signed manifests for a media instance uploaded by a content provider. These manifests are stored in a database allowing fast lookup from applications such as browsers. For reference, the manifests are also registered and signed by a permissioned ledger, implemented using the Confidential Consortium Framework (CCF). CCF employs both software and hardware techniques to ensure the integrity and transparency of all registered manifests. AMP, through its use of CCF, enables a consortium of media providers to govern the service while making all its operations auditable. The authenticity of the media can be communicated to the user via visual elements in the browser, indicating that an AMP manifest has been successfully located and verified.

cs.MM↗